Resummation effects in the bottom-quark fragmentation function

TL;DR

This paper advances the theoretical understanding of bottom-quark fragmentation by combining fixed-order calculations with next-to-next-to-leading logarithmic resummation, providing precise perturbative fragmentation functions.

Contribution

It presents the first Mellin transform of the order-α_s^2 result for all fragmenting partons and includes gluon mixing in the evolution at NNLL accuracy.

Findings

Exact order-α_s^2 corrections included

Resummation achieved at NNLL accuracy

Perturbative fragmentation functions made available via LHAPDF

Abstract

We compute the perturbative component of the fragmentation function of the $b$ quark to the best of the present theoretical knowledge. The fixed-order calculation to order $\alpha_s^2$ of the fragmentation function at the initial scale is matched with soft-emission logarithm resummation to next-to-next-to-leading logarithmic accuracy, so that order-$\alpha_s^2$ corrections are accounted for exactly, and logarithmically enhanced contributions from loops of $b$ quarks are included. This requires the calculation of the Mellin transform of the order-$\alpha_s^2$ result in the whole complex plane for the Mellin variable, which we provide for the first time for all the fragmenting partons. Evolution is performed to next-to-next- to-leading log accuracy, and mixing with the gluon fragmentation function is taken into account. The perturbative fragmentation functions are made available via LHAPDF grids.