Leading proton production in e(+) p collisions at HERA

Events with a final-state proton carrying a large fraction of the proton beam momentum, x(L) > 0.6, and the square of the transverse momentum p(T)(2) < 0.5 GeV2 T, have been studied in e(+)p collisions with the ZEUS detector at HERA. Data with different photon virtualities were used: Q(2) < 0.02 GeV2, 0.1 < Q(2) < 0.74 GeV2 and 3 < Q(2) < 254 GeV2, corresponding to integrated luminosities of 0.9, 1.85 and 3.38 pb(-1). The cross sections are given as a function of x(L), p(T)(2), Q(2) and the Bjorken scaling variable, x. The ratio of the cross section for leading proton production to the inclusive e(+)p cross section shows only a mild dependence on Q(2) and on x. In the region 0.6 < x(L) < 0.97, the relative yield of protons is only a weak function of x(L). (C) 2003 Elsevier Science B.V. All rights reserved.