B -hadron fragmentation functions at next-to-next-to-leading order from a global analysis of e+e− annihilation data

Maral Salajegheh,S Mohammad Moosavi Nejad,Bernd A Kniehl,Maryam Soleymaninia,Hamzeh Khanpour

doi:10.1103/physrevd.99.114001

Abstract

We present nonperturbative fragmentation functions (FFs) for bottom-flavored ($B$) hadrons both at next-to-leading (NLO) and, for the first time, at next-to-next-to-leading order (NNLO) in the $\overline{\mathrm{MS}}$ factorization scheme with five massless quark flavors. They are determined by fitting all available experimental data of inclusive single $B$-hadron production in $e^+e^-$ annihilation, from the ALEPH, DELPHI, and OPAL Collaborations at CERN LEP1 and the SLD Collaboration at SLAC SLC. The uncertainties in these FFs as well as in the corresponding observables are estimated using the Hessian approach. We perform comparisons with available NLO sets of $B$-hadron FFs. We apply our new FFs to generate theoretical predictions for the energy distribution of $B$ hadrons produced through the decay of unpolarized or polarized top quarks, to be measured at the CERN LHC.

Highlights

For a long time, there has been considerable interest in the study of bottom-flavored-hadron (B-hadron) production at hadron and eþe− colliders, both experimentally and theoretically
They are determined by fitting all available experimental data of inclusive single B-hadron production in eþe− annihilation, from the ALEPH, DELPHI, and OPAL collaborations at CERN LEP1 and the SLD collaboration at SLAC SLAC Linear Collider (SLC)
In the framework of the parton model of QCD, the description of the inclusive single production of identified hadrons h involves fragmentation functions (FFs), Dhaðx; Q2Þ. Their values correspond to the probability that the colored ppartffioffiffiffinffiffi a, which is produced at short distance, of order 1= Q2, fragments into the colorless hadron h carrying the fraction x of the energy of

Summary

INTRODUCTION

There has been considerable interest in the study of bottom-flavored-hadron (B-hadron) production at hadron and eþe− colliders, both experimentally and theoretically. In the case of eþe− annihilation, the hard-scattering cross sections for the inclusive production of parton a, to be convoluted with Dhaðx; Q2Þ, are known through NNLO [5,8,9,10,11]. This allows one to interpret eþe− data of the inclusive single production of hadron h at NNLO and to extract FFs at this order [12,13,14,15]. Owing to the factorization theorem, the FFs are independent of the process by which parton a is produced This allows one to transfer experimental information from eþe− annihilation to any other production mechanism, such as photoproduction, leptoproduction, hadroproduction, and two-photon scattering.

QCD FRAMEWORK FOR B-HADRON FFs

Nexp χ

RESULTS AND DISCUSSION

B-HADRON PRODUCTION BY TOP-QUARK DECAY

SUMMARY AND CONCLUSIONS