Transverse momentum dependence of semi-inclusive pion production

Cross sections for semi-inclusive electroproduction of charged pions (π±) from both proton and deuteron targets were measured for 0.2 < x < 0.5, 2 < Q2 < 4 GeV2, 0.3 < z < 1, and Pt2 < 0.2 GeV2. For Pt < 0.1 GeV, we find the azimuthal dependence to be small, as expected theoretically. For both π+ and π-, the Pt 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. © 2008 Elsevier B.V. All rights reserved.