Fragmentation in Jets: Cone and Threshold Effects
  We study the fragmentation of (light) quarks and gluons to hadrons inside a jet of cone size R. This allows for a more exclusive analysis of fragmentation than is currently the case. The shape of semi-inclusive cross sections in the hadron energy fraction z is described by fragmenting jet functions (FJFs), which we calculate in terms of R and the jet energy E. We introduce a new joint resummation to sum the double logarithms of R and 1-z in the FJFs, which may similarly be applied to initial-state radiation at hadron colliders. Our results at next-to-leading logarithmic order indicate that the resummation of the threshold logarithms of 1-z is already important for z > 0.5 and improves the convergence of perturbation theory. Our framework may be used to analyze LHC and RHIC data and to test and tune Monte Carlo event generators. 
Massimiliano Procura and Wouter J. Waalewijn
hep-ph nucl-th