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Register a new userRapidity window dependence of ridge correlations in the glasma
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We study ridge correlations of the glasma in pp collisions at $sqrt{s_{mathrm{NN}}}=7$ TeV by using the color glass condensate (CGC) formalism. The azimuthal collimation at long range rapidity is intrinsic to glasma dynamics and is reproduced here. When rapidity window enlarges, ridge correlations in two dimensional $Delta y$-$Deltaphi$ distribution and one dimensional $Deltaphi$ distribution at long range rapidity gap are enhanced. The enhancements are demonstrated to be the contributions of source gluons. The quantum evolution of the gluons presents unique correlation patterns in differential correlation function. These characters of two gluon correlations open a way of testing the production mechanism from experimental measurements.
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I discuss novel QCD phenomena recently observed in p+p, p+A and A+A collisions, that result from the non-linear dynamics of small-x gluons. I focus on di-hadron correlation measurements, as opposed to single-hadron observables often too inclusive to distinguish possible new effects from established mechanisms. Specifically, I discuss angular correlations of forward di-hadrons in d+Au collisions and long-range rapidity correlations in high-multiplicity p+p and Au+Au collisions.
We investigate the consequences of long range rapidity correlations in the Glasma. Particles produced locally in the transverse plane are correlated by approximately boost invariant flux tubes of longitudinal color electric and magnetic fields that are formed when two sheets of Colored Glass Condensate pass through one another, each acquiring a modified color charge density in the collision. We argue that such long range rapidity correlations persist during the evolution of the Quark Gluon Plasma formed later in the collision. When combined with transverse flow, these correlations reproduce many of the features of the recently observed ridge events in heavy ion collisions at RHIC.
It was recently found that in sulphur-induced nuclear collisions at 200 A GeV the observed strange hadron abundances can be explained within a thermodynamic model where baryons and mesons separately are in a state of relative chemical equilibrium, with overall strangeness being slightly undersaturated, but distributed among the strange hadron channels according to relative chemical equilibrium with a vanishing strange quark chemical potential. We develop a consistent thermodynamic formulation of the concept of relative chemical equilibrium and show how to introduce into the partition function deviations from absolute chemical equilibrium, e.~g.~an undersaturation of overall strangeness or the breaking of chemical equilibrium between mesons and baryons. We then proceed to test on the available data the hypothesis that the strange quark chemical potential vanishes everywhere, and that the rapidity distributions of all the observed hadrons can be explained in terms of one common, rapidity-dependent function $mu_{rm q}(eta)$ for the baryon chemical potential only. The aim of this study is to shed light on the observed strong rapidity dependence of the strange baryon ratios in the NA36 experiment.
The energy and rapidity dependence of the average transverse momentum $langle p_T rangle$ in $pp$ and $pA$ collisions at RHIC and LHC energies are estimated using the Colour Glass Condensate (CGC) formalism. We update previous predictions for the $p_T$ - spectra using the hybrid formalism of the CGC approach and two phenomenological models for the dipole - target scattering amplitude. We demonstrate that these models are able to describe the RHIC and LHC data for the hadron production in $pp$, $dAu$ and $pPb$ collisions at $p_T le 20$ GeV. Moreover, we present our predictions for $langle p_T rangle$ and demonstrate that the ratio $langle p_{T}(y)rangle / langle p_{T}(y = 0)rangle$ decreases with the rapidity and has a behaviour similar to that predicted by hydrodynamical calculations.
The correlation between multiplicities in two separated rapidity windows, the so-called long-range correlation (LRC), is studied in the framework of the model with independent identical emitters. Its shown that the LRC coefficient, defined for the scaled (relative) variables, nevertheless depends on the absolute width of the forward rapidity window and does not depend on the width of the backward one. The dependence of the LRC coefficient on the forward rapidity acceptance is explicitly found with only one theoretical parameter. The preliminary comparison with ALICE 7TeV pp collisions data shows that the multiplicity LRC in the data can be described in the framework of the suggested approach.
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