J/psi suppression in p-A collisions from charm quark energy loss in cold nuclear matter

摘要

The energy loss effect of charm quarks in cold nuclear matter on J/psi suppression in p-A collisions is studied. By means of two parametrizations of quark energy loss, the leading-order computations for J/psi production cross section ratios RW(Fe)/Be (x(F)) are presented and compared with the selected E866 experimental data, with the c (c) over bar remaining colored on its entire path in the medium. It is found that the energy loss of the color octet c (c) over bar is an important effect in J/psi suppression; however, whether it is linear or quadratic with the path length cannot be determined. The successful description of J/psi suppression in 0.2 < x(F) < 0.65 gives the charm quark mean energy loss per unit path length alpha = 1.49 +/- 0.37 GeV/fm. Using the same quark energy loss model, we further give the phenomenological analysis at the leading order for J/psi production cross section ratios as a function of y for the Large Hadron Collider experimental data.