Determining the lifetime of long-lived particles at the HL-LHC

TL;DR

This paper evaluates the HL-LHC's ability to measure the lifetime of long-lived particles across various decay modes, considering high pile-up and detector upgrades, and explores methods to improve lifetime reconstruction accuracy.

Contribution

It introduces model-dependent and model-independent techniques for lifetime measurement of long-lived particles at HL-LHC, including the impact of timing information from upgrades.

Findings

Lifetime can be reconstructed in many cases.

Timing information improves lifetime measurement accuracy.

Challenges in high pile-up environments are addressed.

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.