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Probing vorticity through femtoscopic correlations
Authors:
Oleh Savchuk,
Pawel Danielewicz,
Daniel Kincses,
Agnieszka Sorensen
Abstract:
In heavy-ion collisions, as the two nuclei pass through one another and create hot and dense matter, part of their initial angular momentum is transferred to the fireball, generating a nonzero average vorticity. Understanding heavy-ion collision dynamics and its influence on key observables, including those used to probe the initial state or assess thermodynamics of nuclear matter, requires unders…
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In heavy-ion collisions, as the two nuclei pass through one another and create hot and dense matter, part of their initial angular momentum is transferred to the fireball, generating a nonzero average vorticity. Understanding heavy-ion collision dynamics and its influence on key observables, including those used to probe the initial state or assess thermodynamics of nuclear matter, requires understanding the magnitude of effects tied to vorticity. In this work, we use simulations of non-central Au+Au collisions at $E_{\rm{kin}}=1.23~A\rm{GeV}$ to show that the rotation of the system impacts the space-time picture of particle emission and, in particular, leaves imprints on proton-pion femtoscopic correlations. Next, we use coarse-graining of the simulation outputs to extract the collective velocity as a function of position and time, shedding light on the dynamical origin of this effect. Moreover, we demonstrate that the displacement between the proton and pion emission centers quantifies the strength of the rotation and propose it as a new signal of vorticity in heavy-ion collisions.
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Submitted 12 October, 2025;
originally announced October 2025.
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Long Range Plan: Dense matter theory for heavy-ion collisions and neutron stars
Authors:
Alessandro Lovato,
Travis Dore,
Robert D. Pisarski,
Bjoern Schenke,
Katerina Chatziioannou,
Jocelyn S. Read,
Philippe Landry,
Pawel Danielewicz,
Dean Lee,
Scott Pratt,
Fabian Rennecke,
Hannah Elfner,
Veronica Dexheimer,
Rajesh Kumar,
Michael Strickland,
Johannes Jahan,
Claudia Ratti,
Volodymyr Vovchenko,
Mikhail Stephanov,
Dekrayat Almaalol,
Gordon Baym,
Mauricio Hippert,
Jacquelyn Noronha-Hostler,
Jorge Noronha,
Enrico Speranza
, et al. (39 additional authors not shown)
Abstract:
Since the release of the 2015 Long Range Plan in Nuclear Physics, major events have occurred that reshaped our understanding of quantum chromodynamics (QCD) and nuclear matter at large densities, in and out of equilibrium. The US nuclear community has an opportunity to capitalize on advances in astrophysical observations and nuclear experiments and engage in an interdisciplinary effort in the theo…
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Since the release of the 2015 Long Range Plan in Nuclear Physics, major events have occurred that reshaped our understanding of quantum chromodynamics (QCD) and nuclear matter at large densities, in and out of equilibrium. The US nuclear community has an opportunity to capitalize on advances in astrophysical observations and nuclear experiments and engage in an interdisciplinary effort in the theory of dense baryonic matter that connects low- and high-energy nuclear physics, astrophysics, gravitational waves physics, and data science
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Submitted 7 November, 2022; v1 submitted 3 November, 2022;
originally announced November 2022.
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Hadronic Transport Model with a Phase Transition
Authors:
P. Danielewicz,
P. -B. Gossiaux,
R. A. Lacey
Abstract:
We specify a tractable transport model with thermodynamic properties close to those expected for the strongly interacting matter. In particular, at high temperatures, the matter undergoes a phase transition, such as to the quark-gluon plasma, with a drop in masses of elementary excitations and a rapid increase in the number of degrees of freedom. We show that a softening of the equation of state…
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We specify a tractable transport model with thermodynamic properties close to those expected for the strongly interacting matter. In particular, at high temperatures, the matter undergoes a phase transition, such as to the quark-gluon plasma, with a drop in masses of elementary excitations and a rapid increase in the number of degrees of freedom. We show that a softening of the equation of state such as associated with the transition to quark-gluon plasma should be observable in the elliptic-flow excitation function from heavy-ion reactions.
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Submitted 6 August, 1998;
originally announced August 1998.
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Partons in Phase Space
Authors:
David A. Brown,
Pawel Danielewicz
Abstract:
Within QED, we examine several issues related to constructing a parton-model-based QCD transport theory. We rewrite the QED analog of the parton model, the Weizsaecker-Williams Approximation, entirely in terms of phase-space quantities and we study the phase-space photon and electron densities created by a classical point charge. We find that the densities take a distinctive ``source-propagator'…
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Within QED, we examine several issues related to constructing a parton-model-based QCD transport theory. We rewrite the QED analog of the parton model, the Weizsaecker-Williams Approximation, entirely in terms of phase-space quantities and we study the phase-space photon and electron densities created by a classical point charge. We find that the densities take a distinctive ``source-propagator'' form. This form does not arise in a conventional derivation of the semiclassical transport equations because of the overuse of the gradient approximation. We do not apply the gradient approximation and so derive the phase-space analog of the Generalized Fluctuation-Dissipation Theorem. Together, this theorem and the expression for the phase-space particle self-energies give a set of coupled phase-space evolution equations. We illustrate how these evolution equations can be used perturbatively or to derive semiclassical transport equations. Our work relies on phase-space propagators and sources, so we describe them in detail when calculating the photon and electron phase-space densities. We use these tools to discuss the shape of a nucleon's parton cloud.
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Submitted 5 February, 1998; v1 submitted 4 February, 1998;
originally announced February 1998.
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Hanbury-Brown--Twiss Analysis in a Solvable Model
Authors:
G. F. Bertsch,
P. Danielewicz,
M. Herrmann
Abstract:
The analysis of meson correlations by Hanbury-Brown--Twiss interferometry is tested with a simple model of meson production by resonance decay. We derive conditions which should be satisfied in order to relate the measured momentum correlation to the classical source size. The Bose correlation effects are apparent in both the ratio of meson pairs to singles and in the ratio of like to unlike pai…
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The analysis of meson correlations by Hanbury-Brown--Twiss interferometry is tested with a simple model of meson production by resonance decay. We derive conditions which should be satisfied in order to relate the measured momentum correlation to the classical source size. The Bose correlation effects are apparent in both the ratio of meson pairs to singles and in the ratio of like to unlike pairs. With our parameter values, we find that the single particle distribution is too distorted by the correlation to allow a straightforward analysis using pair correlation normalized by the singles rates. An analysis comparing symmetrized to unsymmetrized pairs is more robust, but nonclassical off-shell effects are important at realistic temperatures.
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Submitted 7 September, 1993;
originally announced September 1993.