Large-p _p_e_r_p_e_n_d_i_c_u_l_a_r _t_o heavy quark production in two-photon collisions

Abstract

The next-to-leading-order (NLO) cross section for the production of heavy quarks at large transverse momenta (p _p_e_r_p_e_n_d_i_c_u_l_a_r _t_o) in #gamma##gamma# collisions is calculated with perturbative fragmentation functions (PFF's). This approach allows for a resummation of terms #propor to##alpha#_s ln(p _p_e_r_p_e_n_d_i_c_u_l_a_r _t_o "2/m"2) which arise in NLO from collinear emission of gluons by heavy quarks at large p _p_e_r_p_e_n_d_i_c_u_l_a_r _t_o or from almost collinear branching of photons or gluons into heavy-quark pairs. We present single-inclusive distributions in p _p_e_r_p_e_n_d_i_c_u_l_a_r _t_o and rapidity including direct and resolved photons for #gamma##gamma# production of heavy quarks at e"+e"- colliders and at high-energy #gamma##gamma# colliders. The results are compared with the fixed-order calculation for m finite including QCD radiative corrections. The two approaches differ in the definitions and relative contributions of the direct and resolved terms, but essentially agree in their sum. The resummation of the #alpha#_s ln(p _p_e_r_p_e_n_d_i_c_u_l_a_r _t_o "2/m"2) terms in the PFF approach leads to a softer p _p_e_r_p_e_n_d_i_c_u_l_a_r _t_o distribution and to a reduced sensitivity to the choice of the renormalization and factorization scales. (orig.)26 refs.Available from TIB Hannover: RA 2999(95-205) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman