Abstract
We calculate, for the first time, the NNLO QCD corrections to identified heavy hadron production at hadron colliders. The calculation is based on a flexible numeric framework which allows the calculation of any distribution of a single identified heavy hadron plus jets and non-QCD particles. As a first application we provide NNLO QCD predictions for several differential distributions of B hadrons in t overline{t} events at the LHC. Among others, these predictions are needed for the precise determination of the top quark mass. The extension of our results to other processes, like open or associated B and charm production is straightforward. We also explore the prospects for extracting heavy flavor fragmentation functions from LHC data.
Highlights
When discussing the production of a heavy flavor of mass m at a hadron collider, it is instructive to distinguish two kinematic regimes: the low pT regime where pT ∼ m and the high pT one where pT m
Unlike the low pT case, a calculation of heavy flavor production at high pT is performed with a massless heavy quark since in the high-energy limit all terms that are power suppressed with m are negligible while the mass-independent terms as well as the logarithmically enhanced ones are automatically accounted for by the perturbative fragmentation function (PFF) formalism
Heavy flavor production at hadron colliders has traditionally demanded improved theoretical precision which matches the large statistics accumulated at colliders like the Tevatron and the LHC
Summary
A typical calculation in perturbative QCD involves final states with QCD partons, which are clustered into jets, and colourless particles such as leptons. The solution is to factorise the non-perturbative aspects into fragmentation functions [10] in analogy to how parton distribution functions are introduced to describe transitions from hadrons to partons in the initial state. As the above discussion indicates, the partonic cross section for producing a parton i is infrared unsafe and contains uncancelled divergences These are collinear divergences which factorise into lower-order contributions to the cross section and processindependent splitting functions. In practice a choice is made about the finite terms contained in these counterterms Such a choice implies that the IR renormalized coefficient and fragmentation functions, dσi and Di→h, are individually scheme dependent their convolution dσh is not, as one may expect from an observable. The solution of the DGLAP equation has the additional benefit that any large logarithms of the ratio of two scales are resummed with a logarithmic accuracy given by the order of the splitting functions used
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