STAR Heavy-ion results

Author(s):  
David Tlusty

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.

Open Physics ◽  
2012 ◽  
Vol 10 (6) ◽  
Author(s):  
Yifei Zhang ◽  
Haojie Xu ◽  
Wangmei Zha ◽  
Qun Wang

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.


Author(s):  
Amaresh Jaiswal ◽  
Najmul Haque ◽  
Aman Abhishek ◽  
Raktim Abir ◽  
Aritra Bandyopadhyay ◽  
...  

In this article, there are 18 sections discussing various current topics in the field of relativistic heavy-ion collisions and related phenomena, which will serve as a snapshot of the current state of the art. Section 1 reviews experimental results of some recent light-flavored particle production data from ALICE collaboration. Other sections are mostly theoretical in nature. Very strong but transient magnetic field created in relativistic heavy-ion collisions could have important observational consequences. This has generated a lot of theoretical activity in the last decade. Sections 2, 7, 9, 10 and 11 deal with the effects of the magnetic field on the properties of the QCD matter. More specifically, Sec. 2 discusses mass of [Formula: see text] in the linear sigma model coupled to quarks at zero temperature. In Sec. 7, one-loop calculation of the anisotropic pressure are discussed in the presence of strong magnetic field. In Sec. 9, chiral transition and chiral susceptibility in the NJL model is discussed for a chirally imbalanced plasma in the presence of magnetic field using a Wigner function approach. Sections 10 discusses electrical conductivity and Hall conductivity of hot and dense hadron gas within Boltzmann approach and Sec. 11 deals with electrical resistivity of quark matter in presence of magnetic field. There are several unanswered questions about the QCD phase diagram. Sections 3, 11 and 18 discuss various aspects of the QCD phase diagram and phase transitions. Recent years have witnessed interesting developments in foundational aspects of hydrodynamics and their application to heavy-ion collisions. Sections 12 and 15–17 of this article probe some aspects of this exciting field. In Sec. 12, analytical solutions of viscous Landau hydrodynamics in 1+1D are discussed. Section 15 deals with derivation of hydrodynamics from effective covariant kinetic theory. Sections 16 and 17 discuss hydrodynamics with spin and analytical hydrodynamic attractors, respectively. Transport coefficients together with their temperature- and density-dependence are essential inputs in hydrodynamical calculations. Sections 5, 8 and 14 deal with calculation/estimation of various transport coefficients (shear and bulk viscosity, thermal conductivity, relaxation times, etc.) of quark matter and hadronic matter. Sections 4, 6 and 13 deal with interesting new developments in the field. Section 4 discusses color dipole gluon distribution function at small transverse momentum in the form of a series of Bells polynomials. Section 6 discusses the properties of Higgs boson in the quark–gluon plasma using Higgs–quark interaction and calculate the Higgs decays into quark and anti-quark, which shows a dominant on-shell contribution in the bottom-quark channel. Section 13 discusses modification of coalescence model to incorporate viscous corrections and application of this model to study hadron production from a dissipative quark–gluon plasma.


2008 ◽  
Vol 17 (05) ◽  
pp. 771-801 ◽  
Author(s):  
M. J. TANNENBAUM

The status of the physics of heavy ion collisions is reviewed based on measurements over the past 6 years from the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The dense nuclear matter produced in Au + Au collisions with nucleon-nucleon c.m. energy [Formula: see text] at RHIC corresponds roughly to the density and temperature of the universe a few microseconds after the ‘big-bang’ and has been described as “a perfect liquid” of quarks and gluons, rather than the gas of free quarks and gluons, “the quark-gluon plasma” as originally envisaged. The measurements and arguments leading to this description will be presented.


2015 ◽  
Vol 2015 ◽  
pp. 1-23 ◽  
Author(s):  
Li-Na Gao ◽  
Fu-Hu Liu

We propose a new revised Landau hydrodynamic model to study systematically the pseudorapidity distributions of charged particles produced in heavy ion collisions over an energy range from a few GeV to a few TeV per nucleon pair. The interacting system is divided into three sources, namely, the central, target, and projectile sources, respectively. The large central source is described by the Landau hydrodynamic model and further revised by the contributions of the small target/projectile sources. The modeling results are in agreement with the available experimental data at relativistic heavy ion collider, large hadron collider, and other energies for different centralities. The value of square speed of sound parameter in different collisions has been extracted by us from the widths of rapidity distributions. Our results show that, in heavy ion collisions at energies of the two colliders, the central source undergoes a phase transition from hadronic gas to quark-gluon plasma liquid phase; meanwhile, the target/projectile sources remain in the state of hadronic gas. The present work confirms that the quark-gluon plasma is of liquid type rather than being of a gas type.


1989 ◽  
Vol 04 (15) ◽  
pp. 3717-3757 ◽  
Author(s):  
W. M. GEIST

Basic theoretical ideas on a phase transition in heavy ion collisions to a thermalized plasma of free quarks and gluons are outlined. Major experiments are then described which made use of oxygen and sulphur beams with moderate (BNL) or high (CERN) momenta. Representative results pertaining to both average event features and quark-gluon plasma properties are discussed in some detail. This review addresses also interested non-specialists.


2007 ◽  
Vol 16 (09) ◽  
pp. 2952-2955
Author(s):  
◽  
MAURO R. COSENTINO

Heavy Quarkonium states modifications in relativistic heavy ion collisions have been of great interest since the proposal by Matsui and Satz of J/ψ suppression as a signature of Quark-Gluon Plasma (QGP) formation. Recent studies suggest that the excited states χc, ψ(2 S ) and ϒ(3 S ) melt sequentially1,2 and the amount of observed suppression depends on the state and medium conditions. Therefore, this suppression pattern may be used as a probe of the medium temperature. In this work we present preliminary results on the charmonium and bottomnium measurements performed by the STAR experiment at RHIC for p + p and Cu + Cu collisions at [Formula: see text].


2019 ◽  
Vol 64 (8) ◽  
pp. 665
Author(s):  
A. Ayala ◽  
M. Hentschinski ◽  
L. A. Hernández ◽  
M. Loewe ◽  
R. Zamora

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.


2018 ◽  
Vol 172 ◽  
pp. 05010 ◽  
Author(s):  
Christine Nattrass

The Quark Gluon Plasma (QGP) is created in high energy heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). This medium is transparent to electromagnetic probes but nearly opaque to colored probes. Hard partons produced early in the collision fragment and hadronize into a collimated spray of particles called a jet. The partons lose energy as they traverse the medium, a process called jet quenching. Most of the lost energy is still correlated with the parent parton, contributing to particle production at larger angles and lower momenta relative to the parent parton than in proton-proton collisions. This partonic energy loss can be measured through several observables, each of which give different insights into the degree and mechanism of energy loss. The measurements to date are summarized and the path forward is discussed.


Sign in / Sign up

Export Citation Format

Share Document