W gamma production in hadronic collisions using the POWHEG+MiNLO method

TL;DR

This paper presents a new NLO QCD calculation method for W gamma production in hadronic collisions, combining POWHEG and MiNLO techniques to achieve fully exclusive, accurate simulations that include photon fragmentation and are validated against LHC data.

Contribution

The paper introduces a novel approach combining POWHEG and MiNLO for NLO accurate, fully exclusive W gamma production simulations including photon fragmentation effects.

Findings

Good agreement with LHC 7 TeV data

Provides a publicly available simulation tool

Includes W leptonic decays and anomalous couplings

Abstract

We detail a calculation of W gamma production in hadronic collision, at Next-to-Leading Order (NLO) QCD interfaced to a shower generator according to the POWHEG prescription supplemented with the MiNLO procedure. The fixed order result is matched to an interleaved QCD+QED parton shower, in such a way that the contribution arising from hadron fragmentation into photons is fully modeled. In general, our calculation illustrates a new approach to the fully exclusive simulation of prompt photon production processes accurate at the NLO level in QCD. We compare our predictions to those of the NLO program MCFM, which treats the fragmentation contribution in terms of photon fragmentation functions. We also perform comparisons to available LHC data at 7 TeV, for which we observe good agreement, and provide phenomenological results for physics studies of the W gamma production process at the Run II of the LHC. The new tool, which includes W leptonic decays and the contribution of anomalous gauge couplings, allows a fully exclusive, hadron-level description of the W gamma process, and is publicly available at the repository of the POWHEG BOX. Our approach can be easily adapted to deal with other relevant isolated photon production processes in hadronic collisions.