COLOR PROPAGATION IN COLD AND HOT MATTER

Abstract

The propagation of color traversing the nuclear medium is studied in mediumenergy semi-inclusive deep inelastic scattering in nuclei and in high energylead-lead collisions, using existing published HERMES data and performinga measurement with the ATLAS detector at the LHC respectively. Differentaspects are analyzed. In the first part two related observables are combinedand modeled using a new geometric model that describes both simultaneously.The model provides information on the transport coefficient and the colorlifetime or production length in the cold medium produced in electron-nucleusscattering at medium energies. In the second part the measurement of theprompt and non-prompt J/u elliptic flow coefficient in lead-lead collisionswith the ATLAS detector at the LHC is performed. This coefficient is anexcellent observable linked to the color lifetime of charm and bottom quarks,probed by measuring the prompt and non-prompt J/u , in the hot densemedium created in high energy nucleus-nucleus collisions.