  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.
