Search for the Bs0→ μ⁺μ⁻γ decay

Abstract

Abstract A search for the fully reconstructed $$ {B}_s^0 $$ B s 0

→ μ+μ−γ decay is performed at the LHCb experiment using proton-proton collisions at $$ \sqrt{s} $$

s

= 13 TeV corresponding to an integrated luminosity of 5.4 fb−1. No significant signal is found and upper limits on the branching fraction in intervals of the dimuon mass are set$$ {\displaystyle \begin{array}{cc}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu}^{+}{\mu}^{-}\right)\in \left[2{m}_{\mu },1.70\right]\textrm{GeV}/{c}^2,\\ {}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<7.7\times {10}^{-8},&\ m\left({\mu}^{+}{\mu}^{-}\right)\in \left[\textrm{1.70,2.88}\right]\textrm{GeV}/{c}^2,\\ {}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu}^{+}{\mu}^{-}\right)\in \left[3.92,{m}_{B_s^0}\right]\textrm{GeV}/{c}^2,\end{array}} $$

B

B s 0

→

μ +

μ −

γ

< 4.2 ×

10

− 8

,

m

μ +

μ −

∈

2

m μ

1.70

GeV /

c 2

,

B

B s 0

→

μ +

μ −

γ

< 7.7 ×

10

− 8

,

m

μ +

μ −

∈

1.70, 2.88

GeV /

c 2

,

B

B s 0

→

μ +

μ −

γ

< 4.2 ×

10

− 8

,

m

μ +

μ −

∈

3.92

m

B s 0

GeV /

c 2

,

at 95% confidence level. Additionally, upper limits are set on the branching fraction in the [2mμ, 1.70] GeV/c2 dimuon mass region excluding the contribution from the intermediate ϕ(1020) meson, and in the region combining all dimuon-mass intervals.