Search for long-lived particles decaying to $$e ^\pm $$ e ± $$\mu ^\mp $$ μ ∓ $$\nu $$ ν

Abstract

Abstract Long-lived particles decaying to

$${e ^\pm } {\mu ^\mp } {\nu } $$

e ±

μ ∓

ν

, with masses between 7 and

$$50 \,\text {GeV/}c^2 $$

50

GeV/

c 2

and lifetimes between 2 and

$$50 \,\text {ps} $$

50

ps

, are searched for by looking at displaced vertices containing electrons and muons of opposite charges. The search is performed using

$$5.4 \,\text {fb} ^{-1} $$

5.4

fb

- 1

of

$$p $$

p

$$p $$

p

collisions collected with the LHCb detector at a centre-of-mass energy of

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

s

= 13

TeV

. Three mechanisms of production of long-lived particles are considered: the direct pair production from quark interactions, the pair production from the decay of a Standard-Model-like Higgs boson with a mass of

$$125 \,\text {GeV/}c^2 $$

125

GeV/

c 2

, and the charged current production from an on-shell

$$W $$

W

boson with an additional lepton. No evidence of these long-lived states is obtained and upper limits on the production cross-section times branching fraction are set on the different production modes.