We argue that large fluctuations in the saturation momentum are necessary to explain the ATLAS and ALICE data on pA collisions measured at the LHC. Using a form for the distribution of fluctuations motivated by theoretical studies of the non-linear evolution equations for the Color Glass Condensate, we find a remarkably good agreement between theory and the measured distributions. If the saturation momentum fluctuates, we argue that the cross section for a proton probe should also fluctuate, consistent with previous observations. Finally we discuss these results and their possible consistency with what is known about multiplicity fluctuations in such collisions, and attempts to describe the ridge effect from properties of the initial state.
Centrality, rapidity, and transverse-momentum dependence of gluon shadowing and antishadowing on $J/ψ$ production in $d$Au collisions at $\sqrt{s}$=200 GeV
Long-range rapidity correlations in high energy AA collisions in Monte Carlo model with string fusion
基于色偶极元碰撞的图像,在非Glauber Monte Carlo弦-部分子模型的框架下,研究了作为弦融合和渗透现象特征的两个分离快度窗口中观测量之间的长程关联的大小.在有和没有弦融合的情况下得到的预测表明,色弦融合对LHC上Pb-Pb碰撞中的观测量的影响:如果应用足够有效的中心性估计,则n-n相关系数随着中心性和负pt-n相关性而减小。在一般情况下,n-n和pt-n相关系数的值强烈地依赖于碰撞中心固定的方法。相比之下,对pt-pt关联的预测几乎没有中心性确定方法的影响,相应的实验数据将产生强烈的限制弦的横向半径。
Centrality, Rapidity and Transverse-Momentum Dependence of Cold Nuclear Matter Effects on J/Psi Production in d+Au, Cu+Cu and Au+Au Collisions at sqrt(s_NN)=200 GeV
A study on the prompt photon production within the QCD color dipole picture with emphasis in $pp$ and $pA$ collisions at the LHC energy regimes is performed. We present predictions for the differential cross section as a function of photon transverse momentum at different rapidity bins considering updated phenomenological color dipole models, which take into account the QCD gluon saturation physics. The results are directly compared to the recent experimental measurements provided by CMS and ATLAS Collaborations, showing a reasonable agreement in all rapidity bins with no free parameters. Spec…
We studied the centrality selection effect on cumulants (up to fourth order) and the cumulants ratios of net-proton multiplicity distributions in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 7.7, 19.6 and 200 GeV from UrQMD model. The net-proton cumulants are calculated with collision centralities by using charged particle multiplicity from different pesudorapidity ($η$) region. By comparing the results from various collision centralities, we found that the autocorrelation effects are not significant in the results with collision centralities "refmult-3" and "refmult-2", which are using mid-…
We investigate the centrality-dependent validity of the limiting-fragmentation hypothesis in relativistic heavy-ion collisions at energies reached at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). A phenomenological analysis of Au-Au and Pb-Pb collisions within a three-source relativistic diffusion model (RDM) is performed at sqrt(s_NN) = 19.6, 62.4, 130, 200, 2760 and 5023 GeV using four centrality cuts at each energy. Linear and nonlinear expressions for the rapidity drift function are tested and their physical relevance is discussed. Our results are compatib…
Prompt photon production in hadronic collisions at the RHIC and the LHC energies is investigated within the QCD color dipole approach. Predictions for the nuclear modification factor in $pA$ collisions are evaluated based on parton saturation framework and the results are compared to the experimental measurements as a function of the photon transverse momentum at different rapidity bins. The reliability of the models is performed with the data from PHENIX, ATLAS, and ALICE Collaborations. Moreover, we show that the observed $x_T$-scaling of prompt photon production in $pp$ and $pA$ collisions …
Can pion spectra in Pb+Pb collisions at CERN SPS energies be described by those in p+p reactions and energy-momentum conservation ? Rapidity distributions of pions in p+p and Pb+Pb collisions at CERN SPS energies