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W b bbar production in POWHEG

Carlo Oleari, Laura Reina

TL;DR

Addresses the need for a precise NLO+PS description of Wb bbar production, a key background to single-top and WH searches. Implements the NLO cross section in the POWHEG BOX framework and couples with PYTHIA and HERWIG to study showered predictions, including leptonic W decay correlations. Extensive validation against independent calculations confirms the correctness of the NLO implementation and the consistency of spin-correlation treatment. Results show large NLO corrections (K-factors up to ~3) and highlight the impact of heavy-quark mass and gluon-initiated channels on distributions, underscoring the importance of accurate W+heavy-jet backgrounds at the Tevatron and LHC.

Abstract

We present an implementation of the next-to-leading order hadronic production of a W boson in association with a pair of massive bottom quarks in the framework of POWHEG, a method to consistently interface NLO QCD calculations with shower Monte Carlo generators. The process has been implemented using the POWHEG BOX, an automated computer code that sistematically applies the POWHEG method to NLO QCD calculations. Spin correlations in the decay of the W boson into leptons have been taken into account using standard approximated techniques. We present phenomenological results for W b bbar-> l nu b bbar production, at both the Tevatron and the LHC, obtained by showering the POWHEG results with PYTHIA and HERWIG, and we discuss the outputs of the two different shower Monte Carlo programs.

W b bbar production in POWHEG

TL;DR

Addresses the need for a precise NLO+PS description of Wb bbar production, a key background to single-top and WH searches. Implements the NLO cross section in the POWHEG BOX framework and couples with PYTHIA and HERWIG to study showered predictions, including leptonic W decay correlations. Extensive validation against independent calculations confirms the correctness of the NLO implementation and the consistency of spin-correlation treatment. Results show large NLO corrections (K-factors up to ~3) and highlight the impact of heavy-quark mass and gluon-initiated channels on distributions, underscoring the importance of accurate W+heavy-jet backgrounds at the Tevatron and LHC.

Abstract

We present an implementation of the next-to-leading order hadronic production of a W boson in association with a pair of massive bottom quarks in the framework of POWHEG, a method to consistently interface NLO QCD calculations with shower Monte Carlo generators. The process has been implemented using the POWHEG BOX, an automated computer code that sistematically applies the POWHEG method to NLO QCD calculations. Spin correlations in the decay of the W boson into leptons have been taken into account using standard approximated techniques. We present phenomenological results for W b bbar-> l nu b bbar production, at both the Tevatron and the LHC, obtained by showering the POWHEG results with PYTHIA and HERWIG, and we discuss the outputs of the two different shower Monte Carlo programs.

Paper Structure

This paper contains 10 sections, 7 equations, 2 figures, 1 table.

Table of Contents

  1. Introduction
  2. Construction of the POWHEG implementation
  3. The next-to-leading order cross sections
  4. The POWHEG BOX ingredients
  5. Validation of the NLO code
  6. Theoretical introduction
  7. Generation of the underlying Born configuration
  8. Generation of the radiation variables
  9. Tuning of the real contribution
  10. $\boldsymbol{Wb\bar{b}}$ production

Figures (2)

  • Figure 1: The tree-level Feynman diagrams for $q\bar{q}^\prime\rightarrow Wb\bar{b}$.
  • Figure :