HW/HZ + 0 and 1 jet at NLO with the POWHEG BOX interfaced to GoSam and their merging within MiNLO

TL;DR

This work presents HV and HV+1 jet generators within the POWHEG BOX framework, enhanced by a new GoSam interface that automates one-loop virtual corrections via the BLHA standard. By applying the MiNLO procedure to HV+1 jet production, the authors achieve NLO accuracy for both HV inclusive distributions and HV+1 jet observables, enabling a matched calculation with no explicit jet-matching scale. The study demonstrates good agreement between HV and HVJ-MiNLO across inclusive quantities while also enabling improved treatment of jet-related observables, and it outlines a viable route to NNLO+PS through reweighting HV to NNLO. This approach enhances precision for Higgs-related analyses in HV production channels and offers a scalable path for even higher-accuracy predictions in collider phenomenology.

Abstract

We present a generator for the production of a Higgs boson H in association with a vector boson V=W or Z (including subsequent V decay) plus zero and one jet, that can be used in conjunction with general-purpose shower Monte Carlo generators, according to the POWHEG method, as implemented within the POWHEG BOX framework. We have computed the virtual corrections using GoSam, a program for the automatic construction of virtual amplitudes. In order to do so, we have built a general interface of the POWHEG BOX to the GoSam package. With this addition, the construction of a POWHEG generator within the POWHEG BOX is now fully automatized, except for the construction of the Born phase space. Our HV + 1 jet generators can be run with the recently proposed MiNLO method for the choice of scales and the inclusion of Sudakov form factors. Since the HV production is very similar to V production, we were able to apply an improved MiNLO procedure, that was recently used in H and V production, also in the present case. This procedure is such that the resulting generator achieves NLO accuracy not only for inclusive distributions in HV + 1 jet production but also in HV production, i.e. when the associated jet is not resolved, yielding a further example of matched calculation with no matching scale.

Figures (14)

• Figure 1: A sample of leading-order Feynman diagrams for $HWj$ and $HZj$ production.
• Figure 6: NLO rapidity distributions of the $HZ$ pair (left plot) and of the $Z$ boson (right plot), in $HZj$ production. The red curves were obtained by using the full set of virtual diagrams, including the Feynman graphs containing a top-quark loop. The blue curves were computed neglecting the diagrams belonging to classes (\ref{['item:furry']}) and (\ref{['item:Yt']}).
• Figure 7: NLO transverse-momentum distributions of the $HZ$ pair (left plot) and of the $H$ boson (right plot), in $HZj$ production. The labels are as in fig. \ref{['fig:NLO_mass_y']}.
• Figure 8: Total cross section variation for HVJ- MiNLO (solid red) and HV (dashed black). The maximum and minimum values for the total cross section are taken from tabs. \ref{['tab:totHW']} and \ref{['tab:totHZ']}. The total cross section with central scales is drawn in dotted lines.
• Figure 9: Comparison between the HW+ PYTHIA result and the HWJ- MiNLO+ PYTHIA result for the $HW^-$ rapidity distribution at the LHC at 8 TeV. The left plot shows the 7-point scale-variation band for the HW generator, while the right plot shows the HWJ- MiNLO 7-point band.