Di-lepton production in heavy-ion collisions and the QCD phase diagram

Open Physics ◽  
2012 ◽  
Vol 10 (6) ◽  
Author(s):  
Yifei Zhang ◽  
Haojie Xu ◽  
Wangmei Zha ◽  
Qun Wang
Keyword(s):  
Phase Diagram ◽  
Mass Spectra ◽  
Heavy Ion ◽  
Mass Region ◽  
Lepton Production ◽  
Qcd Phase Diagram ◽  
Ion Collisions ◽  
200 Gev ◽  
Star Experiment ◽  
Low Mass

AbstractWe reproduce di-electron spectra in the region of 0 < m e+e < 4 GeV in both minimum bias and central Au+Au collisions at $\sqrt {s_{NN} } $ = 200 GeV measured by the STAR experiment. A cocktail simulation, incorporating STAR acceptance and detector responses, is able to describe the “enhancement” of the low mass region by including an in-medium modification of vector mesons and a thermal di-lepton calculation. We also predict the di-lepton mass spectra in RHIC lower energies via an extrapolation method. The evolution of Di-lepton mass spectra, effective temperature, and possible medium modifications versus colliding energies are studied to explore the QCD phase diagram.

STAR Heavy-ion results

2020 ◽  
pp. 2040007
Author(s):  
David Tlusty
Keyword(s):  
Phase Diagram ◽  
Nuclear Physics ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collider ◽  
Qcd Phase Diagram ◽  
Ion Collisions ◽  
Dense Nuclear Matter ◽  
Star Experiment ◽  
Future Plans

The exploration of the Quantum Chromodynamics (QCD) phase diagram has been one of the main drivers of contemporary nuclear physics. Heavy-ion collisions provide a powerful tool to explore phase structures of strongly interacting hot and dense nuclear matter called Quark–Gluon Plasma (QGP). The Relativistic Heavy Ion Collider (RHIC) is uniquely suited to map the QCD phase diagram by varying the energy of collisions, as well as nuclei species. These proceedings discuss the most recent results from the STAR experiment at RHIC and future plans.

scholarly journals Effects of Superstatistics on the Location of the Effective QCD Critical End Point

2019 ◽  
Vol 64 (8) ◽  
pp. 665
Author(s):  
A. Ayala ◽  
M. Hentschinski ◽  
L. A. Hernández ◽  
M. Loewe ◽  
R. Zamora
Keyword(s):  
Phase Diagram ◽  
Chemical Potential ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Chiral Symmetry Restoration ◽  
Interaction Volume ◽  
Qcd Phase Diagram ◽  
End Point ◽  
Ion Collisions ◽  
Effective Description

Effects of the partial thermalization during the chiral symmetry restoration at the finite temperature and quark chemical potential are considered for the position of the critical end point in an effective description of the QCD phase diagram. We find that these effects cause the critical end point to be displaced toward larger values of the temperature and lower values of the quark chemical potential, as compared to the case where the system can be regarded as completely thermalized. These effects may be important for relativistic heavy ion collisions, where the number of subsystems making up the whole interaction volume can be linked to the finite number of participants in the reaction.

scholarly journals Isentropic evolution of the matter in heavy-ion collisions and the search for the critical endpoint

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Mario Motta ◽  
Rainer Stiele ◽  
Wanda Maria Alberico ◽  
Andrea Beraudo
Keyword(s):  
Phase Diagram ◽  
Heavy Ion Collisions ◽  
Dense Matter ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Qcd Phase Diagram ◽  
Ion Collisions ◽  
Momentum Spectra ◽  
Beam Energy Scan ◽  
Near Future

Abstract We study the isentropic evolution of the matter produced in relativistic heavy-ion collisions for various values of the entropy-per-baryon ratio of interest for the ongoing and future experimental searches for the critical endpoint (CEP) in the QCD phase diagram: these includes the current beam-energy-scan (BES) program at RHIC and the fixed-target collisions foreseen for the near future at various facilities. We describe the hot-dense matter through two different effective Lagrangians: the PNJL (Polyakov–Nambu–Jona–Lasinio) and the PQM (Polyakov-quark-meson) models. We focus on quantities expected to have a direct experimental relevance: the speed of sound, responsible for the collective acceleration of the fireball, and the generalized susceptibilities, connected to the cumulants of the distributions of conserved charges. In principle they should affect the momentum spectra and the event-by-event fluctuations of the yields of identified particles. Taking realistic values for the initial temperature and the entropy-per-baryon ratio we study the temporal evolution of the above quantities looking for differences along isentropic trajectories covering different regions of the QCD phase diagram, passing far or close to the CEP or even intersecting the first-order critical line.

scholarly journals Reconstruction of neutral-triggered charged recoil jets in √s = 200 GeV p+p collisions at the STAR experiment

2020 ◽  
Vol 235 ◽  
pp. 05005
Author(s):  
Derek Anderson
Keyword(s):  
Energy Loss ◽  
Path Length ◽  
Heavy Ion ◽  
Particle Dynamics ◽  
Dense Medium ◽  
Direct Photons ◽  
Ion Collisions ◽  
200 Gev ◽  
Star Experiment ◽  
Shed Light

Jets — collimated sprays of hadrons — are produced by hard-scattered partons during the early stages of heavy ion collisions. Hence, they provide a valuable probe of the complex multi-particle dynamics within the hot, dense medium produced in such collisions. In particular, the study of jets recoiling from direct photons (γdir+jet) and those recoiling from energetic π0 (π0+jet) may shed light on the path-length and initial flavor (quark vs. gluon) dependence of the energy-loss experienced by a parton as it traverses the medium. We present here measurements of the yields of charged recoil jets tagged by γdir and π0 in p+p collisions at √S = 200 GeV. These measurements will serve as a vacuum fragmentation reference for an upcoming measurement in Au + Au collisions.

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