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Effects of Geometric configuration in relativistic isobaric collisions at $\sqrt{s_{NN}}=200$ GeV
Authors:
Akash Das,
Satya Ranjan Nayak,
B. K. Singh
Abstract:
In this work, we present a study on the effects of nuclear deformation ($β_2$,$β_3$) and surface diffuseness ($a$) on the charged hadron multiplicity ($N_{\mathrm{ch}}$) and elliptic flow ($v_2$), obtained in symmetric isobaric collisions of ${}^{96}_{44}\mathrm{Ru} + {}^{96}_{44}\mathrm{Ru}$ and ${}^{96}_{40}\mathrm{Zr} + {}^{96}_{40}\mathrm{Zr}$. The two extreme configurations (tip-tip and body-…
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In this work, we present a study on the effects of nuclear deformation ($β_2$,$β_3$) and surface diffuseness ($a$) on the charged hadron multiplicity ($N_{\mathrm{ch}}$) and elliptic flow ($v_2$), obtained in symmetric isobaric collisions of ${}^{96}_{44}\mathrm{Ru} + {}^{96}_{44}\mathrm{Ru}$ and ${}^{96}_{40}\mathrm{Zr} + {}^{96}_{40}\mathrm{Zr}$. The two extreme configurations (tip-tip and body-body) were used to determine the correlation between the final state observables and initial geometry using the HYDJET++ model. The octupole deformation parameter ($β_3$) enhances $N_{\mathrm{ch}}$ in central tip-tip Zr+Zr collisions and suppresses it in peripheral ones. In mid-central to peripheral body-body Zr+Zr collisions, $β_3$ leads to a reduction in charged hadron production. Surface-diffuseness ($a$), along with quadrapole deformation ($β_2$), also shows a significant impact on multiplicity and elliptic flow. The octupole deformation enhances elliptic flow in Zr's body-body collisions. Results are compared with the STAR blind-analysis data where available.
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Submitted 24 August, 2025;
originally announced August 2025.
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Scaling behaviour of charged particles generated in Xe$-$Xe collisions at $\sqrt{s_{\rm{NN}}}$ = 5.44 TeV using the AMPT model
Authors:
Zarina Banoo,
Ramni Gupta,
Salman K. Malik,
Fakhar Ul Haider,
Balwan Singh,
Sheetal Sharma
Abstract:
The spatial configurations of particles produced in the kinematic phase space during a heavy-ion collision reflect the characteristics of the system created in the collision. The scaling behaviour of the multiplicity fluctuations is studied for the charged particles generated in Xe--Xe collisions at $\sqrt{s_{\rm{NN}}}$ = 5.44 TeV using the String Melting (SM) mode of the AMPT (A Multi-Phase Trans…
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The spatial configurations of particles produced in the kinematic phase space during a heavy-ion collision reflect the characteristics of the system created in the collision. The scaling behaviour of the multiplicity fluctuations is studied for the charged particles generated in Xe--Xe collisions at $\sqrt{s_{\rm{NN}}}$ = 5.44 TeV using the String Melting (SM) mode of the AMPT (A Multi-Phase Transport) model. The scaling behaviour of the normalized factorial moments ($F_\text{q}$) give significant information about the dynamics of the systems under study. A linear power-law growth of the $F_\text{q}$ with the increasing phase space resolution, termed as intermittency, is investigated. The anomalous fractal dimension $D_\text{q}$ is determined, which is linked to the self-similarity and fractal nature of the particle emission spectra, a dependence of which on the order of the moment ($q$) is characterised by the intermittency index ($\varphi_{\text{q}}$). Relating $q^{\rm{th}}$ order Normalised Factorial Moment (NFM) with $F_{2}$, the scaling exponent ($ν$) is determined that quantifies the dynamics of the system created by these collisions and is analyzed for its dependence on the transverse momentum bin width ($Δp_\text{T}$). A comparative study of experimental and model results may help to understand the dynamics of multiparticle production in the heavy-ion collisions.
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Submitted 18 August, 2025;
originally announced August 2025.
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Lattice study of correlators for quarkonium decay
Authors:
Saumen Datta,
Debasish Banerjee,
Nora Brambilla,
Marc Janer,
Viljami Leino,
Julian Mayer-Steudte,
Peter Petreczky,
Balbeer Singh,
Antonio Vairo
Abstract:
While there has been a lot of progress in developing a
formalism for the study of quarkonia in QGP, a nonperturbative
study is still difficult. For bottomonia, where the system size
is much less than the inverse temperature, the interaction of the
system with the medium can be approximated by a dipole interaction with
the color electric field. The decay of the quarkonia can be connected…
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While there has been a lot of progress in developing a
formalism for the study of quarkonia in QGP, a nonperturbative
study is still difficult. For bottomonia, where the system size
is much less than the inverse temperature, the interaction of the
system with the medium can be approximated by a dipole interaction with
the color electric field. The decay of the quarkonia can be connected to
a correlation function of the color electric field.
We present preliminary results from a lattice study of the relevant color
electric field correlator. The structure of the correlator, and its
difference from the corresponding correlator studied for heavy quark
diffusion, is discussed.
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Submitted 27 June, 2025;
originally announced June 2025.
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Study of octupole deformations in Pb-Pb collisions at 5.02 TeV
Authors:
Saraswati Pandey,
B. K. Singh
Abstract:
In this letter, we present the study of the role of octupole deformation in non-spherical nuclei in most-central Pb--Pb collisions at the LHC energy regime. The sensitivity of octupole deformation $β_3$ to the QGP observables is presented by employing the Monte Carlo HYDJET++ model. Motivated by the discrepancies in the $v_2$-to-$v_3$ puzzle found in Pb--Pb collisions and the low-energy nuclear st…
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In this letter, we present the study of the role of octupole deformation in non-spherical nuclei in most-central Pb--Pb collisions at the LHC energy regime. The sensitivity of octupole deformation $β_3$ to the QGP observables is presented by employing the Monte Carlo HYDJET++ model. Motivated by the discrepancies in the $v_2$-to-$v_3$ puzzle found in Pb--Pb collisions and the low-energy nuclear structure calculations of nuclear deformation, we studied the first basic observables necessary for any study in heavy-ion collisions. Using the HYDJET++ framework, we calculate the pseudorapidity distribution, transverse momentum ($p_{\mathrm{T}}$) spectra, and average anisotropic flow ($v_2$ and $v_3$) of primary charged hadrons with different parameters in two geometrical configurations: body-body and tip-tip types of Pb--Pb collisions. The kinematic ranges $0 < p_{\mathrm{T}} < 20~\mathrm{GeV}/c$ and $|η| < 0.8$ are considered. We observe that the charged hadron multiplicity and transverse momentum spectra are dependent on the strength of the octupole deformation parameter. The $\langle v_2 \rangle$ and $\langle v_3 \rangle$ in body-body collisions show a weak positive correlation with $β_3$, while the average anisotropic flow in tip-tip collisions is weakly correlated with $β_3$ in the most-central collision region.
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Submitted 5 May, 2025;
originally announced May 2025.
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ToMCCA-3: A realistic 3-body coalescence model
Authors:
Maximilian Mahlein,
Bhawani Singh,
Michele Viviani,
Francesca Bellini,
Laura Fabbietti,
Alejandro Kievsky,
Laura Elisa Marcucci
Abstract:
The formation of light nuclei in high-energy collisions provides valuable insights into the underlying dynamics of the strong interaction and the structure of the particle-emitting source. Understanding this process is crucial not only for nuclear physics but also for astrophysical studies, where the production of rare antinuclei could serve as a probe for new physics. This work presents a three-b…
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The formation of light nuclei in high-energy collisions provides valuable insights into the underlying dynamics of the strong interaction and the structure of the particle-emitting source. Understanding this process is crucial not only for nuclear physics but also for astrophysical studies, where the production of rare antinuclei could serve as a probe for new physics. This work presents a three-body coalescence model based on the Wigner function formalism, offering a refined description of light-nucleus production. By incorporating realistic two- and three-body nuclear interaction potentials constrained by modern scattering and femtoscopic correlation data, our approach improves on traditional coalescence models. The framework is validated using event generators applied to proton-proton collisions at $\sqrt{s}=13$ TeV to predict the momentum spectra of light (anti) nuclear nuclei with mass number $A=3$, which are then compared with the experimental data from ALICE. Our results demonstrate the sensitivity of light nucleus yields to the choice of nuclear wave functions, emphasizing the importance of an accurate description of the coalescence process. This model lays the foundation for the extension of coalescence studies of $A=3$ light nuclei to a wider range of collision systems and energies.
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Submitted 3 April, 2025;
originally announced April 2025.
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Open quantum system approach to inclusive jet production in heavy-ion collisions
Authors:
Yacine Mehtar-Tani,
Felix Ringer,
Balbeer Singh,
Varun Vaidya
Abstract:
We derive a factorization formula for inclusive jet production in heavy-ion collisions using the tools of Effective Field Theory (EFT). We show how physics at widely separated scales in this process can be systematically separated by matching to EFTs at successively lower virtualities. Owing to a strong scale separation, we recover a vacuum-like DGLAP evolution above the jet scale, while the addit…
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We derive a factorization formula for inclusive jet production in heavy-ion collisions using the tools of Effective Field Theory (EFT). We show how physics at widely separated scales in this process can be systematically separated by matching to EFTs at successively lower virtualities. Owing to a strong scale separation, we recover a vacuum-like DGLAP evolution above the jet scale, while the additional low-energy scales induced by the medium effectively probe the internal structure of the jet. As a result, the cross section can be written as a series with an increasing number of subjets characterized by perturbative matching coefficients each of which is convolved with a {\it distinct} function. These functions encode broadening, medium-induced radiations as well as quantum interference such as the Landau-Pomeranchuk-Migdal effect and color coherence dynamics to all orders in perturbation theory. As a first application of this EFT framework, we investigate the case of an unresolved jet and show how the cross section can be factorized and fully separate the jet dynamics from the universal physics of the medium. To compare to the existing literature, we explicitly compute the medium jet function at next-to-leading order in the coupling and leading order in medium opacity.
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Submitted 31 March, 2025;
originally announced April 2025.
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Separating non-collective effects in d-Au collisions
Authors:
Satya Ranjan Nayak,
Akash Das,
B. K. Singh
Abstract:
In this letter, we present the multiplicity and yields of charged hadrons and particle ratios in d-Au collisions at $\sqrt{s_{NN}}= 200$ GeV using the PYTHIA8/Angantyr. The model reproduces the multiplicity ($N_{ch}$) and pseudo-rapidity distribution reasonably well in minimum-biased d-Au collisions without assuming the formation of a thermalized medium. The invariant yield from Angantyr underpred…
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In this letter, we present the multiplicity and yields of charged hadrons and particle ratios in d-Au collisions at $\sqrt{s_{NN}}= 200$ GeV using the PYTHIA8/Angantyr. The model reproduces the multiplicity ($N_{ch}$) and pseudo-rapidity distribution reasonably well in minimum-biased d-Au collisions without assuming the formation of a thermalized medium. The invariant yield from Angantyr underpredicts the data in central collisions. We discussed the similarity between the nuclear modification factor $R_{AA}$ and data/MC from Angantyr and the possibility of using it as an alternative to check in-medium effects. The data/MC suggests that the central d-Au collisions exhibit signals like baryon enhancement, but no high $p_T$ suppression was found. The d-Au collisions have a much smaller invariant yield than the thermal model calculation for similar $N_{part}$. Based on the available data and simulation results, we argue that a medium may form in the central d-Au collision, but it differs from the perfect QGP formed in Pb-Pb collisions at LHC.
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Submitted 28 June, 2025; v1 submitted 29 March, 2025;
originally announced March 2025.
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Exploiting $ν$-dependence of projected energy correlators in HICs
Authors:
Ankita Budhraja,
Balbeer Singh
Abstract:
We extend the recently derived factorization formula for energy-energy correlators to study the analytic structure of general $ν$-point projected energy correlators in heavy ion collisions. The $ν$-point projected energy correlators (or, $ν$-correlators) are an analytically continued family of the integer $N$-point projected energy correlators, which probe correlations between $N$ final-state part…
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We extend the recently derived factorization formula for energy-energy correlators to study the analytic structure of general $ν$-point projected energy correlators in heavy ion collisions. The $ν$-point projected energy correlators (or, $ν$-correlators) are an analytically continued family of the integer $N$-point projected energy correlators, which probe correlations between $N$ final-state particles. By tracking the largest separation ($χ$) between the $N$ particles, in vacuum, their structure is closely related to the DGLAP splitting functions and exhibits a classical scaling behavior $\sim 1/χ$ which is modified by resummation through the anomalous dimensions. We show that, in a thermal medium, the $ν$-correlators display non-trivial angular scaling already at the leading order in perturbation theory. We find that for non-integer values, particularly $ν<1$, medium-induced jet function is enhanced compared to $ν>1$. This is particularly manifested in the ratios of $ν$-correlators with respect to the two-point energy correlator which encode an intrinsic angular information for $ν<1$ when compared to large $ν$ values. Moreover, for small-$ν$ values, the $ν$-correlators appear to saturate at $ν=0.01$. We further confirm our leading-order numerical computations against simulated events from JEWEL for the parton level production cross-section. Finally, we qualitatively discuss the effect of BFKL resummation for various values of $ν$.
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Submitted 25 March, 2025;
originally announced March 2025.
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Towards factorization with emergent scales for jets in dense media
Authors:
Balbeer Singh,
Varun Vaidya
Abstract:
Employing the recently developed open quantum system Effective Field Theory framework, we investigate jet production and evolution in a dense nuclear medium in electron-ion/heavy-ion collisions. We confirm that the frequent monitoring of the jet by the medium leads to the emergence of a perturbative transverse momentum scale, often referred to as the saturation scale that necessitates further fact…
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Employing the recently developed open quantum system Effective Field Theory framework, we investigate jet production and evolution in a dense nuclear medium in electron-ion/heavy-ion collisions. We confirm that the frequent monitoring of the jet by the medium leads to the emergence of a perturbative transverse momentum scale, often referred to as the saturation scale that necessitates further factorization to completely isolate the non-perturbative physics of the medium. A part of this goal is achieved in this paper by providing an operator definition for the broadening probability of a gluon in the medium within the Markovian approximations. We show that this distribution is (semi)universal; it depends on the angular measurement on the jet and probes both the large and small $x$ dynamics of the medium. We further elucidate all other contributions to non-perturbative physics suggesting that the parameterization of non-perturbative physics is more complex than previously assumed and outline steps required for a complete factorization of the jet production cross section.
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Submitted 25 December, 2024;
originally announced December 2024.
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Factorization for jet production in heavy-ion collisions
Authors:
Yacine Mehtar-Tani,
Felix Ringer,
Balbeer Singh,
Varun Vaidya
Abstract:
We develop an Effective Field Theory approach for jet observables in heavy-ion collisions, where the jet is treated as an open quantum system interacting with a hot and dense QCD medium. Within this framework, we derive a novel factorization formula for inclusive jet production, expressed as a series expansion with an increasing number of radiating subjet functions that encode forward scattering w…
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We develop an Effective Field Theory approach for jet observables in heavy-ion collisions, where the jet is treated as an open quantum system interacting with a hot and dense QCD medium. Within this framework, we derive a novel factorization formula for inclusive jet production, expressed as a series expansion with an increasing number of radiating subjet functions that encode forward scattering with the Quark-Gluon Plasma, convolved with perturbative matching coefficients. This work provides a systematic framework for computing jet observables at higher order and understanding their non-perturbative aspects, paving the way for future applications in heavy-ion phenomenology.
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Submitted 9 September, 2024;
originally announced September 2024.
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Quarkonia dissociation at finite magnetic field in the presence of momentum anisotropy
Authors:
Indrani Nilima,
Mujeeb Hasan,
B. K. Singh,
Mohammad Yousuf Jamal
Abstract:
In this study, we investigate the potential of heavy quarkonia within a magnetized hot QGP medium having finite momentum anisotropy. The phenomenon of inverse magnetic catalysis is introduced into the system, influencing the magnetic field-modified Debye mass and thereby altering the effective quark masses. Concurrently, the impact of momentum anisotropy in the medium is considered that influence…
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In this study, we investigate the potential of heavy quarkonia within a magnetized hot QGP medium having finite momentum anisotropy. The phenomenon of inverse magnetic catalysis is introduced into the system, influencing the magnetic field-modified Debye mass and thereby altering the effective quark masses. Concurrently, the impact of momentum anisotropy in the medium is considered that influence the particle distribution in the medium. The thermal decay width and dissociation temperature of quarkonium states, specifically the 1S and 2S states of charmonium and bottomonium, are computed. Our results reveal that both momentum anisotropy and the inverse magnetic catalysis effects play a significant role in modifying the thermal decay width and dissociation temperature of these heavy quarkonia states.
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Submitted 12 February, 2024;
originally announced February 2024.
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Predicting Quadrupole deformation via anisotropic flow and transverse momentum spectra in isotopic $\mathbf{\prescript{128-135}{54}{\mathrm{Xe}}}$ collisions at LHC
Authors:
Saraswati Pandey,
B. K. Singh
Abstract:
In the hydrodynamical description of heavy-ion collisions, the elliptic flow $\mathrm{v_{2}}$ and triangular flow $\mathrm{v_{3}}$ are sensitive to the quadrupole deformation $\mathrm{β_{2}}$ of the colliding nuclei. We produce $\mathrm{v_{2}}$ and $\mathrm{v_{3}}$ ratios qualitatively and quantitatively in most-central Xe-Xe collisions at 5.44 TeV. By employing HYDJET++ model, we study the sensit…
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In the hydrodynamical description of heavy-ion collisions, the elliptic flow $\mathrm{v_{2}}$ and triangular flow $\mathrm{v_{3}}$ are sensitive to the quadrupole deformation $\mathrm{β_{2}}$ of the colliding nuclei. We produce $\mathrm{v_{2}}$ and $\mathrm{v_{3}}$ ratios qualitatively and quantitatively in most-central Xe-Xe collisions at 5.44 TeV. By employing HYDJET++ model, we study the sensitivity of anisotropic flow coefficients and mean transverse momentum to the quadrupole deformation and system-size in isotopic Xe-Xe collisions. Flow observables strongly depend on the strength of nucleon-nucleon scattering occuring in even-A and odd-A nuclei. Flow for odd-A nuclei is suppressed in comparison to flow in even-A collisions. There exists a linear inter-dependence between $\mathrm{p_{T}}$ integrated anisotropic flow and nuclear deformation. Mean transverse momentum signifies the fireball temperature in body-body and tip-tip collisions. There exists a negative linear correlation of $\mathrm{\langle p_{T} \rangle}$ with collision system-size and a positive correlation with nuclear deformation. Flow measurements in high-energy, heavy-ion collisions using isotopic collision systems, offer a new precision tool to study nuclear structure physics. Observation of nuclear structure properties like nuclear deformation in a heavy-ion collision such as this would be very interesting.
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Submitted 10 December, 2023;
originally announced December 2023.
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Role of three-body dynamics in nucleon-deuteron correlation functions
Authors:
M. Viviani,
S. König,
A. Kievsky,
L. E. Marcucci,
B. Singh,
O. Vázquez Doce
Abstract:
Correlation functions of hadrons can be accessed in high-energy collisions of atomic nuclei, revealing information about the underlying interaction. This work complements experimental efforts to study nucleon-deuteron $Nd$ -- with $N=p$ (proton) or $N=n$ (neutron) -- correlations with theory evaluations using different techniques. The correlation functions $C_{nd}$ and $C_{pd}$ are calculated base…
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Correlation functions of hadrons can be accessed in high-energy collisions of atomic nuclei, revealing information about the underlying interaction. This work complements experimental efforts to study nucleon-deuteron $Nd$ -- with $N=p$ (proton) or $N=n$ (neutron) -- correlations with theory evaluations using different techniques. The correlation functions $C_{nd}$ and $C_{pd}$ are calculated based on scattering wave function, extending previous benchmarks for the $Nd$ scattering matrix to this new observable. We use hyperspherical harmonics and Faddeev techniques with one of the widely used nucleon-nucleon ($NN$) interactions, the Argonne $v_{18}$ potential. Moreover, in the low-energy region we perform additional calculations in the framework of pionless effective field theory. The $pd$ correlation function is computed in the large-energy region to make contact with a recent measurement by the ALICE Collaboration. We show that the scattering wave function has the proper dynamical input to describe an initial rise and subsequent oscillations of $C_{pd}$ as a function of the energy. Effects on the observables using different $NN$ and three-nucleon potentials are evaluated with the conclusion that variations of around $2\%$ are observed. Although these effects are small, future measurements can go beyond this accuracy allowing for new detailed studies of strong interaction in light nuclear systems. The present study supports the current efforts devoted to the measurement of correlation functions in systems dominated by the strong interactions, such as $pd$, $ppp$, $Λd$ and $ppΛ$.
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Submitted 4 June, 2023;
originally announced June 2023.
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Hot QCD White Paper
Authors:
M. Arslandok,
S. A. Bass,
A. A. Baty,
I. Bautista,
C. Beattie,
F. Becattini,
R. Bellwied,
Y. Berdnikov,
A. Berdnikov,
J. Bielcik,
J. T. Blair,
F. Bock,
B. Boimska,
H. Bossi,
H. Caines,
Y. Chen,
Y. -T. Chien,
M. Chiu,
M. E. Connors,
M. Csanád,
C. L. da Silva,
A. P. Dash,
G. David,
K. Dehmelt,
V. Dexheimer
, et al. (149 additional authors not shown)
Abstract:
Hot QCD physics studies the nuclear strong force under extreme temperature and densities. Experimentally these conditions are achieved via high-energy collisions of heavy ions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). In the past decade, a unique and substantial suite of data was collected at RHIC and the LHC, probing hydrodynamics at the nucleon scale, the…
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Hot QCD physics studies the nuclear strong force under extreme temperature and densities. Experimentally these conditions are achieved via high-energy collisions of heavy ions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). In the past decade, a unique and substantial suite of data was collected at RHIC and the LHC, probing hydrodynamics at the nucleon scale, the temperature dependence of the transport properties of quark-gluon plasma, the phase diagram of nuclear matter, the interaction of quarks and gluons at different scales and much more. This document, as part of the 2023 nuclear science long range planning process, was written to review the progress in hot QCD since the 2015 Long Range Plan for Nuclear Science, as well as highlight the realization of previous recommendations, and present opportunities for the next decade, building on the accomplishments and investments made in theoretical developments and the construction of new detectors. Furthermore, this document provides additional context to support the recommendations voted on at the Joint Hot and Cold QCD Town Hall Meeting, which are reported in a separate document.
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Submitted 30 March, 2023;
originally announced March 2023.
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Review of magnetic- and antimagnetic-rotational structures in nuclei
Authors:
Sushil Kumar,
Sukhjeet Singh,
Balraj Singh,
Amita,
Ashok Kumar Jain
Abstract:
This work is an update of the 2000 publication of magnetic-rotational bands by Amita et al. [1], followed by an unpublished update of 2006 [2], and reviews detailed experimental data extracted from original publications for 228 magnetic-rotational (MR or Shears) structures spread over 117 nuclides, and 40 antimagnetic-rotational (AMR) structures in 28 nuclei, with a brief commentary about each ban…
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This work is an update of the 2000 publication of magnetic-rotational bands by Amita et al. [1], followed by an unpublished update of 2006 [2], and reviews detailed experimental data extracted from original publications for 228 magnetic-rotational (MR or Shears) structures spread over 117 nuclides, and 40 antimagnetic-rotational (AMR) structures in 28 nuclei, with a brief commentary about each band. Many of these nuclei are located at or near the semi-magic nucleon numbers, mostly for protons. For example, 88 MR bands are currently known for the Pb (Z=82) nuclei, and 29 AMR band in Pd, Cd and In nuclei. It is interesting that the proton magic numbers appear to play a major role in the MR phenomenon, which seems less well understood. A brief discussion of the salient features of the MR and AMR bands and their theoretical interpretation has been presented in the present review. The tables contain gamma-ray energies, associated level energies with spins and parities, level lifetimes, B(M1), B(E2), and B(M1)/B(E2) ratios and probable spherical quasiparticle configurations. We find that many bands claimed in the literature as MR and AMR bands still have tentative assignments, as level lifetimes, thus B(M1) and B(E2) values, for a large number of MR and AMR bands, which can potentially provide critical criteria for firm identification of such structures, are lacking. Additionally, theoretical model calculations for many of these bands, which could provide insight for a better description of nuclear structure, are also lacking in literature. While this review is mainly based on original research articles, nuclear structure databases ENSDF [3], XUNDL [4], and NSR [5] have been consulted for completeness. The literature cut-off date March 31, 2025.
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Submitted 31 May, 2025; v1 submitted 1 March, 2023;
originally announced March 2023.
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Atlas of Nuclear Isomers -- Second Edition
Authors:
Swati Garg,
Bhoomika Maheshwari,
Balraj Singh,
Yang Sun,
Alpana Goel,
Ashok Kumar Jain
Abstract:
We present an updated version of the 2015-Atlas of Nuclear Isomers \cite{jain2015}, compiling and evaluating experimental data for the isomers with half-life $\ge 10$ $\it{ns}$, together with their spectroscopic properties such as excitation-energies, half-lives, decay modes, spins and parities, energies and multipolarities of isomeric transitions, along with the relevant original references in li…
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We present an updated version of the 2015-Atlas of Nuclear Isomers \cite{jain2015}, compiling and evaluating experimental data for the isomers with half-life $\ge 10$ $\it{ns}$, together with their spectroscopic properties such as excitation-energies, half-lives, decay modes, spins and parities, energies and multipolarities of isomeric transitions, along with the relevant original references in literature. The current version of Atlas presents many re-evaluated half-lives as compared to the 2015 edition, where values were referred to Nuclear Data Sheets publications, when no new data existed. The ENSDF database \cite{Ensdf}, together with the XUNDL \cite{Xundl} and the NUBASE2020 \cite{Kondev2021} databases have been consulted for completeness, yet, data from original papers from journals were considered in the present evaluation, and the NSR bibliographic database \cite{Nsr} has been searched to ensure that this work is as complete and current as possible. Several useful systematic features of nuclear isomers covered in this Atlas have been discussed. Literature cutoff date for the extraction of data is October 31, 2022.
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Submitted 12 December, 2022; v1 submitted 1 August, 2022;
originally announced August 2022.
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Systematic Trends of 0$^+_2$, 1$^-_1$, 3$^-_1$ and 2$^+_1$ Excited States in Even-Even Nuclei
Authors:
B. Pritychenko,
B. Singh,
M. Verpelli
Abstract:
The spin and parity ($J^π$) assignments in even-even nuclei were reviewed across the nuclear chart using the Evaluated Nuclear Structure Data File (ENSDF). The prevalence of 2$^+_1$ first or lowest excited states is confirmed. The properties of 0$^+_2$, 1$^-_1$, and 3$^-_1$ lowest excited states were reexamined using the ENSDF data evaluation procedures. The $J^π$ systematic trends and correlation…
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The spin and parity ($J^π$) assignments in even-even nuclei were reviewed across the nuclear chart using the Evaluated Nuclear Structure Data File (ENSDF). The prevalence of 2$^+_1$ first or lowest excited states is confirmed. The properties of 0$^+_2$, 1$^-_1$, and 3$^-_1$ lowest excited states were reexamined using the ENSDF data evaluation procedures. The $J^π$ systematic trends and correlations between level quantum numbers and nuclear physics phenomena are discussed.
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Submitted 15 July, 2022;
originally announced July 2022.
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Investigating the predicted breathing-mode excitation of the Hoyle state
Authors:
K. C. W. Li,
F. D. Smit,
P. Adsley,
R. Neveling,
P. Papka,
E. Nikolskii,
J. W. Brümmer,
L. M. Donaldson,
M. Freer,
M. N. Harakeh,
F. Nemulodi,
L. Pellegri,
V. Pesudo,
M. Wiedeking,
E. Z. Buthelezi,
V. Chudoba,
S. V. Förtsch,
P. Jones,
M. Kamil,
J. P. Mira,
G. G. O'Neill,
E. Sideras-Haddad,
B. Singh,
S. Siem,
G. F. Steyn
, et al. (3 additional authors not shown)
Abstract:
Knowledge of the low-lying monopole strength in $\mathrm{^{12}C}$ $-$ the Hoyle state in particular $-$ is crucial for our understanding of both the astrophysically important $3α$ reaction and of $α$-particle clustering. Multiple theoretical models have predicted a breathing mode of the Hoyle State at $E_{x} \approx 9$ MeV, corresponding to a radial in-phase oscillation of the underlying $α$ clust…
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Knowledge of the low-lying monopole strength in $\mathrm{^{12}C}$ $-$ the Hoyle state in particular $-$ is crucial for our understanding of both the astrophysically important $3α$ reaction and of $α$-particle clustering. Multiple theoretical models have predicted a breathing mode of the Hoyle State at $E_{x} \approx 9$ MeV, corresponding to a radial in-phase oscillation of the underlying $α$ clusters. The $\mathrm{^{12}C}(α, α^{\prime})\mathrm{^{12}C}$ and $\mathrm{^{14}C}(p, t)\mathrm{^{12}C}$ reactions were employed to populate states in $^{12}$C in order to search for this predicted breathing mode. A self-consistent, simultaneous analysis of the inclusive spectra with R-matrix lineshapes, together with angular distributions of charged-particle decay, yielded clear evidence for excess monopole strength at $E_{x} \approx 9$ MeV which is highly collective. Reproduction of the experimentally observed inclusive yields using a fit, with consistent population ratios for the various broad states, required an additional source of monopole strength. The interpretation of this additional monopole resonance as the breathing-mode excitation of the Hoyle state would provide evidence supporting a $\mathcal{D}_{3h}$ symmetry for the Hoyle state itself. The excess monopole strength may complicate analysis of the properties of the Hoyle state, modifying the temperature dependence of the $3α$ rate at $T_{9} \gtrsim 2$ and ultimately, the predicted nucleosynthesis in explosive stars.
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Submitted 25 January, 2022;
originally announced January 2022.
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Science Requirements and Detector Concepts for the Electron-Ion Collider: EIC Yellow Report
Authors:
R. Abdul Khalek,
A. Accardi,
J. Adam,
D. Adamiak,
W. Akers,
M. Albaladejo,
A. Al-bataineh,
M. G. Alexeev,
F. Ameli,
P. Antonioli,
N. Armesto,
W. R. Armstrong,
M. Arratia,
J. Arrington,
A. Asaturyan,
M. Asai,
E. C. Aschenauer,
S. Aune,
H. Avagyan,
C. Ayerbe Gayoso,
B. Azmoun,
A. Bacchetta,
M. D. Baker,
F. Barbosa,
L. Barion
, et al. (390 additional authors not shown)
Abstract:
This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams, providing access to those regions in the nucleon…
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This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams, providing access to those regions in the nucleon and nuclei where their structure is dominated by gluons. Moreover, polarized beams in the EIC will give unprecedented access to the spatial and spin structure of the proton, neutron, and light ions. The studies leading to this document were commissioned and organized by the EIC User Group with the objective of advancing the state and detail of the physics program and developing detector concepts that meet the emerging requirements in preparation for the realization of the EIC. The effort aims to provide the basis for further development of concepts for experimental equipment best suited for the science needs, including the importance of two complementary detectors and interaction regions.
This report consists of three volumes. Volume I is an executive summary of our findings and developed concepts. In Volume II we describe studies of a wide range of physics measurements and the emerging requirements on detector acceptance and performance. Volume III discusses general-purpose detector concepts and the underlying technologies to meet the physics requirements. These considerations will form the basis for a world-class experimental program that aims to increase our understanding of the fundamental structure of all visible matter
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Submitted 26 October, 2021; v1 submitted 8 March, 2021;
originally announced March 2021.
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The observation of vibrating pear shapes in radon nuclei: update
Authors:
P. A. Butler,
L. P. Gaffney,
P. Spagnoletti,
J. Konki,
M. Scheck,
J. F. Smith,
K. Abrahams,
M. Bowry,
J. Cederkäll,
T. Chupp,
G. De Angelis,
H. De Witte,
P. E. Garrett,
A. Goldkuhle,
C. Henrich,
A. Illana,
K. Johnston,
D. T. Joss,
J. M. Keatings,
N. A. Kelly,
M. Komorowska,
T. Kröll,
M. Lozano,
B. S. Nara Singh,
D. O'Donnell
, et al. (19 additional authors not shown)
Abstract:
There is a large body of evidence that atomic nuclei can undergo octupole distortion and assume the shape of a pear. This phenomenon is important for measurements of electric-dipole moments of atoms, which would indicate CP violation and hence probe physics beyond the standard model of particle physics. Isotopes of both radon and radium have been identified as candidates for such measurements. Her…
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There is a large body of evidence that atomic nuclei can undergo octupole distortion and assume the shape of a pear. This phenomenon is important for measurements of electric-dipole moments of atoms, which would indicate CP violation and hence probe physics beyond the standard model of particle physics. Isotopes of both radon and radium have been identified as candidates for such measurements. Here, we have observed the low-lying quantum states in $^{224}$Rn and $^{226}$Rn by accelerating beams of these radioactive nuclei. We report here additional states not assigned in our 2019 publication. We show that radon isotopes undergo octupole vibrations but do not possess static pear-shapes in their ground states. We conclude that radon atoms provide less favourable conditions for the enhancement of a measurable atomic electric-dipole moment.
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Submitted 10 June, 2020; v1 submitted 23 March, 2020;
originally announced March 2020.
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Evolution of Octupole Deformation in Radium Nuclei from Coulomb Excitation of Radioactive $^{222}$Ra and $^{228}$Ra Beams
Authors:
P. A. Butler,
L. P. Gaffney,
P. Spagnoletti,
K. Abrahams,
M. Bowry,
J. Cederkäll,
G. De Angelis,
H. De Witte,
P. E. Garrett,
A. Goldkuhle,
C. Henrich,
A. Illana,
K. Johnston,
D. T. Joss,
J. M. Keatings,
N. A. Kelly,
M. Komorowska,
J. Konki,
T. Kröll,
M. Lozano,
B. S. Nara Singh,
D. O'Donnell,
J. Ojala,
R. D. Page,
L. G. Pedersen
, et al. (18 additional authors not shown)
Abstract:
There is sparse direct experimental evidence that atomic nuclei can exhibit stable pear shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in radium isotopes, electric octupole ($E3$) matrix elements have been determined for transitions in $^{222,228}$Ra nuclei using the method of sub-barrier, multi-step Coulomb excitation. Beams of the ra…
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There is sparse direct experimental evidence that atomic nuclei can exhibit stable pear shapes arising from strong octupole correlations. In order to investigate the nature of octupole collectivity in radium isotopes, electric octupole ($E3$) matrix elements have been determined for transitions in $^{222,228}$Ra nuclei using the method of sub-barrier, multi-step Coulomb excitation. Beams of the radioactive radium isotopes were provided by the HIE-ISOLDE facility at CERN. The observed pattern of $E$3 matrix elements for different nuclear transitions is explained by describing $^{222}$Ra as pear-shaped with stable octupole deformation, while $^{228}$Ra behaves like an octupole vibrator.
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Submitted 27 January, 2020;
originally announced January 2020.
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Quantifying multinucleon effect in Argon using high-pressure TPC
Authors:
Jaydip Singh,
Srishti Nagu,
Jyotsna Singh,
R. B. Singh
Abstract:
Neutrino oscillation experiments use heavy nuclear targets to achieve sufficient interaction rates. Nuclear effects are introduced in the experimental environment by the use of these targets and need to be quantified as they add to the systematic errors. In the low energy region(around 1 GeV) multinucleon events are also present along with Quasi Elastic(QE) and Delta interactions. Therefore if the…
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Neutrino oscillation experiments use heavy nuclear targets to achieve sufficient interaction rates. Nuclear effects are introduced in the experimental environment by the use of these targets and need to be quantified as they add to the systematic errors. In the low energy region(around 1 GeV) multinucleon events are also present along with Quasi Elastic(QE) and Delta interactions. Therefore if these multinucleon events are not incorporated in the data set properly, we end up with an inaccurate reconstruction of neutrino energy. In our work, we have illustrated the importance of incorporation of multinucleon events for the reduction of systematic errors in physics predictions by DUNE-Near Detector(ND). To achieve this we have presented the event distribution ratio of Ar/C, Ar/Ar, and C/C as a function of squared four-momentum transfer by employing different nuclear models. This analysis recommends the addition of 2p2h or multinucleon events in the event sample and promotes model with Random Phase Approximations(RPA) effect for the analysis of the event sample to overcome or reduce the systematic uncertainties.
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Submitted 17 September, 2020; v1 submitted 20 September, 2019;
originally announced September 2019.
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Density-dependent NN-interaction from subleading chiral 3N-forces: Long-range terms
Authors:
N. Kaiser,
B. Singh
Abstract:
We derive from the subleading contributions to the chiral three-nucleon force (long-range terms, published in Phys.\,Rev.\,C\,77, 064004 (2008)) a density-dependent two-nucleon interaction $V_\text{med}$ in isospin-symmetric, spin-saturated nuclear matter. Following the division of the pertinent 3N-diagrams into two-pion exchange topology, two-pion-one-pion exchange topology and ring topology, we…
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We derive from the subleading contributions to the chiral three-nucleon force (long-range terms, published in Phys.\,Rev.\,C\,77, 064004 (2008)) a density-dependent two-nucleon interaction $V_\text{med}$ in isospin-symmetric, spin-saturated nuclear matter. Following the division of the pertinent 3N-diagrams into two-pion exchange topology, two-pion-one-pion exchange topology and ring topology, we evaluate for these all self-closings and concatenations of nucleon-lines to an in-medium loop. The momentum and $k_f$-dependent potentials associated with the isospin operators ($1$ and $\vecτ_1\!\cdot\!\vecτ_2$) and five independent spin-structures are expressed in terms of functions, which are either given in closed analytical form or require at most one numerical integration. In the same way we treat the $2π$-exchange 3N-force up to fourth order. Our results for $V_\text{med}$ are most helpful to implement the long-range subleading chiral 3N-forces into nuclear many-body calculations.
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Submitted 8 April, 2021; v1 submitted 7 March, 2019;
originally announced March 2019.
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Probing vorticity in heavy ion collision with dilepton production
Authors:
Jitesh R Bhatt,
Hiranmaya Mishra,
Balbeer Singh
Abstract:
We study the effect of vorticity present in heavy ion collisions (HICs) on the temperature evolution of hot quark-gluon plasma in the presence of spin-vorticity coupling. The initial global rotation entails a nontrivial dependence of the longitudinal flow velocity on the transverse coordinates and also develops a transverse velocity component that depends upon the longitudinal coordinate. Both of…
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We study the effect of vorticity present in heavy ion collisions (HICs) on the temperature evolution of hot quark-gluon plasma in the presence of spin-vorticity coupling. The initial global rotation entails a nontrivial dependence of the longitudinal flow velocity on the transverse coordinates and also develops a transverse velocity component that depends upon the longitudinal coordinate. Both of these velocities lead to a 2+1 dimensional expansion of the fireball. It is observed that with finite vorticity and spin-polarization the fireball cools faster as compared to the case without vorticity. Furthermore, we discuss the consequence of this on the production of thermal dileptons.
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Submitted 5 July, 2019; v1 submitted 20 November, 2018;
originally announced November 2018.
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Transverse Momentum Distribution and Elliptic Flow of Charged Hadrons in $U$+$U$ collisions at $\sqrt{s_{NN}}=193$ GeV using HYDJET++
Authors:
Arpit Singh,
P. K. Srivastava,
O. S. K. Chaturvedi,
S. Ahmad,
B. K. Singh
Abstract:
Recent experimental observations of the charged hadron properties in $U+U$ collisions at $193$ GeV contradict many of the theoretical models of particle production including two-component Monte Carlo Glauber model. The experimental results show a small correlation between the charged hadron properties and the initial geometrical configurations (e.g. body-body, tip-tip etc.) of $U+U$ collisions. In…
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Recent experimental observations of the charged hadron properties in $U+U$ collisions at $193$ GeV contradict many of the theoretical models of particle production including two-component Monte Carlo Glauber model. The experimental results show a small correlation between the charged hadron properties and the initial geometrical configurations (e.g. body-body, tip-tip etc.) of $U+U$ collisions. In this article, we have modified the Monte Carlo HYDJET++ model to study the charged hadron production in $U+U$ collisions at $193$ GeV center-of-mass energy in tip-tip and body-body initial configurations. We have modified the hard as well as soft production processes to make this model suitable for $U+U$ collisions. We have calculated the pseudorapidity distribution, transverse momentum distribution and elliptic flow distribution of charged hadrons with different control parameters in various geometrical configurations possible for $U+U$ collision. We find that HYDJET++ model supports a small correlation between the various properties of charged hadrons and the initial geometrical configurations of $U+U$ collision. Further, the results obtained in modified HYDJET++ model regarding $dn_{ch}/dη$ and elliptic flow ($v_{2}$) suitably matches with the experimental data of $U+U$ collisions in minimum bias configuration.
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Submitted 22 May, 2018; v1 submitted 21 July, 2017;
originally announced July 2017.
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Study of charged particle production in $U$-$U$ collisions in a Wounded Quark Model
Authors:
O. S. K. Chaturvedi,
P. K. Srivastava,
Ashwini Kumar,
B. K. Singh
Abstract:
Recently, there has been a growing interest in the study of deformed uranium-uranium ($U$-$U$) collisions in its various geometrical configurations due to their usefulness in understanding the different aspects of quantum chromodynamics (QCD). In this paper we have studied the particle production in deformed $U$-$U$ collisions at $\sqrt{s_{NN}}$ = $193$ GeV using modified wounded quark model (WQM)…
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Recently, there has been a growing interest in the study of deformed uranium-uranium ($U$-$U$) collisions in its various geometrical configurations due to their usefulness in understanding the different aspects of quantum chromodynamics (QCD). In this paper we have studied the particle production in deformed $U$-$U$ collisions at $\sqrt{s_{NN}}$ = $193$ GeV using modified wounded quark model (WQM). At first, we have shown the variation of quark-nucleus inelastic scattering cross-section ($σ_{qA}^{in}$) with respect to centralities for various geometrical orientations of $U$-$U$ collisions in WQM. After that we have calculated the pseudorapidity density ($dn_{ch}/dη$) within WQM using two-component prescription. Further we have calculated the transverse energy density distribution ($dE_{T}/dη$) along with the ratio of transverse energy to charged hadron multiplicity ($E_{T}/N_{ch}$) for $U$-$U$ collisions and compared them with the corresponding experimental data. We have shown the scaling behavior of $dn_{ch}/dη$ and $dE_{T}/dη$ for different initial geometry of $U$-$U$ collision with respect to $p$-$p$ data at $\sqrt{s_{NN}}=200$ GeV. Furthermore we have shown the Bjorken energy density achieved in $U$-$U$ collisions for various configurations and compared them with experimental data of $Au$-$Au$ at 200 GeV. We observe that the present model suitably describes the experimental data for minimum bias geometrical configuration of $U$-$U$ collisions. An estimate for various observables in different initial geometries of $U$-$U$ collisions is also presented which will be tested in future by experimental data.
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Submitted 8 September, 2017; v1 submitted 14 February, 2017;
originally announced February 2017.
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Asymmetric behavior of the B$(E2 \uparrow; 0^+ \rightarrow 2^+)$ values in $^{104-130}$Sn and Generalized Seniority
Authors:
Bhoomika Maheshwari,
Ashok Kumar Jain,
Balraj Singh
Abstract:
We present freshly evaluated B$(E2\uparrow;0^+\rightarrow2^+)$ values across the even-even Sn-isotopes which confirm the presence of an asymmetric behavior as well as a dip in the middle of the full valence space. We explain these features by using the concept of generalized seniority. The dip in the B$(E2)$ values near $^{116}$Sn is understood in terms of a change in the dominant orbits before an…
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We present freshly evaluated B$(E2\uparrow;0^+\rightarrow2^+)$ values across the even-even Sn-isotopes which confirm the presence of an asymmetric behavior as well as a dip in the middle of the full valence space. We explain these features by using the concept of generalized seniority. The dip in the B$(E2)$ values near $^{116}$Sn is understood in terms of a change in the dominant orbits before and after the mid shell, which also explains the presence of asymmetric peaks in the B$(E2)$ values. This approach helps in deciding the most active valence spaces for a given set of isotopes, and single out the most useful truncation scheme for Large Scale Shell Model (LSSM) calculations. The LSSM calculations so guided by generalized seniority are also able to reproduce the experimental data on B$(E2)\uparrow$ values quite well.
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Submitted 11 April, 2016; v1 submitted 28 January, 2016;
originally announced January 2016.
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Decay analysis of compound nuclei with mass A$\sim 30-200$ formed in the reactions involving loosely bound projectiles
Authors:
Mandeep Kaur,
BirBikram Singh,
Manoj K. Sharma,
Raj K. Gupta
Abstract:
The dynamics of the reactions forming compound nuclei using loosely bound projectiles is analysed within the framework of dynamical cluster decay model (DCM) of Gupta and Collaborators. We have analysed different reactions with $^{7}Li$, $^{9}Be$ and $^{7}Be$ as neutron rich and neutron deficient projectiles, respectively, on different targets at the three $E_{lab}$ values, forming compound nuclei…
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The dynamics of the reactions forming compound nuclei using loosely bound projectiles is analysed within the framework of dynamical cluster decay model (DCM) of Gupta and Collaborators. We have analysed different reactions with $^{7}Li$, $^{9}Be$ and $^{7}Be$ as neutron rich and neutron deficient projectiles, respectively, on different targets at the three $E_{lab}$ values, forming compound nuclei within the mass region A$\sim 30-200$. The contributions of light particles LPs ($A\le4$) cross sections $σ_{LP}$, energetically favoured intermediate mass fragments IMFs ($5 \le A_2 \le 20$) cross sections $σ_{IMF}$ as well as fusion-fission $\it{ff}$ cross sections $σ_{ff}$ constitute the $σ_{fus}$ (=$σ_{LP}$+$σ_{IMF}$+$σ_{ff}$) for these reactions. The contribution of the emitted LPs, IMFs and ff fragments is added for all the angular momentum upto the $\ell_{max}$ value, for the resepctive reactions. Interestingly, we find that the $ΔR^{emp}$, the only parameter of model and uniquely fixed to address the $σ_{fus}$ for all other reactions having $\it same$ loosely bound projectile at the chosen incident energy. It may be noted that the dynamical collective mass motion of preformed LPs, IMFs and ff fragments or clusters through the modified interaction potential barrier are treated on parallel footing. We see that the values of modified interaction barrier heights $ΔV_{B}^{emp}$ for such reactions are almost of the same amount specifically at the respective $\ell_{max}$ values.
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Submitted 8 June, 2015;
originally announced June 2015.
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Tables of E2 Transition Probabilities from the first $2^{+}$ States in Even-Even Nuclei
Authors:
B. Pritychenko,
M. Birch,
B. Singh,
M. Horoi
Abstract:
Experimental results of E2 transition probabilities or B(E2) values for the known first 2$^{+}$ states in 447 even-even nuclei have been compiled and evaluated. The evaluation policies for the analysis of experimental data have been described and new results are discussed. The recommended B(E2) values have been compared with comprehensive shell model calculations for a selected set of nuclei, wher…
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Experimental results of E2 transition probabilities or B(E2) values for the known first 2$^{+}$ states in 447 even-even nuclei have been compiled and evaluated. The evaluation policies for the analysis of experimental data have been described and new results are discussed. The recommended B(E2) values have been compared with comprehensive shell model calculations for a selected set of nuclei, where such theoretical procedures are amenable. The present work was motivated by a rapid increase in the number of new B(E2) measurements for the first 2$^{+}$ states since the previous evaluation of such data by S. Raman {\it et al.} published in 2001. Future plans to investigate the systematics of B(E2)$\uparrow$ values, and intercomparison of different experimental techniques to obtain these data are outlined.
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Submitted 12 December, 2016; v1 submitted 20 December, 2013;
originally announced December 2013.
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Particle Production at CBM in a Thermal Model Approach
Authors:
A. Prakash,
P. K. Srivastava,
B. K. Singh
Abstract:
The Compressed Baryonic Matter (CBM) experiment planned at Facility for Antiproton and Ion Research (FAIR) will provide a major scientific effort for exploring the properties of strongly interacting matter in the high baryon density regime. One of the important goal behind such experiment is to precisely determine the equation of state (EOS) for the strongly interacting matter at extreme baryon de…
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The Compressed Baryonic Matter (CBM) experiment planned at Facility for Antiproton and Ion Research (FAIR) will provide a major scientific effort for exploring the properties of strongly interacting matter in the high baryon density regime. One of the important goal behind such experiment is to precisely determine the equation of state (EOS) for the strongly interacting matter at extreme baryon density. In this paper, we have used a thermal model EOS incorporating excluded volume description for the hot and dense hadron gas (HG). We then predict different particle ratios and the total multiplicity of various hadrons in the CBM energy range i.e. from $10$ A GeV to $40$ A GeV lab energies, which corresponds to $4.43$ A GeV and $8.71$ A GeV center-of-mass energies. Our main emphasis is to estimate the strange particles enhancement as well as increase in the net baryon density in CBM experiment. We have also compared our results with the results obtained from various other theoretical approaches existing in the literature such as hadron string dynamics (HSD) model and ultra-relativistic quantum molecular dynamics (UrQMD) etc.
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Submitted 19 August, 2013;
originally announced August 2013.
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Conserved number fluctuations in a hadron resonance gas model
Authors:
P. Garg,
D. K. Mishra,
P. K. Netrakanti,
B. Mohanty,
A. K. Mohanty,
B. K. Singh,
N. Xu
Abstract:
Net-baryon, net-charge and net-strangeness number fluctuations in high energy heavy-ion collisions are discussed within the framework of a hadron resonance gas (HRG) model. Ratios of the conserved number susceptibilities calculated in HRG are being compared to the corresponding experimental measurements to extract information about the freeze-out condition and the phase structure of systems with s…
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Net-baryon, net-charge and net-strangeness number fluctuations in high energy heavy-ion collisions are discussed within the framework of a hadron resonance gas (HRG) model. Ratios of the conserved number susceptibilities calculated in HRG are being compared to the corresponding experimental measurements to extract information about the freeze-out condition and the phase structure of systems with strong interactions. We emphasize the importance of considering the actual experimental acceptances in terms of kinematics (pseudorapidity ($η$) and transverse momentum ($p_{T}$)), the detected charge state, effect of collective motion of particles in the system and the resonance decay contributions before comparisons are made to the theoretical calculations. In this work, based on HRG model, we report that the net-baryon number fluctuations are least affected by experimental acceptances compared to the net-charge and net-strangeness number fluctuations.
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Submitted 12 September, 2013; v1 submitted 26 April, 2013;
originally announced April 2013.
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B(E2) Evaluation for 0+ to 2+ Transitions in Even-Even Nuclei
Authors:
B. Pritychenko,
M. Birch,
M. Horoi,
B. Singh
Abstract:
A collaborative study by Brookhaven-McMaster-Central Michigan is underway to evaluate B(E2)$\uparrow$ for 0$^{+}_{1}$ $\rightarrow$ 2$^{+}_{1}$ transitions. This work is a continuation of a previous USNDP evaluation and has been motivated by a large number of recent measurements and nuclear theory developments. It includes an extended compilation, data evaluation procedures and shell model calcula…
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A collaborative study by Brookhaven-McMaster-Central Michigan is underway to evaluate B(E2)$\uparrow$ for 0$^{+}_{1}$ $\rightarrow$ 2$^{+}_{1}$ transitions. This work is a continuation of a previous USNDP evaluation and has been motivated by a large number of recent measurements and nuclear theory developments. It includes an extended compilation, data evaluation procedures and shell model calculations. The subset of B(E2)$\uparrow$ recommended values for nuclei of relevance to the double-beta decay problem is presented, and evaluation policies of experimental data and systematics are discussed. Future plans for completion of the B(E2;0$^{+}_{1}$ $\rightarrow$ 2$^{+}_{1}$) evaluation project are also described.
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Submitted 8 July, 2014; v1 submitted 27 February, 2013;
originally announced February 2013.
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Wounded Quarks and Multiplicity at Relativistic Ion Colliders
Authors:
Ashwini Kumar,
B. K. Singh,
P. K. Srivastava,
C. P. Singh
Abstract:
In this paper, we propose a parameterization which is based on a phenomenological model involving the wounded quarks interactions for explaining the average charged particle multiplicity $\ < n_{ch}\ >$, the central pseudo-rapidity density $\ < (dn/dη)_{η=0}\ >$ and complete rapidity dependence of $dn/dη$ in relativistic heavy-ion collider experiments. The model also interrelates nucleus-nucleus (…
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In this paper, we propose a parameterization which is based on a phenomenological model involving the wounded quarks interactions for explaining the average charged particle multiplicity $\ < n_{ch}\ >$, the central pseudo-rapidity density $\ < (dn/dη)_{η=0}\ >$ and complete rapidity dependence of $dn/dη$ in relativistic heavy-ion collider experiments. The model also interrelates nucleus-nucleus (A-A) collisions with p-A and p-p interactions. Our parameterization rests on simple assumptions regarding mean number of participating quarks and their average number of collisions. The results for $\ < n_{ch}\ >$ and their variations with the mass number of colliding nuclei, center-of-mass energy ($\sqrt{s_{NN}}$) and collision centrality are well supported by the available experimental data. Finally we give the predictions from our model for A-A collisions at the Large Hadron Collider (LHC) and Compressed Baryonic Matter (CBM) experiments. Our results indicate the existence of a possible universal production mechanism for p-p, p-A and A-A collisions.
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Submitted 25 April, 2013; v1 submitted 4 October, 2012;
originally announced October 2012.
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Deviation from quark-number scaling of the anisotropy parameter v_2 of pions, kaons, and protons in Au+Au collisions at sqrt(s_NN) = 200 GeV
Authors:
A. Adare,
S. Afanasiev,
C. Aidala,
N. N. Ajitanand,
Y. Akiba,
H. Al-Bataineh,
J. Alexander,
K. Aoki,
Y. Aramaki,
E. T. Atomssa,
R. Averbeck,
T. C. Awes,
B. Azmoun,
V. Babintsev,
M. Bai,
G. Baksay,
L. Baksay,
K. N. Barish,
B. Bassalleck,
A. T. Basye,
S. Bathe,
V. Baublis,
C. Baumann,
A. Bazilevsky,
S. Belikov
, et al. (359 additional authors not shown)
Abstract:
Measurements of the anisotropy parameter v_2 of identified hadrons (pions, kaons, and protons) as a function of centrality, transverse momentum p_T, and transverse kinetic energy KE_T at midrapidity (|η|<0.35) in Au+Au collisions at sqrt(s_NN) = 200 GeV are presented. Pions and protons are identified up to p_T = 6 GeV/c, and kaons up to p_T = 4 GeV/c, by combining information from time-of-flight a…
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Measurements of the anisotropy parameter v_2 of identified hadrons (pions, kaons, and protons) as a function of centrality, transverse momentum p_T, and transverse kinetic energy KE_T at midrapidity (|η|<0.35) in Au+Au collisions at sqrt(s_NN) = 200 GeV are presented. Pions and protons are identified up to p_T = 6 GeV/c, and kaons up to p_T = 4 GeV/c, by combining information from time-of-flight and aerogel Cherenkov detectors in the PHENIX Experiment. The scaling of v_2 with the number of valence quarks (n_q) has been studied in different centrality bins as a function of transverse momentum and transverse kinetic energy. A deviation from previously observed quark-number scaling is observed at large values of KE_T/n_q in noncentral Au+Au collisions (20--60%), but this scaling remains valid in central collisions (0--10%).
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Submitted 12 March, 2012;
originally announced March 2012.
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An Update of B(E2) Evaluation for 0+1 -> 2+1 Transitions in Even-Even Nuclei near N~Z~28
Authors:
B. Pritychenko,
J. Choquette,
M. Horoi,
B. Karamy,
B. Singh
Abstract:
An update of B(E2) evaluation for even-even Cr, Fe, Ni and Zn nuclei has been presented. Current update is a continuation of S. Raman work on B(E2) values and was motivated by large numbers of new measurements. It extends the previous evaluation from 20 to 38 nuclei and includes comprehensive shell model analysis. Evaluation policies for analysis of experimental data have been discussed. Future pl…
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An update of B(E2) evaluation for even-even Cr, Fe, Ni and Zn nuclei has been presented. Current update is a continuation of S. Raman work on B(E2) values and was motivated by large numbers of new measurements. It extends the previous evaluation from 20 to 38 nuclei and includes comprehensive shell model analysis. Evaluation policies for analysis of experimental data have been discussed. Future plans for complete B(E2;0+1 -> 2+1) evaluation of even-even nuclei are outlined.
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Submitted 16 May, 2011; v1 submitted 16 February, 2011;
originally announced February 2011.
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Intermediate Mass Fragment Production In Symmetric Collisions
Authors:
Anupriya Jain,
Bahadur Singh,
Suneel Kumar
Abstract:
We present a complete systematic theoretical study of multifragmentation and its associated phenomena in heavy ion collisions. This study is performed within an Isospin dependent Quantum Molecular Dynamical Model (IQMD) and using Minimum Spanning Tree (MST) algorithm. Simulations are carried out to study the different parameters like time evolution of multiplicity, mass distribution, impact parame…
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We present a complete systematic theoretical study of multifragmentation and its associated phenomena in heavy ion collisions. This study is performed within an Isospin dependent Quantum Molecular Dynamical Model (IQMD) and using Minimum Spanning Tree (MST) algorithm. Simulations are carried out to study the different parameters like time evolution of multiplicity, mass distribution, impact parameter dependence and IMF's production dependence of projectile & target mass. The rise and fall in multiplicity of IMF's is observed. Results are compared with experimental data of ALADIN and are found to be in close agreement.
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Submitted 9 February, 2011;
originally announced February 2011.
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Evidence for a spin-aligned neutron-proton paired phase from the level structure of $^{92}$Pd
Authors:
B. Cederwall,
F. Ghazi Moradi,
T. Bäck,
A. Johnson,
J. Blomqvist,
E. Clément,
G. de France,
R. Wadsworth,
K. Andgren,
K. Lagergren,
A. Dijon,
G. Jaworski,
R. Liotta,
C. Qi,
B. M. Nyakó,
J. Nyberg,
M. Palacz,
H. Al-Azri,
A. Algora,
G. de Angelis,
A. Ataç,
S. Bhattacharyya,
T. Brock,
J. R. Brown,
P. Davies
, et al. (32 additional authors not shown)
Abstract:
The general phenomenon of shell structure in atomic nuclei has been understood since the pioneering work of Goeppert-Mayer, Haxel, Jensen and Suess.They realized that the experimental evidence for nuclear magic numbers could be explained by introducing a strong spin-orbit interaction in the nuclear shell model potential. However, our detailed knowledge of nuclear forces and the mechanisms governin…
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The general phenomenon of shell structure in atomic nuclei has been understood since the pioneering work of Goeppert-Mayer, Haxel, Jensen and Suess.They realized that the experimental evidence for nuclear magic numbers could be explained by introducing a strong spin-orbit interaction in the nuclear shell model potential. However, our detailed knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers ($N = Z$), the unique nature of the atomic nucleus as an object composed of two distinct types of fermions can be expressed as enhanced correlations arising between neutrons and protons occupying orbitals with the same quantum numbers. Such correlations have been predicted to favor a new type of nuclear superfluidity; isoscalar neutron-proton pairing, in addition to normal isovector pairing (see Fig. 1). Despite many experimental efforts these predictions have not been confirmed. Here, we report on the first observation of excited states in $N = Z = 46$ nucleus $^{92}$Pd. Gamma rays emitted following the $^{58}$Ni($^{36}$Ar,2$n$)$^{92}$Pd fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution γ-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction. We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling) in the ground and low-lying excited states of the heaviest N = Z nuclei. The strong isoscalar neutron- proton correlations in these $N = Z$ nuclei are predicted to have a considerable impact on their level structures, and to influence the dynamics of the stellar rapid proton capture nucleosynthesis process.
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Submitted 11 January, 2011;
originally announced January 2011.
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Temeprature-dependent Seeger's liquid drop energy for nuclei up to Z=118
Authors:
BirBikram Singh,
Manoj K. Sharma,
Raj Kumar,
Manie Bansal,
Raj K. Gupta
Abstract:
Seeger's semi-empirical mass formula is revisited for two of its constants (bulk constant α(0) and neutron-proton asymmetry constant a_{a}) readjusted to obtain the ground-state (g.s.) binding energies of nuclei within a precision of <1.5 MeV and for nuclei up to Z=118. The aim is to include the temperature T-dependence on experimental binding energies, and not to obtain the new parameter set of S…
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Seeger's semi-empirical mass formula is revisited for two of its constants (bulk constant α(0) and neutron-proton asymmetry constant a_{a}) readjusted to obtain the ground-state (g.s.) binding energies of nuclei within a precision of <1.5 MeV and for nuclei up to Z=118. The aim is to include the temperature T-dependence on experimental binding energies, and not to obtain the new parameter set of Seeger's liquid drop energy VLDM . Our proceedure is to define the g.s. binding energy B = V_{LDM} + δU, as per Strutinsky renormalization procedure, and using the empirical shell corrections δU of Myers and Swiatecki, fit the constants of V_{LDM} to obtain the experimental binding energy Bexpt or theoretically calculated Btheo if data were not available. The T-dependence of the constants of V_{LDM}, is introduced as per the work of Davidson et al., where the pairing energy δ(T) is modified as per new calculations on compound nucleus decays. The newly fitted constants of V_{LDM} at T=0 are made available here for use of other workers interested in nuclear dynamics of hot and rotating nuclei.
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Submitted 2 January, 2011;
originally announced January 2011.
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A new microscopic nucleon-nucleon interaction derived from relativistic mean field theory
Authors:
BirBikram Singh,
M. Bhuyan,
S. K. Patra,
Raj K. Gupta
Abstract:
A new microscopic nucleon-nucleon (NN) interaction has been derived for the first time from the popular relativistic mean field theory (RMFT) Lagrangian. The NN interaction so obtained remarkably relate to the inbuilt fundamental parameters of RMFT. Furthermore, by folding it with the RMFT-densities of cluster and daughter nuclei to obtain the optical potential, it's application is also examined t…
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A new microscopic nucleon-nucleon (NN) interaction has been derived for the first time from the popular relativistic mean field theory (RMFT) Lagrangian. The NN interaction so obtained remarkably relate to the inbuilt fundamental parameters of RMFT. Furthermore, by folding it with the RMFT-densities of cluster and daughter nuclei to obtain the optical potential, it's application is also examined to study the exotic cluster radioactive decays, and results obtained found comparable with the successfully used M3Y phenomenological effective NN interactions. The presently derived NN-interaction can also be used to calculate a number of other nuclear observables.
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Submitted 4 January, 2011; v1 submitted 26 November, 2010;
originally announced November 2010.
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Comparison of IQMD results with experimental data for Sn induced reactions
Authors:
Bahadur Singh,
Suneel Kumar,
Rajeev K. Puri
Abstract:
Here we are comparing our results with experimental data of reactions 57La124+50Sn124, 50Sn124+50Sn124 and 50Sn107+50Sn124 at energy 600 MeV/nucleon. It is observed that IMF's shows the agreement with data at low impact parameters but fails at intermediate impact parameters. We shall try to reproduce the result with reduced cross-section in future.
Here we are comparing our results with experimental data of reactions 57La124+50Sn124, 50Sn124+50Sn124 and 50Sn107+50Sn124 at energy 600 MeV/nucleon. It is observed that IMF's shows the agreement with data at low impact parameters but fails at intermediate impact parameters. We shall try to reproduce the result with reduced cross-section in future.
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Submitted 27 September, 2010;
originally announced September 2010.