Inclusion of the QCD next-to-leading order corrections in the quark-gluon Monte Carlo shower

TL;DR

This paper develops a methodology to incorporate next-to-leading order QCD corrections into quark-gluon Monte Carlo showers, extending the accuracy of simulations for processes like electroweak boson production at the LHC.

Contribution

It introduces a new Monte Carlo factorization scheme that rigorously extends collinear factorization to the exclusive level and incorporates NLO corrections in the shower.

Findings

Constructed a leading order parton shower Monte Carlo from scratch.

Outlined a method to include NLO corrections in the hard process within the Monte Carlo.

Addressed the scheme difference between MC and MSbar, and demonstrated process universality.

Abstract

Methodology of including QCD NLO corrections in the quark--gluon Monte Carlo shower is outlined. The work concentrates on two issues: (i) constructing leading order (LO) parton shower Monte Carlo from scratch, such that it rigorously extends collinear factorization into the exclusive (fully unintegrated) one which we call the Monte Carlo factorization scheme; (ii) introducing next-to-leading-order (NLO) corrections to the hard process in this new environment. The presented solution is designed to be extended to the full NLO level Monte Carlo, including NLO corrections not only in the hard process but in the whole shower. The issue of the difference between the factorization scheme implemented in the Monte Carlo (MC) solution and the standard MSbar scheme is addressed. The principal MC implementation is designed for the electroweak boson production process at the LHC, but in order to discuss universality -- process independence, the deep inelastic lepton--hadron scaterring is also brought into the MC framework.