Centrality-dependent direct photonptspectra inAu+Aucollisions at the BNL Relativistic Heavy Ion Collider (RHIC) energysNN=200 GeV

2009 ◽  
Vol 79 (1) ◽  
Author(s):  
Fu-Ming Liu ◽  
Tetsufumi Hirano ◽  
Klaus Werner ◽  
Yan Zhu
Keyword(s):  
Heavy Ion ◽  
Relativistic Heavy Ion Collider ◽  
200 Gev

scholarly journals Coherent diffractive photoproduction of ρ0 mesons on gold nuclei at 200 GeV/nucleon-pair at the Relativistic Heavy Ion Collider

2017 ◽  
Vol 96 (5) ◽  
Author(s):  
L. Adamczyk ◽  
J. K. Adkins ◽  
G. Agakishiev ◽  
M. M. Aggarwal ◽  
Z. Ahammed ◽  
...  
Keyword(s):  
Heavy Ion ◽  
Nucleon Pair ◽  
Relativistic Heavy Ion Collider ◽  
200 Gev

Physics of particle collisions at high energies: Limits to phenomenology, Part 1

2008 ◽  
Vol 86 (7) ◽  
pp. 883-897 ◽  
Author(s):  
G Sau ◽  
S K Biswas ◽  
B De ◽  
P Guptaroy ◽  
A Bhattacharya ◽  
...  
Keyword(s):  
Good Description ◽  
Heavy Ion ◽  
High Energy ◽  
Data Sets ◽  
Particle Interactions ◽  
Power Law Model ◽  
Particle Collisions ◽  
Relativistic Heavy Ion Collider ◽  
High Energies ◽  
200 Gev

Interpretation and understanding of high-energy PP data in a clear, consistent, and comprehensive manner is crucial for making valid claims to build up any successful theoretical framework for particle interactions. We have tried here to analyze the various sets of PP data available from the pre-ISR days to the latest PP collisions at the relativistic heavy ion collider (RHIC) experiment at [Formula: see text] = 200 GeV in the light of a power-law model. Both mid-rapidity and high-rapidity data sets have been dealt with by applying the same working formula. It is found that the working formula used provides a good description of these wide ranging data sets; but hardly throws any deep insights into the nature of particle interactions that force us to question the worth and rigour of phenomenological studies.PACS Nos.: 13.60.Hb, 13.60.Le, 13.85.Ni

scholarly journals Coherent e+e- production at very low transverse momentum at STAR

2018 ◽  
Vol 171 ◽  
pp. 18016 ◽  
Author(s):  
Chi Yang
Keyword(s):  
Theoretical Model ◽  
Transverse Momentum ◽  
Pair Production ◽  
Spectral Function ◽  
Model Calculation ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collider ◽  
200 Gev ◽  
Star Detector

We report the measurements of e+e- pair production at very low e+e- pair transverse momentum (pT < 0.15 GeV/c) in Au+Au collisions at [see formula in PDF] = 200 GeV and U+U collisions at [see formula in PDF] = 193 GeV using the STAR detector at the Relativistic Heavy Ion Collider. In 60-80% centrality, significant excesses are observed with respect to hadronic cocktails in both Au+Au and U+U collisions. These excess yields can not be explained by a theoretical model calculation incorporating in-medium broadened ρ spectral function. Additionally, the [see formula in PDF] distribution for excess yield is shown and found to be exponential at very low pT.

scholarly journals Gluon polarization measurements from longitudinally polarized proton-proton collisions at STAR

2020 ◽  
Vol 1643 (1) ◽  
pp. 012184
Author(s):  
Zilong Chang
Keyword(s):  
Spin Asymmetry ◽  
Center Of Mass ◽  
Heavy Ion ◽  
Proton Spin ◽  
Gluon Polarization ◽  
Relativistic Heavy Ion Collider ◽  
Center Of Mass Energy ◽  
Double Spin ◽  
200 Gev ◽  
Inclusive Jet

Abstract The gluon polarization contribution to the proton spin is an integral part to solve the longstanding proton spin puzzle. At the Relativistic Heavy Ion Collider (RHIC), the STAR experiment has measured jets produced in mid-pseudo-rapidity, |η| < 1.0, and full azimuth, ϕ, from longitudinally polarized pp collisions to study the gluon polarization in the proton. At center of mass energies s = 200 and 510 GeV, jet production is dominated by hard QCD scattering processes such as gluon-gluon (gg) and quark-gluon (qg), thus making the longitudinal double-spin asymmetry (ALL ) sensitive to the gluon polarization. Early STAR inclusive jet ALL results at s = 200 GeV provided the first evidence of the non-zero gluon polarization at momentum fraction x > 0.05. The higher center of mass energy s = 510 GeV allows to explore the gluon polarization as low as x ∼ 0.015. In this talk we will present the recent STAR inclusive jet and dijet ALL results at s = 510 GeV, and discuss the relevant new analysis techniques for the estimation of trigger bias and reconstruction uncertainty, the underlying event correction on the jet energy and its effect on jet ALL . Dijet results are shown for different topologies in regions of pseudo-rapidity, effectively scanning the x-dependence of the gluon polarization.

scholarly journals The dijet mass distribution in heavy ion collisions

2020 ◽  
Vol 235 ◽  
pp. 05006
Author(s):  
Jared Reiten
Keyword(s):  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Jet Quenching ◽  
Heavy Flavor ◽  
Relativistic Heavy Ion Collider ◽  
Mass Distributions ◽  
Ion Collisions ◽  
Heavy Quark Mass ◽  
200 Gev ◽  
Momentum Imbalance

In these proceedings, we review the production of both light and heavy flavor dijets in heavy ion collisions and highlight a promising observable to expose their distinct signatures. We propose the modification of dijet invariant mass distributions in heavy ion collisions as a new observable that exhibits striking sensitivity to the heavy quark mass dependence of in-medium parton showers. This observable has the advantage of amplifying the effects of jet quenching in contrast to conventional observables, such as the dijet momentum imbalance shift, which involve cancellations of such effects and, hence, result in less pronounced signals. Predictions are presented for Au+Au collisions at √SNN = 200 GeV to guide the future sPHENIX program at the Relativistic Heavy Ion Collider.

scholarly journals Azimuthal Single-Spin Asymmetries of Charged Pions in Jets in s = 200 GeV p↑p Collisions at STAR

2016 ◽  
Vol 40 ◽  
pp. 1660040 ◽  
Author(s):  
J. Kevin Adkins ◽  
James L. Drachenberg
Keyword(s):  
Spin Asymmetry ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collider ◽  
Spin Asymmetries ◽  
Proton Collisions ◽  
Single Spin ◽  
Single Spin Asymmetries ◽  
Polarized Proton ◽  
Charged Pions ◽  
200 Gev

Single spin asymmetry measurements ([Formula: see text]) of the azimuthal distribution of charged pions inside jets produced in transversely polarized proton collisions are sensitive to the transversity distribution and the Collins fragmentation function. The STAR Detector at the Relativistic Heavy Ion Collider is well suited for these types of measurements as it is capable of full jet reconstruction and charged pion identification in the mid-rapidity region ([Formula: see text][Formula: see text][Formula: see text][Formula: see text]). We report here the first observation of Collins [Formula: see text] asymmetries in [Formula: see text] GeV [Formula: see text] collisions.

scholarly journals HADRON SPECTRA IN p+p COLLISIONS AT RHIC AND LHC ENERGIES

2013 ◽  
Vol 28 (16) ◽  
pp. 1350066 ◽  
Author(s):  
P. K. KHANDAI ◽  
P. SETT ◽  
P. SHUKLA ◽  
V. SINGH
Keyword(s):  
Hadron Collider ◽  
Center Of Mass ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collider ◽  
Systematic Analysis ◽  
Center Of Mass Energy ◽  
Hadron Spectra ◽  
200 Gev ◽  
Energy Formula ◽  
Two Parameters

We present the systematic analysis of transverse momentum (pT) spectra of identified hadrons in p+p collisions at Relativistic Heavy Ion Collider ([Formula: see text] and 200 GeV) and at Large Hadron Collider (LHC) energies ([Formula: see text], 2.76 and 7.0 TeV) using phenomenological fit functions. We review various forms of Hagedorn and Tsallis distributions and show their equivalence. We use Tsallis distribution which successfully describes the spectra in p+p collisions using two parameters, Tsallis temperature T which governs the soft bulk spectra and power n which determines the initial production in partonic collisions. We obtain these parameters for pions, kaons and protons as a function of center-of-mass energy [Formula: see text]. It is found that the parameter T has a weak but decreasing trend with increasing [Formula: see text]. The parameter n decreases with increasing [Formula: see text] which shows that production of hadrons at higher energies are increasingly dominated by point like qq scatterings. Another important observation is with increasing [Formula: see text], the separation between the powers for protons and pions narrows down hinting that the baryons and mesons are governed by same production process as one moves to the highest LHC energy.

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