Search for massive long-lived particles decaying semileptonically at $${\sqrt{s}}=13\,\hbox {TeV}$$ s = 13 TeV

Abstract

Abstract A search is performed for massive long-lived particles (LLPs) 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

$$\text {\,GeV\!/}c^2$$

\,GeV\!/

c 2

is produced by gluon fusion and decays into two LLPs. The analysis covers LLP mass values from 10

$$\text {\,GeV\!/}c^2$$

\,GeV\!/

c 2

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

$$\text {\,GeV\!/}c^2$$

\,GeV\!/

c 2

. The LLP lifetimes considered range from 5 to 200 ps. This study uses LHCb data collected from proton-proton collisions at

$$\sqrt{s} = 13\text {\,TeV} $$

s

= 13 \,TeV

, corresponding to an integrated luminosity of 5.4

$$\text {\,fb} ^{-1}$$

\,fb

- 1

. 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.