Search for heavy neutral leptons in $$W^+\rightarrow \mu ^{+}\mu ^{\pm }\, \text {jet}$$ W + → μ + μ ± jet decays

Abstract

Abstract A search is performed for heavy neutrinos in the decay of a W boson into two muons and a jet. The data set corresponds to an integrated luminosity of approximately

$$3.0\, \text {fb} ^{-1} $$

3.0

fb

- 1

of proton–proton collision data at centre-of-mass energies of 7 and

$$8\, \text {TeV} $$

8

TeV

collected with the LHCb experiment. Both same-sign and opposite-sign muons in the final state are considered. Data are found to be consistent with the expected background. Upper limits on the coupling of a heavy neutrino with the Standard Model neutrino are set at

$$95\%$$

95 %

confidence level in the heavy-neutrino mass range from 5 to

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

50

GeV/

c 2

. These are of the order of

$$10^{-3}$$

10

- 3

for lepton-number-conserving decays and of the order of

$$10^{-4}$$

10

- 4

for lepton-number-violating heavy-neutrino decays.