Search for massive long-lived particles decaying semileptonically at sqrt(s)=13 TeV

TL;DR

This paper searches for long-lived particles decaying into a muon and two quarks at the LHCb experiment, setting upper limits on their production without observing any evidence of such particles.

Contribution

It introduces a search for long-lived particles decaying semileptonically, covering new mass and lifetime ranges, and provides the first limits for these specific models at 13 TeV.

Findings

No evidence of long-lived particles was found.

Upper limits on production cross-section times branching ratio were set.

The analysis extends previous searches to new mass and lifetime ranges.

Abstract

A search is performed for massive long-lived particles (LLP) decaying semileptonically into a muon and two quarks. Two kinds of LLP production processes were considered. In the first, a Higgs-like boson with mass from 30 to 200 GeV is produced by gluon fusion and decays into two LLPs. The analysis covers LLP mass values from 10 GeV up to about one half the Higgs-like boson mass. The second LLP production mode is directly from quark interactions, with LLP masses from 10 to 90 GeV. The LLP lifetimes considered range from 5 to 200 ps. This study uses LHCb data collected from proton-proton collisions at sqrt(s)=13 TeV, corresponding to an integrated luminosity of 5.4 1/fb. No evidence of these long-lived states has been observed, and upper limits on the production cross-section times branching ratio have been set for each model considered.