Transverse momentum dependence of semi-inclusive pion production

Cross sections for semi-inclusive electroproduction of charged pions (pi(+/-)) from both proton and deuteron targets were measured for 0.2 < x < 0.5, 2 < Q(2) < 4 GeV(2), 0.3 < z < 1, and P(t)(2) < 0.2 GeV(2). For P(t) < 0.1 GeV, we find the azimuthal dependence to be small, as expected theoretically. For both pi(+) and pi(-), the P(t) dependence from the deuteron is found to be slightly weaker than from the proton. In the context of a simple model, this implies that the initial transverse momenta width of d quarks is larger than for u quarks and, contrary to expectations, the transverse momentum width of the favored fragmentation function is larger than the unfavored one. (C) 2008 Elsevier B.V. All rights reserved.