Next-to-leading order corrections to W+2 jet and Z+2 jet production at hadron colliders

TL;DR

This work delivers the first next-to-leading order QCD calculation of vector-boson production in association with two jets at hadron colliders, focusing on W+2 jets and Z/γ*+2 jets. Implemented in MCFM, the calculation uses dipole subtraction and the four-dimensional helicity scheme to produce fully differential, IR-finite predictions with leptonic decays. The results show significantly reduced scale dependence and notable shape changes in key distributions compared with LO, including the dijet-mass and jet-$p_T$ spectra, and provide predictions for the heavy-flavor content of jets in vector-boson events. These findings enhance the reliability of background estimates for Tevatron analyses and inform future LHC studies on multi-jet final states with vector bosons.

Abstract

We report on QCD radiative corrections to the processes p pbar --> W + 2 jets and p pbar --> Z + 2 jets at the Tevatron. These processes are included in the Monte Carlo program MCFM, which allows the calculation of any infra-red finite variable at next-to-leading order. Due to a better theoretical description of jets at next-to-leading order, some distributions exhibit significant corrections. As expected, the unphysical dependence of theoretical predictions upon the renormalization and factorization scales is greatly reduced compared to leading order. As an example of the predictions that may now be made with MCFM, we present a next-to-leading order estimate of the heavy flavor content of jets produced in association with vector bosons.

Figures (13)

• Figure 1: Sample diagrams for the process $\hbox{parton}+\hbox{parton} \to W/Z + 2~\hbox{partons}.$ As usual the vector boson is denoted by a wavy line.
• Figure 2: Color structure of the $W$+2 jet cross section vs. the dijet mass $M_{jj}$ at leading order. Proceeding from the top the five curves are, the total LO result, the two quark process at $O(N)$, the four quark process at $O(1)$, the four quark process at $O(1/N)$ and the two quark process at $O(1/N)$, where $N$ is the number of colors.
• Figure 3: Sample diagrams for the process $\hbox{parton}+\hbox{parton} \to W/Z + 3~\hbox{partons}$.
• Figure 4: The scale dependence of the $W$ and $Z$+1 jet predictions, with the factorization and renormalization scales equal and given by $\mu$. The differential distributions $d\sigma/dp_T$ are integrated over $15 < p_T < 200~{\rm GeV}$, with the basic cuts as described in section \ref{['cutsdesc']}.
• Figure 5: The scale dependence of the $W$ and $Z$+2 jet differential cross sections, $d\sigma/dM_{jj}$ integrated over $20 < M_{jj}<200$ GeV. For more details, see section \ref{['scaledep']}.