scholarly journals Scaling properties of direct photon yields in heavy ion collisions

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Vladimir Khachatryan ◽  
Michał Praszałowicz
Keyword(s):  
Scaling Laws ◽  
Heavy Ion ◽  
Charged Hadron ◽  
Direct Photon ◽  
Recent Analysis ◽  
Scaling Properties ◽  
Ion Collisions ◽  
Phenix Collaboration ◽  
Measurement Results ◽  
Photon Spectra

Abstract A recent analysis from the PHENIX collaboration of available direct photon measurement results in collisions of various systems such as Au+Au, Cu+Cu, and Pb+Pb, at different beam energies ranging from 39 to 2760 GeV, has shown a universal, within experimental uncertainties, multiplicity scaling, in which direct photon $$p_{T}$$pT-spectra for transverse momenta up to 2 GeV/c are scaled with charged hadron pseudorapidity density at midrapidity raised to power $$\alpha =1.25$$α=1.25. On the other hand, those direct photon $$p_{T}$$pT-spectra also exhibit geometrical scaling in the similar $$p_{T}$$pT range. Assuming power-law dependence of the scaled photon spectra for both scaling laws, we formulate two independent conditions for the power $$\alpha $$α, which overshoot experimental data by $$\sim 10\%$$∼10% on average. We discuss possible sources that might improve this estimate.

scholarly journals Direct-Photon Spectra and Anisotropic Flow in Heavy Ion Collisions from Holography

2017 ◽  
Vol 137 ◽  
pp. 07029
Author(s):  
Ioannis Iatrakis ◽  
Elias Kiritsis ◽  
Chun Shen ◽  
Di-Lun Yang
Keyword(s):  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Direct Photon ◽  
Anisotropic Flow ◽  
Ion Collisions ◽  
Photon Spectra

Study the early stage of heavy ion collisions with direct photons

2014 ◽  
Vol 29 ◽  
pp. 1460230 ◽  
Author(s):  
Fu-Ming Liu ◽  
Sheng-Xu Liu
Keyword(s):  
Collective Motion ◽  
Early Stage ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Transverse Momentum Spectrum ◽  
Direct Photons ◽  
Ion Collisions ◽  
Phenix Collaboration ◽  
Early Beginning ◽  
Hadronic Data

Based on the modelling of the collective motion in AuAu collisions at [Formula: see text] at centrality 0-20% and 20-40% and PbPb collisions at [Formula: see text] at centrality 0-40% with a 3+1D event-averaged ideal hydrodynamics constrained with hadronic data, we study the transverse momentum spectrum and elliptic flow of direct photons and find that the recent direct photon data from both PHENIX collaboration at RHIC and ALICE collaboration at LHC favour an early beginning of collective expansion (τ0 < 0.6 fm/c) and a late formation of quark gluon plasma (τ ~ 2 fm/c).

scholarly journals Probing the evolution of heavy-ion collisions using direct photon interferometry

2020 ◽  
Vol 102 (2) ◽  
Author(s):  
Oscar Garcia-Montero ◽  
Nicole Löher ◽  
Aleksas Mazeliauskas ◽  
Jürgen Berges ◽  
Klaus Reygers
Keyword(s):  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Direct Photon ◽  
Ion Collisions

scholarly journals Aspects of Relativistic Heavy-Ion Collisions

Universe ◽  
2020 ◽  
Vol 6 (5) ◽  
pp. 61 ◽  
Author(s):  
Georg Wolschin
Keyword(s):  
Heavy Ion Collisions ◽  
Initial Conditions ◽  
Hadron Collider ◽  
Heavy Ion ◽  
Charged Hadron ◽  
Distribution Functions ◽  
Relativistic Heavy Ion Collisions ◽  
Short Time Scale ◽  
Relativistic Heavy Ion Collider ◽  
Ion Collisions

The rapid thermalization of quarks and gluons in the initial stages of relativistic heavy-ion collisions is treated using analytic solutions of a nonlinear diffusion equation with schematic initial conditions, and for gluons with boundary conditions at the singularity. On a similarly short time scale of t ≤ 1 fm/c, the stopping of baryons is accounted for through a QCD-inspired approach based on the parton distribution functions of valence quarks, and gluons. Charged-hadron production is considered phenomenologically using a linear relativistic diffusion model with two fragmentation sources, and a central gluonic source that rises with ln 3 ( s N N ) . The limiting-fragmentation conjecture that agrees with data at energies reached at the Relativistic Heavy-Ion Collider (RHIC) is found to be consistent with Large Hadron Collider (LHC) data for Pb-Pb at s N N = 2.76 and 5.02 TeV. Quarkonia are used as hard probes for the properties of the quark-gluon plasma (QGP) through a comparison of theoretical predictions with recent CMS, ALICE and LHCb data for Pb-Pb and p-Pb collisions.

scholarly journals Parton energy loss in heavy-ion collisions via direct-photon and charged-particle azimuthal correlations

2010 ◽  
Vol 82 (3) ◽  
Author(s):  
B. I. Abelev ◽  
M. M. Aggarwal ◽  
Z. Ahammed ◽  
A. V. Alakhverdyants ◽  
B. D. Anderson ◽  
...  
Keyword(s):  
Charged Particle ◽  
Energy Loss ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Direct Photon ◽  
Parton Energy Loss ◽  
Azimuthal Correlations ◽  
Ion Collisions

INFLUENCE OF LONG-RANGE CORRELATION ON THE SCALING PROPERTIES OF THE NORMALIZED FACTORIAL CORRELATORS IN RELATIVISTIC HEAVY-ION COLLISIONS

2013 ◽  
Vol 22 (08) ◽  
pp. 1350059 ◽  
Author(s):  
X. Z. BAI ◽  
C. B. YANG
Keyword(s):  
Phase Transition ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collisions ◽  
Ginzburg Landau ◽  
Scaling Properties ◽  
Ion Collisions ◽  
Range Correlation ◽  
Dynamical Fluctuations ◽  
Second Order Phase Transition

The effect of multiplicity correlation between two bins to the dynamical fluctuations is investigated for a second-order phase transition from quark–gluon plasma (QGP) to hadrons, within the Ginzburg–Landau description for the transition. Normalized factorial correlators are used to characterize the dynamical fluctuations. A scaling behavior among the correlators is found, and an approximate universal exponent is obtained with very weak dependence on the details of the phase transition.

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