SUSY backgrounds to Standard Model calibration processes at the LHC

TL;DR

This paper investigates how low-mass supersymmetry could distort standard calibration processes at the LHC, potentially mimicking detector issues and highlighting the need for methods to identify new physics in calibration data.

Contribution

It demonstrates that low-mass SUSY particles can significantly alter SM calibration signals and proposes methods to detect these effects during early LHC data analysis.

Findings

SUSY can cause deviations in Z+jets and W+jets event distributions

SUSY may affect top quark invariant and transverse mass distributions

Calibration data can contain signatures of new physics, not just detector issues

Abstract

One of the first orders of business for LHC experiments after beam turn-on will be to calibrate the detectors using well understood Standard Model (SM) processes such as W and Z production and ttbar production. These familiar SM processes can be used to calibrate the electromagnetic and hadronic calorimeters, and also to calibrate the associated missing transverse energy signal. However, the presence of new physics may already affect the results coming from these standard benchmark processes. We show that the presence of relatively low mass supersymmetry (SUSY) particles may give rise to significant deviations from SM predictions of Z+jets and W+jets events for jet multiplicity $\ge 4$ or $\ge 5$, respectively. Furthermore, the presence of low mass SUSY may cause non-standard deviations to appear in top quark invariant and transverse mass distributions. Thus, effects that might be construed as detector mal-performance could in fact be the presence of new physics. We advocate several methods to check when new physics might be present within SM calibration data.