Search for light long-lived particles decaying to displaced jets in proton-proton collisions at $\sqrt{s}$ = 13.6 TeV

TL;DR

This paper reports a search for light long-lived particles decaying into displaced jets at 13.6 TeV, using novel techniques to set new limits on Higgs decay branching fractions and constrain new physics models.

Contribution

Introduction of new trigger, reconstruction, and machine learning methods for detecting long-lived particles decaying to jets at the LHC.

Findings

No excess observed over background predictions.

Up to 10-fold improvement over previous limits for certain models.

First constraints on fraternal twin Higgs and folded supersymmetry models.

Abstract

A search for light long-lived particles decaying to displaced jets is presented, using a data sample of proton-proton collisions at a center-of-mass energy of 13.6 TeV, corresponding to an integrated luminosity of 34.7 fb$^{-1}$, collected with the CMS detector at the CERN LHC in 2022. Novel trigger, reconstruction, and machine-learning techniques were developed for and employed in this search. After all selections, the observations are consistent with the background predictions. Limits are presented on the branching fraction of the Higgs boson to long-lived particles that subsequently decay to quark pairs or tau lepton pairs. An improvement by up to a factor of 10 is achieved over previous limits for models with long-lived particle masses smaller than 60 GeV and proper decay lengths smaller than 1 m. The first constraints are placed on the fraternal twin Higgs and folded supersymmetry models, where the lower bounds on the top quark partner mass reach up to 350 GeV for the fraternal twin Higgs model and 250 GeV for the folded supersymmetry model.