Diphoton signals in theories with large extra dimensions to NLO QCD at hadron colliders

M.C Kumar,Prakash Mathews,V Ravindran,Anurag Tripathi

doi:10.1016/j.physletb.2009.01.002

Abstract

We present a full next-to-leading order (NLO) QCD corrections to diphoton production at the hadron colliders in both standard model and ADD model. The invariant mass and rapidity distributions of the diphotons are obtained using a semi-analytical two cut-off phase space slicing method which allows for a successful numerical implementation of various kinematical cuts used in the experiments. The fragmentation photons are systematically removed using smooth-cone-isolation cuts on the photons. The NLO QCD corrections not only stabilise the perturbative predictions but also enhance the production cross section significantly.

Highlights

The gauge hierarchy problem has been one of the main motivations to go beyond the standard model (SM)
We present our results for invariant mass (Q) and rapidity (Y) distributions of the photon pair at large hadron collider (LHC)
We have employed the kinematical cuts given by ATLAS collaboration [16]: the transverse momentum pγT > 40 GeV for the harder photons, pγT > 25 GeV for the softer photon, and the rapidity |yγ| < 2.5 for each photon

Summary

Introduction

The gauge hierarchy problem has been one of the main motivations to go beyond the standard model (SM). In any typical scattering process at colliders, the gravity can enter through their KK propagator as well as through the real emission of KK states These KK states are large in number. The virtual effects of the KK modes could lead to the enhancement of the cross sections of pair productions in the processes like Drell-Yan, diphoton and dijet while the real emissions could lead to large missing ET signals giving some new observable like monojet, mono-photon in an experiment. We have systematically computed all the QCD effects to NLO in perturbation theory to various important observable in diphoton production that are sensitive to the ADD model. Quantitative estimates of QCD corrections to these observable are presented and our predictions are expected to be less sensitive to the factorisation scale

The Diphoton Production

Numerical Results

Conclusions