B-hadron production in NNLO QCD: application to LHC t$$ \overline{t} $$ events with leptonic decays

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$$ \overline{t} $$ 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.

Single Photon Production at Hadron Colliders at NNLO QCD with Realistic Photon Isolation

“…Up to now, next-to-next-to-leading order (NNLO) calculations [44][45][46] of isolated photon and photon-plus-jet production were only performed for a dynamical cone isolation (or a hybrid variant thereof [47]), since none of the available infrared subtraction schemes was able to handle fragmentation processes at NNLO. This conceptual limitation has been overcome recently with the incorporation of heavy hadron fragmentation processes into residue subtraction [48] and photon fragmentation processes in antenna subtraction [49]. In this work, we employ the antenna subtraction method [50][51][52] to compute the NNLO corrections to isolated photon and photon-plus-jet observables.…”

Selected Results in Heavy Quark Fragmentation

“…[6,7] are quite inclusive and limited to the prediction of the x B distributions, as discussed in the introduction, Refs. [23,24] provide a Monte Carlo code for top production and decay, in such a way that one is able to study other observables. At the moment, Ref.…”

“…Beyond NLO+NLL, Ref. [23] describes, in the top-quark narrow-width approximation, t t production and bottom fragmentation in top decays at NNLO in the framework of perturbative fragmentation functions, with NNLL DGLAP evolution and NNLL threshold resummation in the initial condition, with no large-x resummation in the top-to-bottom coefficient function.…”

“…[22] fits a hadronization model with two free parameters [32] to LEP and SLD data either altogether or discarding the OPAL ones. This model, along with its best-fit parameters, was then implemented in the Monte Carlo code developed in [23] to describe t t production and decay at NNLO. In the following part of this section, I wish to review the alternative method based on an effective strong coupling constant, proposed in [16] and employed in Refs.…”

Event Generators for High-Energy Physics Experiments

“…The production of charm quarks can be evaluated at NLO in the QCD expansion, either at fixed-order in the three-flavor-number scheme (3FNS) or in a general-mass variable-flavor-number scheme (GM-VFN) [1236,1237] such as FONLL or ACOT which accounts for potentially large mass logarithms in the collinear limit. Recently, the NNLO calculation for B-meson production at the LHC has been presented [1238], though its applicability to the charm case requires further work. Given that charm production in the forward region is sensitive to the small-x region down to x 10 −7 for the FPF acceptance, accurate calculations may require accounting for BFKL small-x resummation effects [1239], already relevant for the HERA kinematics [1240,1241], or for eventual non-linear QCD dynamics such as those describing gluon saturation.…”