Obtaining the nuclear gluon distribution from heavy quark decays to leptonpairs in pA collisions

We have studied how lepton pairs from decays of heavy-flavoured mesons prod uced in pA collisions can be used to determine the modifications of the glu on distribution in the nucleus. Since heavy-quark production is dominated b y the gg channel, the ratio of correlated lepton pair cross sections from D (D)over bar and B(B)over bar decays in pA and pp collisions directly reflec ts the ratio R-g(A) drop f(g)(A). We have numerically calculated the lepton -pair cross sections from these decays in pp and pA collisions at SPS, RHIC and LHC energies. We find that ratio of the pA to pp cross sections agrees quite well with the input R-g(A). Thus, sufficiently accurate measurements could be used to determine the nuclear modification of the gluon distribut ion over a greater range of x and Q(2) than presently available, putting st rong constraints on models. (C) 2001 Elsevier Science B.V. All rights reser ved.