SEARCH FOR QUARK GLUON PLASMA IN RELATIVISTIC HEAVY ION COLLISIONS

1998 ◽  
pp. 362-378 ◽  
Author(s):  
Chong-Shou Gao
Keyword(s):  
Quark Gluon Plasma ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collisions ◽  
Ion Collisions

JET CONVERSIONS IN QGP AND SUPPRESSION OF IDENTIFIED HADRONS

2007 ◽  
Vol 16 (07n08) ◽  
pp. 1930-1936 ◽  
Author(s):  
WEI LIU ◽  
CHE MING KO ◽  
BEN-WEI ZHANG
Keyword(s):  
Transverse Momentum ◽  
Quark Gluon Plasma ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collisions ◽  
High Transverse Momentum ◽  
Ion Collisions ◽  
Conversion Rates ◽  
Gluon Jets

A gluon or quark jet traversing through a quark-gluon plasma can be converted into a quark or gluon jet through scatterings with thermal partons. Their conversion rates due to two-body elastic and inelastic scattering as well as scatterings involving gluon radiation are evaluated in the lowest order in Quantum Chromodynamics (QCD). Including both energy loss and conversions of quark and gluon jets in the expanding quark-gluon plasma produced in relativistic heavy ion collisions, we find a net conversion of quark jets to gluon jets. This reduces the difference between the nuclear modification factors for quark and gluon jets in central heavy ion collisions and thus enhances the p/π+ and [Formula: see text] ratios at high transverse momentum. Using the larger QCD coupling constant from lattice QCD calculations than that given by the perturbative QCD further enhances the net quark to gluon jet conversion rate, leading to a closer similarity between these ratios at high transverse momentum in central Au + Au collisions at [Formula: see text] and in p + p collisions at same energy as observed in experiments.

scholarly journals Kinetic evolution and correlation of fluctuations in an expanding quark gluon plasma

2018 ◽  
Vol 33 (08) ◽  
pp. 1850040 ◽  
Author(s):  
Golam Sarwar ◽  
Jan-e Alam
Keyword(s):  
Correlation Function ◽  
Power Spectrum ◽  
Quark Gluon Plasma ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collisions ◽  
Thermodynamic Quantities ◽  
Dirac Delta ◽  
Ion Collisions

Evolution of spatially anisotropic perturbation created in the system formed after Relativistic Heavy Ion Collisions has been studied. The microscopic evolution of the fluctuations has been examined within the ambit of Boltzmann Transport Equation (BTE) in a hydrodynamically expanding background. The expansion of the background composed of quark gluon plasma (QGP) is treated within the framework of relativistic hydrodynamics. Spatial anisotropic fluctuations with different geometries have been evolved through Boltzmann equation. It is observed that the trace of such fluctuation survives the evolution. Within the relaxation time approximation, analytical results have been obtained for the evolution of these anisotropies. Explicit relations between fluctuations and transport coefficients have been derived. The mixing of various Fourier (or k) modes of the perturbations during the evolution of the system has been explicitly demonstrated. This study is very useful in understanding the presumption that the measured anisotropies in the data from heavy ion collisions at relativistic energies imitate the initial state effects. The evolution of correlation function for the perturbation in pressure has been studied and shows that the initial correlation between two neighbouring points in real space evolves to a constant value at later time which gives rise to Dirac delta function for the correlation function in Fourier space. The power spectrum of the fluctuation in thermodynamic quantities (like temperature estimated in this work) can be connected to the fluctuation in transverse momentum of the thermal hadrons measured experimentally. The bulk viscous coefficient of the QGP has been estimated by using correlations of pressure fluctuation with the help of Green–Kubo relation. Angular power spectrum of the anisotropies has been estimated in the appendix.

scholarly journals Experimental overview of correlations in small collision systems A brief history

2018 ◽  
Vol 172 ◽  
pp. 05002 ◽  
Author(s):  
Soumya Mohapatra
Keyword(s):  
Strong Evidence ◽  
Quark Gluon Plasma ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collisions ◽  
Collective Phenomena ◽  
Ion Collisions ◽  
Cumulant Method ◽  
Flow Effects

The azimuthal anisotropies of particle yields observed in relativistic heavy ion collisions have been traditionally considered as a strong evidence of the formation of a deconfined quark-gluon plasma in these collisions. However multiple recent measurements in pp and p/D/He+A collisions show similar features as those observed in heavy ion collisions, indicating the possibility of the production of such a deconfined medium in smaller collision systems. This paper presents a comprehensive summary of such measurements in small systems. It includes measurements of identified and inclusive two-particle correlations in ΔΦ and Δη, with different procedures used to subtract the dijet contributions, as well as measurements of multi-particle cumulants cn{2 - 8}. The traditional cumulant measurements confirm presence of collective phenomena in p+A collisions, but are biased by non-flow correlations and are not able to provide evidence for collectivity in pp collisions. To address this, a new subevent cumulant method that further suppresses the contribution non-flow effects was developed, whose measurements are also discussed.

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