NLO predictions for the production of a spin-two particle at the LHC

Goutam Das,Céline Degrande,Valentin Hirschi,Fabio Maltoni,Hua-Sheng Shao

doi:10.1016/j.physletb.2017.05.007

Abstract

We obtain predictions accurate at the next-to-leading order in QCD for the production of a generic spin-two particle in the most relevant channels at the LHC: production in association with coloured particles (inclusive, one jet, two jets and tt¯), with vector bosons (Z,W±,γ) and with the Higgs boson. We present total and differential cross sections as well as branching ratios as a function of the mass and the collision energy also considering the case of non-universal couplings to standard model particles. We find that the next-to-leading order corrections give rise to sizeable K factors for many channels, in some cases exposing the unitarity-violating behaviour of non-universal couplings scenarios, and in general greatly reduce the theoretical uncertainties. Our predictions are publicly available in the MadGraph5_aMC@NLO framework and can, therefore, be directly used in experimental simulations of spin-two particle production for arbitrary values of the mass and couplings.

Highlights

After the discovery of the 125 GeV Higgs boson at the LHC [1, 2], the main task of Run II is to explore higher energy scales searching for physics beyond the Standard Model (SM)
April 12, 2017 time a complete implementation of the Lagrangian of a generic spin-two particle so that all the relevant production channels for the LHC can be accurately simulated at Next-to-Leading Order (NLO) in QCD
Accurate predictions and in particular event generators at least at NLO in QCD and matched to Parton Showers (PS) are necessary to obtain simulations that can directly be used by the experimental collaborations to allow information to be efficiently extracted from experimental data

Summary

Introduction

After the discovery of the 125 GeV Higgs boson at the LHC [1, 2], the main task of Run II is to explore higher energy scales searching for physics beyond the Standard Model (SM). April 12, 2017 time a complete implementation of the Lagrangian of a generic spin-two particle so that all the relevant production channels for the LHC can be accurately simulated at Next-to-Leading Order (NLO) in QCD. In this context, accurate predictions and in particular event generators at least at NLO in QCD and matched to Parton Showers (PS) are necessary to obtain simulations that can directly be used by the experimental collaborations to allow information to be efficiently extracted from experimental data. For non-universal couplings, the spin-two current is not conserved and specific renormalisation constants need to be introduced to cancel left-over ultraviolet divergences [5]. The MC@NLO formalism [34] is employed to perform the matching between fixed-order NLO calculations and PS, making event generation possible

Production at LHC

Partial decay widths

Conclusions