Speaker
Description
We present a partonic cut-vertex analysis of multihadron fragmentation and dihadron fragmenting jet functions. The multihadron measurement is kept explicitly at the cut-vertex level, allowing the momentum-fraction dependence of the corresponding fragmentation functions to be derived from the factorized phase space rather than imposed by analogy with the single-hadron case. This provides a partonic origin of the number-density structure of multihadron fragmentation functions and shows that the additional hadron momentum fractions enter only through the nonperturbative measurement, leaving the perturbative splitting kernels universal. At next-to-leading order, the same formalism separates homogeneous contributions, which involve a single multihadron fragmentation function, from inhomogeneous contributions, which involve products of lower-multiplicity fragmentation functions. For the dihadron case, this reproduces the standard DiFF evolution. We further construct the dihadron fragmenting jet function and perform its one-loop matching onto DiFFs and products of single-hadron fragmentation functions. The finiteness of the matching coefficients demonstrates the necessity of treating the homogeneous and inhomogeneous channels as distinct convolution structures.
