2007/06/14 by Matthias Neubert, Neubert, Matthias · 1 citation
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.48550/arxiv.0706.2136
26 pages, 5 figures
arxiv created 2007/06/14 · arxiv updated 2009/12/01
Using methods of effective field theory, a systematic analysis of the fragmentation functions Da/H(x,mQ) of a hadron H containing a heavy quark Q is performed (with a=Q,Qbar,q,qbar,g). By integrating out pair production of virtual and real heavy quarks, the fragmentation functions are matched onto a single nonperturbative function describing the fragmentation of the heavy quark Q into the hadron H in "partially quenched" QCD. All calculable, short-distance dependence on x is extracted in this step. For x->1, the remaining fragmentation function can be matched further onto a universal function defined in heavy-quark effective theory in order to factor off its residual dependence on the heavy-quark mass. By solving the evolution equation in the effective theory analytically, large logarithms of the ratio mu/mQ are resummed to all orders in perturbation theory. Connections with existing approaches to heavy-quark fragmentation are discussed. In particular, it is shown that previous attempts to extract logn(1-x) terms from the fragmentation function DQ/H(x,mQ) are incompatible with a proper separation of short- and long-distance effects.