Next-to-leading order QCD predictions for the signal of Dark Matter and photon associated production at the LHC

TL;DR

This paper presents NLO QCD predictions for dark matter signal detection via photon-associated production at the LHC, analyzing backgrounds and event characteristics to enhance discovery potential.

Contribution

It provides the first NLO QCD calculations for dark matter photon-associated production at the LHC, including background analysis and event distribution characteristics.

Findings

LHC can potentially discover the dark matter signal at 5σ with 1 fb⁻¹ at 7 TeV.

Background photon pT distributions decrease faster than the signal with increasing pT.

Signal events are concentrated in the central ηγ region, aiding event selection.

Abstract

We study the potential of LHC to discovery the signal of Dark Matter with photon associated production induced by a dimension six effective operator, including NLO QCD corrections. We investigate the main backgrounds from SM, i.e. $Z$ boson and a photon associated production with invisible dacay of $Z$ boson, and $Z$ boson and a jet production with the jet misidentified as a photon. We find that the $p_T^{\gamma}$ distributions of the backgrounds decrease faster than that of the signal with increasing of the transverse momentum of the photon. The $\eta^{\gamma}$ distributions of the backgrounds are almost flat in the full range of $\eta^{\gamma}$. In contrast, the signal lies mainly in the central region of $\eta^{\gamma}$. These characteristics may help to select the events in experiments. We show that in the parameter space allowed by the relic abundance constraint, which we have calculated at the NLO QCD level, the LHC with $\sqrt{S}=7{\rm TeV}$ may discovery this signal at the $5\sigma$ level after collecting an integrated luminosity of $1 {\rm fb}^{-1}$. On the other hand, if this signal is not observed at the LHC, we can set a lower limit on the new physics scale at the $3\sigma$ level.