The effect of real and virtual photons in the di-lepton channel at the LHC

TL;DR

This paper investigates the impact of real and virtual photon contributions to di-lepton production at the LHC, assessing their effects on background estimates and new physics searches, especially for high invariant mass regions.

Contribution

It provides a detailed analysis of photon-induced di-lepton production, including uncertainties and comparisons with the Drell-Yan process, highlighting their significance in new physics searches.

Findings

Photon contributions significantly affect di-lepton yields at TeV scales.

Uncertainties in photon-induced processes impact background estimations.

Photon effects are comparable to or exceed Drell-Yan in certain phase space regions.

Abstract

We present a study of di-lepton production at the CERN Large Hadron Collider with a particular focus on the contribution resulting from both real and virtual photons in the initial state. We discuss the region of phase space in which the invariant mass of the lepton pair is of the order of several TeV, where searches for new physics phenomena yielding a di-lepton signature are presently carried out. We study both the yield and associated uncertainties for all possible topologies in photon-induced di-lepton production and compare these with what is expected in the standard Drell-Yan channel, where quark-antiquark pairs are responsible for the production of lepton pairs. We analyse the impact of these QED contributions on the expected Standard Model background and on searches for new physics. In this latter case, we use the production of an extra heavy $Z^\prime$-boson predicted by the Sequential Standard Model (SSM) as a benchmark process.