Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · hep-ph/9908213

Effects of friction on the chiral symmetry restoration in high energy heavy-ion collisions

M. Ishihara·F. Takagi
View original source ↗Read source document ↗Export metadata ↓

Abstract

We study the effects of friction on the chiral symmetry restoration which may take place temporarily in high energy heavy ion collisions. The equations of motion with friction are introduced to describe the time evolution of the chiral condensates within the framework of the linear $σ$ model. Four types of friction are used to study how the result is sensitive to the choice of the friction. For the thermalization stage, the time dependent temperature is parameterized so as to simulate the result of the parton-cascade model. It is parameterized according to the one dimensional scaling hydrodynamics for the subsequent cooling stage. The time development of the condensates and the entropy production due to friction are calculated numerically. The time interval in which the chiral symmetry is restored approximately is investigated in detail for four types of friction. It is found that; (i) the maximum temperature must be high enough (not lower than 230 MeV) and the friction must be strong enough in order that the chiral symmetry restoration lasts for a long time (not shorter than 3fm/c); (ii) the ratio of time interval in which chiral symmetry is restored, to the time interval in which the temperature is higher than the critical temperature is typically 0.5 when the friction is strong enough; and (iii) the entropy due to the friction is mainly produced in the early stage of the cooling. The effect of freezeout is discussed briefly.

Explore related subjects

hep-phnucl-th

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M. Ishihara, F. Takagi. 1999-10-06. Effects of friction on the chiral symmetry restoration in high energy heavy-ion collisions. https://doi.org/10.1103/physrevc.61.024903

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Neutralino dark matter in gauge mediation

We explore the potential of neutralino dark matter within the framework of gauge-mediated supersymmetry (SUSY) breaking. Gauge mediation offers an advantage over gravity mediation, as SUSY CP/flavor problems are avoided more easily, leading to significantly milder fine-tuning for electroweak symmetry-breaking compared to gravity mediation. In our models, the lightest neutralino, as the lightest SUSY particle (LSP), is a viable dark matter candidate, assuming a gravitino mass of $\mathcal{O}(100)~\mathrm{TeV}$. The models are formulated in five-dimensional space-time, where the SUSY breaking field and the matter fields are placed on separate branes to avoid issues related to flavor and CP violation, and the radion is stabilized by a supersymmetric Goldberger--Wise mechanism. Four distinct neutralino dark matter scenarios are studied: bino-wino coannihilation, higgsino dark matter, wino dark matter, and entropy-diluted bino dark matter. For each case, we determine the allowed parameter spaces and evaluate their consistency with existing experimental limits. Additionally, we examine the potential for testing these models through future investigations at the High-Luminosity Large Hadron Collider (HL-LHC) and through dark matter direct detection experiments.

hep-ph↗
arXiv2026

Models with rank-reducing discrete boundary conditions on $T^2/{\mathbb Z}_4$

We study six-dimensional $SU(n)$ gauge models with rank-reducing discrete boundary conditions on the orbifold $T^2/{\mathbb Z}_4$, without and with continuous Wilson line phases. For the latter case, we find that a minimal model can describe the breakdown of the electroweak symmetry based on an $SU(6)$ gauge group. This model possesses excellent features that two Higgs doublets come from the zero modes of the extra-dimensional gauge field, and the quarks in each generation can be unified into one multiplet, without exotic quarks, as the zero modes of a bulk field in the $\boldsymbol{15}$ representation of $SU(6)$. There exists a vacuum where the electroweak symmetry is slightly broken by the Hosotani mechanism, with the addition of suitable bulk fields.

hep-ph↗
arXiv2026

Supernova cooling from neutrino-devouring dark matter

Supernova cooling provides a powerful probe of physics beyond the Standard Model (SM), in particular for new, light states interacting feebly with SM particles. In this \textit{Letter}, we investigate for the first time the production of fermionic dark matter (DM) via the neutrino-devouring process inside a core-collapse supernova, which contributes to the excessive cooling of the supernova. By incorporating state-of-the-art supernova simulation data and the full time evolution information, we derive stringent and robust limits on DM interactions, which can improve upon direct detection limits by several orders of magnitude. We exclude the cross sections down to $10^{-51}-10^{-58}$~cm$^2$ in the keV-MeV mass range for DM-electron scattering, and $10^{-49}-10^{-56}$~cm$^2$ in the 0.1-100~MeV mass range for DM-nucleon scattering, supplemented by complementary constraints from cosmology, astrophysics, colliders and direct detection experiments in the larger cross section regime. We also close almost the entire window in which fermionic DM constitutes $\mathcal{O}(1)$ fraction of DM due to its coupling to electrons in the keV-MeV mass range.

hep-ph↗