Automated NLO calculations for asymmetric hadron-hadron collisions in MadGraph5_aMC@NLO

TL;DR

This paper extends MadGraph5_aMC@NLO to automate next-to-leading order calculations for asymmetric hadron-hadron collisions, enabling precise cross section predictions and uncertainty assessments for diverse nuclear reactions.

Contribution

The authors developed and validated a new module in MadGraph5_aMC@NLO for asymmetric collisions, broadening its applicability to proton-nucleus and nucleus-nucleus interactions at NLO.

Findings

Validated the code with W and Z boson production in pPb collisions.

Provided cross sections and nuclear modification factors for various particles in pPb collisions.

Demonstrated the framework's capability with multiple collision processes at the LHC.

Abstract

We have extended {\tt MadGraph5\_aMC@NLO} capabilities by implementing computations for asymmetric hadron-hadron collisions, including proton-nucleus, pion-hadron or nucleus-nucleus collisions in order to obtain a tool for automated perturbative computations of cross sections (or ratios of cross sections) in asymmetric reactions at next-to-leading (NLO) order in $\alpha_S$ in collinear factorisation. This tool, like the original symmetric version of \texttt{MadGraph5\_aMC@NLO}, automatically computes cross sections for different factorisation and renormalisation scales and PDFs provided by the {\tt LHAPDF} library, thereby allowing for an easy assessment of the associated theoretical uncertainties. In this paper, we present the validation of our code using $W$ and $Z$ boson production in $p$Pb collisions and Drell-Yan-pair production in $\pi W$ collisions. We also illustrate the capabilities of the framework by providing cross section and nuclear modification factors with their uncertainties for the production of $W$ and $Z$ bosons, charm and bottom quarks as well as associated production of $b\bar b+H^0$ in $p$Pb collisions at the LHC.