PaperPanorama
FAQ

Nuclear Theory·nucl-th

Wednesday·January 27, 2021

7 papers—2 primary·5 cross-listed

All7Primary2Cross-lists5
  1. 01

    Determining the temperature in heavy-ion collisions with multiplicity distribution

    Y. D. Song🇨🇳 · R. Wang🇨🇳 · Y. G. Ma🇨🇳 · X. G. Deng🇨🇳 · H. L. Liu🇨🇳

    By relating the charge multiplicity distribution and the temperature of a de-exciting nucleus through a deep neural network, we propose that the charge multiplicity distribution can be used as a thermometer of heavy-ion collisions. Based on an isospin-dependent quantum molecular dynamics model, we study the caloric curve of reaction Pd + Be with the apparent temperature determined through the charge multiplicity distribution. The caloric curve shows a characteristic signature of nuclear liquid-gas phase transition around the apparent temperature , which is consistent with that through a traditional heavy-ion collision thermometer, and indicates the viability of determining the temperature in heavy-ion collisions with multiplicity distribution.

    nucl-thhep-phnucl-exPLB(2021)·33 citations
  2. 02

    Soft pions and transport near the chiral critical point

    Eduardo Grossi🇺🇸 · Alexander Soloviev🇺🇸 · Derek Teaney🇺🇸 · Fanglida Yan🇺🇸

    During the expansion of a heavy ion collision, the system passes close to the critical point of QCD, and thus the fluctuations of the order parameter are expected to be enhanced. Our goal is to compute how these enhanced fluctuations modify the transport coefficients of QCD near the pseudo-critical point. We also make a phenomenological estimate for how chiral fluctuations could effect the momentum spectrum of soft pions. We first formulate the appropriate stochastic hydrodynamic equations close to the critical point. Then, working in mean field, we determine the correlation functions of the stress tensor and the currents which result from this stochastic real time theory, and use these correlation functions to determine the scaling behavior of the transport coefficients. The hydrodynamic theory also describes the propagation of pion waves, fixing the scaling behavior of the dispersion curve of soft pions. We present scaling functions for the shear viscosity and the charge conductivities near the pseudo-critical point, and estimate the absolute magnitude of the critical fluctuations to these parameters and the bulk viscosity. Using the calculated pion dispersion curve, we estimate the expected critical enhancement of soft pion yields, and this estimate provides a plausible explanation for the excess seen in experiment relative to ordinary hydrodynamic computations. Our results motivate further phenomenological and numerical work on the implications of chiral symmetry on real time properties of thermal QCD near the pseudo-critical point.

    nucl-thhep-phPRD(2021)·63 citations

Affiliations

first authorsco-authorsvia INSPIRE