Abstract
We examine the capacity of the Large Hadron Collider to determine the mean proper lifetime of long-lived particles assuming different decay final states. We mostly concentrate on the high luminosity runs of the LHC, and therefore, develop our discussion in light of the high amount of pile-up and the various upgrades for the HL-LHC runs. We employ model-dependent and model-independent methods in order to reconstruct the proper lifetime of neutral long-lived particles decaying into displaced leptons, potentially accompanied by missing energy, as well as charged long-lived particles decaying ihnto leptons and missing energy. We also present a discussion for lifetime estimation of neutral long-lived particles decaying into displaced jets, along with the challenges in the high PU environment of HL-LHC. After a general discussion, we illustrate and discuss these methods using several new physics models. We conclude that the lifetime can indeed be reconstructed in many concrete cases. Finally, we discuss to which extent including timing information, which is an important addition in the Phase-II upgrade of CMS, can improve such an analysis.
Highlights
The lack of observation of new physics at the Large Hadron Collider (LHC) has prompted a re-evaluation of the strategies aiming to probe signals of physics beyond the standard model (BSM)
After some preliminary considerations related to existing limits on long-lived particles, experimental cuts, pile-up in the HL-LHC environment and some systematic uncertainties entering LLPrelated measurements, we studied whether the LLP lifetime can be reconstructed at the HL-LHC in four different scenarios: LLPs decaying into diplaced leptons, into displaced leptons accompanied by missing energy, a charged LLP decaying into a lepton along with missing energy and a neutral LLP decaying into displaced jets
In this work we studied the capacity of the high-luminosity LHC to reconstruct some key properties of long-lived particles, most notably their lifetime, in an optimistic scenario when such particles are observed
Summary
The lack of observation of new physics at the Large Hadron Collider (LHC) has prompted a re-evaluation of the strategies aiming to probe signals of physics beyond the standard model (BSM). In this paper we consider LLPs as states with a proper lifetime long enough such that they decay only after traversing some macroscopic distance (order of few cm) within the detector Such lifetimes can be induced either by rather small couplings or in specific kinematic configurations involving small mass splittings between the particles participating in the process or large propagator masses. We place ourselves in the hopeful scenario that long-lived particles (LLPs) will be observed at the High Luminosity runs of the Large Hadron Collider (HL-LHC) and we examine its capacity to reconstruct the LLP lifetime. We start this Section by reviewing some relations related to the lifetime of long-lived particles (LLPs)
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