Search for the rare decay $${{{B} ^+}} \!\rightarrow {\mu ^+} {\mu ^-} {\mu ^+} {{\upnu } _\mu } $$ B + → μ + μ - μ + ν μ

Abstract

Abstract A search for the rare leptonic decay

$${{{B} ^+}} \!\rightarrow {\mu ^+} {\mu ^-} {\mu ^+} {{\upnu } _\mu } $$

B

+

→

μ +

μ -

μ +

ν μ

is performed using proton-proton collision data corresponding to an integrated luminosity of

$$4.7 \, {\hbox {fb}}^{-1}$$

4.7

fb

- 1

collected by the LHCb experiment. The search is carried out in the region where the lowest of the two

$${\mu ^+\mu ^-} $$

μ +

μ -

mass combinations is below

$$980 {\mathrm {\,MeV\!/}c^2} $$

980

MeV

/

c 2

. The data are consistent with the background-only hypothesis and an upper limit of

$$1.6 \times 10^{-8}$$

1.6 ×

10

- 8

at 95% confidence level is set on the branching fraction in the stated kinematic region.