Search

We propose a parametrization of the nuclear absorption mechanism relying on the proper time spent by c c ¯ bound states travelling in nuclear matter. Our approach could lead to the extraction of charmonium formation time. It is based on a large amount of proton-nucleus data, from nucleon-nucleon center-of-mass energies s NN = 27 Ge V to s NN = 5.02 Te V , collected in the past 30 years, and for which the main effect on charmonium production must be its absorption by the nuclear matter it crosses. [ABSTRACT FROM AUTHOR]

Novel considerations are presented on the physics, apparatus and accelerator designs for a future, luminous, energy frontier electron-hadron (eh) scattering experiment at the LHC in the thirties for which key physics topics and their relation to the hadron-hadron HL-LHC physics programme are discussed. Demands are derived set by these physics topics on the design of the LHeC detector, a corresponding update of which is described. Optimisations on the accelerator design, especially the interaction region (IR), are presented. Initial accelerator considerations indicate that a common IR is possible to be built which alternately could serve eh and hh collisions while other experiments would stay on hh in either condition. A forward-backward symmetrised option of the LHeC detector is sketched which would permit extending the LHeC physics programme to also include aspects of hadron-hadron physics. The vision of a joint eh and hh physics experiment is shown to open new prospects for solving fundamental problems of high energy heavy-ion physics including the partonic structure of nuclei and the emergence of hydrodynamics in quantum field theory while the genuine TeV scale DIS physics is of unprecedented rank. [ABSTRACT FROM AUTHOR]

We present a new approach to estimate the effect of gluon shadowing in nucleus + nucleus collisions and its consequences on the J/ ψ production yield. Using kinematical information available from the measured J/ ψ production in proton + proton collisions at $\sqrt{s_{NN}}=200$ GeV, we build a Glauber Monte Carlo code which takes into account shadowing in two alternative ways: multiple-scattering corrections or Q2 evolution of parton densities. We exploit the dependence of these different parameterizations to the J/ ψ transverse momentum and we give the first predictions on the resulting pT dependence of the nuclear modification factor in deuteron + gold collisions at the same energy. [ABSTRACT FROM AUTHOR]

One observes strong suppression effects for hard probes, e.g. the production of J/ ψ or high- p T particles, in nucleus–nucleus ( AA) collisions at RHIC. Surprisingly, the magnitude of the suppression is quite similar to that at SPS. In order to establish whether these features arise due to the presence of a thermalized system of quarks and gluons formed in the course of the collision, one should investigate the impact of suppression mechanisms which do not explicitly involve such a state. We calculate shadowing for gluons in the Glauber–Gribov theory and propose a model invoking a rapidity-dependent absorptive mechanism motivated by energy-momentum conservation effects. Furthermore, final-state suppression due to interaction with comoving matter (hadronic or pre-hadronic) has been shown to describe the data at SPS. We extend this model by including the backward reaction channel, i.e. recombination of open charm, which is estimated directly from pp data at RHIC. Strong suppression of charmonium both in pA and AA collisions at LHC is predicted. This is in stark contrast with the predictions of models assuming QGP formation and thermalization of heavy quarks. [ABSTRACT FROM AUTHOR]