Quark‐gluon densities in the nuclear fragmentation region in heavy ion collisions at LHC
At the LHC, the leading partons in the nuclei are expected to interact with the maximal possible strength — black disk limit — up to transverse momenta of the order of few GeV. We demonstrate that in this limit the densities of the quark — gluon systems produced in the central AA collisions in the nucleus fragmentation regions should exceed 300GeV/fm3 which is at least as high as the densities discussed for the central region. Experimental signatures of such a regime are also discussed.
Achieving high baryon densities in the fragmentation regions in heavy ion collisions at top RHIC energy
Heavy ion collisions at extremely high energy, such as the top energy at RHIC, exhibit the property of transparency where there is a clear separation between the almost net-baryon-free central rapidity region and the net-baryon-rich fragmentation region. We calculate the net-baryon rapidity loss and the nuclear excitation energy using the energy-momentum tensor obtained from the McLerran-Venugopalan model. Nuclear compression during the collision is further estimated using a simple space-time picture. The results show that extremely high baryon densities, about twenty times larger than the normal nuclear density, can be achieved in the fragmentation regions.
Electron nucleus collisions at THERA
The nuclear option at THERA provides an ideal and unique opportunity to investigate the black body limit (BBL) of high energy Deep Inelastic Scattering of highly virtual photons off heavy nuclear targets and thereby probe QCD in a new regime. At high enough energies, whichever hadronic configuration the photon fluctuates into, the interaction at a given impact parameter with the heavy nuclear target will eventually reach its geometrical limit corresponding to the scattering from a black disk. An attractive feature of the BBL regime for a large nucleus is that the interaction is strong although the coupling constant is small. Predictions for longitudinal and transverse distributions of the leading hadrons in inclusive and diffractive channels and exclusive vector meson production are found to be strikingly different in BBL