Event-by-event mean 
                $$\varvec{p}_{\mathbf {T}}$$
                        p
                      T
               fluctuations in pp and Pb–Pb collisions at the LHC

We investigate pseudorapidity correlations of the average transverse flow of particles emitted in relativistic heavy-ion collisions. We employ 3+1 dimensional viscous relativistic hydrodynamics with initial conditions from the quark Glauber Monte Carlo model to confront the recent measurements on the pseudorapidity correlations of the transverse momentum fluctuations in Pb+Pb collisions at √ sNN = 2760 GeV. We find good agreement between the model predictions and data. Further, we study two other observables build with the covariance of the average transverse momentum in different rapidity bins. These observables have better stability under various systematics, thus allowing for a robust comparison between data and model. The transverse flow-transverse flow correlation coefficient is directly related to correlations of the underlying collective flow at different pseudorapidities. The 3-bin measure of pT factorization breaking in pseudorapidity gives an estimate of possible decorrelation of the average transverse flow in the longitudinal direction.

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“…The above quantity shows a very strong centrality dependence, similar to the scaled transverse momentum fluctuations [35,44]…”

Section: Transverse Flow-transverse Flow Correlation Coefficientmentioning

confidence: 88%

Pseudorapidity profile of transverse momentum fluctuations in heavy ion collisions

Chatterjee

Božek

2017

Phys. Rev. C

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“…Comparisons with NLO pQCD calculations lead to the same disagreement for the η than with the π 0 [5] when CTEQ PDFs and AES [4] for the fragmentation function are used, but the discrepancy is much reduced for π 0 when MSTW PDFs with DSS14 [3] for the fragmentation function are used. Combined with the Pb-Pb measurement at √ s NN = 2.76 TeV [2], these results will allow us to obtain the nuclear modification factor, R AA , for the η meson as well as to extend the π 0 R AA measurement [6] up to 20 GeV/c. Yet differential measurements such as π 0 -hadron correlations are also needed to have a better understanding of the in-medium energy loss.…”

Section: Measurement Of Neutral Meson Productionmentioning

confidence: 89%

Neutral meson production and correlation with charged hadrons in pp and Pb-Pb collisions with the ALICE experiment at the LHC

Vauthier

2017

Nuclear Physics A

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International audienceAmong the probes used to investigate the properties of the Quark-Gluon Plasma, the measurement of the energy loss of high-energy partons can be used to put constraints on energy-loss models and to ultimately access medium characteristics, such as the energy density or the temperature. The study of two-particle correlations allows us to obtain very different constraints compared to the nuclear modification factor. In particular, the correlation of charged hadrons with high energy π0 or direct photons is believed to give a measurement of the parton energy loss and insights into the medium-induced modification of the fragmentation process. High energy neutral pions are reconstructed using the ALICE electromagnetic calorimeters EMCal and PHOS, and the charged particles are detected by the main tracking detectors ITS and TPC. In these proceedings, the measurement of neutral mesons at s=2.76TeV in pp collisions are presented, as well as the measurements of azimuthal π0 -hadron correlations in pp and Pb-Pb collisions at s=2.76TeV , and the extracted per-trigger yield modification factor ( IAA ). Comparisons with theoretical model calculations are also added

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“…A prominent scaling behavior emerges in event-byevent mean p T fluctuations in pp collisions at LHC energies [47][48][49]. In our previous work [43], we studied it focusing only on the energy W = 0.90 TeV, and we did not discuss the GS behavior by extending the analysis to other energies.…”

Section: Normalized Fluctuation Measure Of Transverse Momentummentioning

confidence: 99%

“…The best fit values of the parameters σ and n to the experimental data on the event-by-event fluctuation of mean pT observed by ALICE Collaboration[47] and results of evaluation of κ2 by Eq (18)…”

mentioning

confidence: 98%

Saturation momentum scale extracted from semi-inclusive transverse spectra in high-energy pp collisions

Osada

Kumaoka

2019

Phys. Rev. C

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Geometric scaling is well confirmed for transverse momentum distributions observed in protonproton collisions at LHC energies. We introduced multiplicity dependence on a saturation momentum of the geometrical scaling, assuming the scaling holds for semi-inclusive distributions as well as for inclusive distributions. The saturation momentum is usually given by Bjorken's x variable, but redefinition of the scaling variable can make the saturation momentum a function of collision energy W . We treat the energy as a free parameter (denoted W * to distinguish it from W ) and associate the energy-dependent saturation momentum Qsat(W * ) with particle number density. By using Qsat(W * ) for a scaling variable τ , we show semi-inclusive distributions can be geometrically scaled. i.e., all semi-inclusive spectra observed at W =0.90, 2.76 and 7.00 TeV overlap one universal function. The particle density dependences of mean transverse momentum pT for LHC energies scales in terms of Qsat(W * ). Furthermore, our model explains a scaling property of event-by-event pT fluctuation measure √ Cm/ pT at LHC energies for pp collisions, where Cm is two-particle transverse momentum correlator. Our analysis of the pT fluctuation makes possible to evaluate a non-perturbative coefficient of the gluon correlation function.

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Event-by-event mean $$\varvec{p}_{\mathbf {T}}$$ p T fluctuations in pp and Pb–Pb collisions at the LHC

Cited by 83 publications

References 45 publications

Pseudorapidity profile of transverse momentum fluctuations in heavy ion collisions

Pseudorapidity profile of transverse momentum fluctuations in heavy ion collisions

Neutral meson production and correlation with charged hadrons in pp and Pb-Pb collisions with the ALICE experiment at the LHC

Saturation momentum scale extracted from semi-inclusive transverse spectra in high-energy pp collisions

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