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(Color online) Histograms of the average transverse momentum per event for Au+Au at √ s NN = 20, 62, 130, and 200 GeV for the 5% most central collisions at each energy. Both data and mixed events are shown for each incident energy. The lines represent gamma distributions.

(Color online) Histograms of the average transverse momentum per event for Au+Au at √ s NN = 20, 62, 130, and 200 GeV for the 5% most central collisions at each energy. Both data and mixed events are shown for each incident energy. The lines represent gamma distributions.

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Article
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We present results for two-particle transverse momentum correlations, <Delta p(t,i)Delta p(t,j)>, as a function of event centrality for Au+Au collisions at root SNN = 20, 62, 130, and 200 GeV at the BNL Relativistic Heavy Ion Collider. We observe correlations decreasing with centrality that are similar at all four incident energies. The correlation...

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We present results for two-particle transverse momentum correlations, ⟨Δpt,iΔpt,j⟩, as a function of event centrality for Au+Au collisions at √sNN=20, 62, 130, and 200 GeV at the BNL Relativistic Heavy Ion Collider. We observe correlations decreasing with centrality that are similar at all four incident energies. The correlations multiplied by the...

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... Recent advances in heavy-ion collision experiments now enable the isolation of the thermal fluctuations from confounding effects, such as the initial state geometry fluctuations [28][29][30][31][32], flow contributions, and other non-thermal sources, allowing temperature fluctuations to be extracted from EbE mean transverse momentum fluctuations of final-state charged particles [27]. EbE mean transverse momentum fluctuations have been extensively measured across collision energies and systems in various heavy-ion facilities, offering a new avenue to study the QCD phase diagram [31,[33][34][35][36][37][38]. Progress in di-lepton observations also indicates that measurements of vector-meson invariant mass distributions by di-lepton decays can be used to determine the temperature of the thermal source at different ...
... Recent advances in heavy-ion collision experiments now enable the isolation of the thermal fluctuations from confounding effects, such as the initial state geometry fluctuations [28][29][30][31][32], flow contributions, and other non-thermal sources, allowing temperature fluctuations to be extracted from EbE mean transverse momentum fluctuations of final-state charged particles [27]. EbE mean transverse momentum fluctuations have been extensively measured across collision energies and systems in various heavy-ion facilities, offering a new avenue to study the QCD phase diagram [31,[33][34][35][36][37][38]. Progress in di-lepton observations also indicates that measurements of vector-meson invariant mass distributions by di-lepton decays can be used to determine the temperature of the thermal source at different stages of the system evolution [39][40][41][42]. ...
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... However, fluctuations arising in the initial-state of the colliding nuclei also play a major role, a hint of which was obtained from the measurement by the ALICE Collaboration for Pb−Pb collisions at center-of-mass energy per nucleon √ s NN = 2.76 TeV [2]. Recent measurements by the STAR [1,6] and ALICE [2] experiment at RHIC and LHC reported that the strength of dynamical ⟨p T ⟩ fluctuations decreased * subhadeep.roy@cern.ch † tanu.gahlaut@cern.ch ...
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... The dynamical ⟨p T ⟩ fluctuations estimated by variance have been extensively studied in the Super Proton Synchrotron (SPS) [1,[19][20][21][22], Relativistic Heavy-Ion Collider (RHIC) [2,3,[23][24][25], and the Large Hadron Collider (LHC) [4,26,27]. These results reveal a universal multiplicity dependence, where correlations are progressively diluted with increasing participant numbers, consistent with dominance by particle pairs originating from the same nucleon-nucleon collisions. ...
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... Each particle has a random value of p t , chosen, independently for each particle, from an underlying probability distribution, i.e., the p t spectrum, which is a measurable observable at a given collision centrality. The magnitude of the trivial statistical fluctuations can thus be evaluated from law of large numbers: where p t = 0.57 GeV [78]. This corresponds to the the relative fluctuation of the average transverse momentum originating from the simple fact that N is finite. ...
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... Remarkably, the value κ 3 = 0.110 chosen in Fig. 5.7, and which yield an rms v 3 in good agreement with STAR preliminary data, is fully consistent with the correlation between ε 3 and v 3 shown in Fig. C.2 The fact that the coefficients κ 2 and κ 3 chosen for 238 U+ 238 U collisions are reasonable implies that the choices made for 197 Au+ 197 Au collisions, κ 2 = 0.155 and κ 3 = 0.100, are also reasonable. The κ n coefficients are damped by vis- where p t = 0.57 GeV [78]. This corresponds to the the relative fluctuation of the average transverse momentum originating from the simple fact that N is finite. ...
Thesis
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... There are trivial statistical fluctuations of p t , due to the fact that the average is evaluated over a finite sample of particles, but the observed fluctuations are larger. The excess fluctuations are called dynamical fluctuations, and have been measured in Au+Au collisions at √ s NN = 200 GeV [1] and lower energies [2][3][4], and in Pb+Pb collisions at √ s NN = 2.76 TeV [5]. Dynamical p t fluctuations are thought to originate from eventto-event fluctuations at the early stage of the collision. ...
... In Sec. II we show that a hint of this positive skew can be seen in existing STAR data [2] on Au+Au collisions, while it is clearly visible in the results of event-by-event hydrodynamic simulations of Pb+Pb collisions. This constitutes a solid basis for investigating this phenomenon. ...
... VI, where we derive a generic formula relating the skewness of the E 0 distribution to the statistical properties of the initial density field in a perturbative approach [10,11]. Figure 1 displays the histogram of the distribution of p t measured by the STAR collaboration in central Au+Au collisions [2], where p t is evaluated by averaging the transverse momenta of the charged particles observed in the detector. As mentioned in the Introduction, this quantity has trivial fluctuations due to the finite number of particles, typically of order 1000, in every event. ...
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