Large-p(perpendicular to) heavy-quark production in two-photon collisions

The next-to-leading-order (NLO) cross section for the production of heavy quarks at large transverse momenta (p perpendicular to) in gamma gamma collisions is calculated with perturbative fragmentation functions (PFFs). This approach allows for a resummation of terms proportional to alpha(s) In(p(perpendicular to)(2)/m(2)) which arise in NLO from collinear emission of gluons by heavy quarks at large p perpendicular to or from almost collinear branching of photons or gluons into heavy-quark pairs. We present single-inclusive distributions in p perpendicular to 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) In(p(perpendicular to)(2)/m(2)) terms in the PFF approach leads to a softer p perpendicular to distribution and to a reduced sensitivity to the choice of the renormalization and factorization scales.