Search for the lepton-flavour violating decays B0 → K*0μ±e∓ and B s 0 $$ {B}_s^0 $$ → ϕμ±e∓

Abstract

Abstract

A search for the lepton-flavour violating decays B0 → K*0μ±e∓ and

B s 0

$$ {B}_s^0 $$ → ϕμ±e∓ is presented, using proton-proton collision data collected by the LHCb detector at the LHC, corresponding to an integrated luminosity of 9 fb−1. No significant signals are observed and upper limits of

B

B 0

→

K

∗ 0

μ +

e −

< 5.7 ×

10

− 9

6.9 ×

10

− 9

,

B

B 0

→

K

∗ 0

μ −

e +

< 6.8 ×

10

− 9

7.9 ×

10

− 9

,

B

B 0

→

K

∗ 0

μ ±

e ∓

< 10.1 ×

10

− 9

11.7 ×

10

− 9

,

B

B s 0

→ ϕ

μ ±

e ∓

< 16.0 ×

10

− 9

19.8 ×

10

− 9

$$ {\displaystyle \begin{array}{c}\mathcal{B}\left({B}^0\to {K}^{\ast 0}{\mu}^{+}{e}^{-}\right)<5.7\times {10}^{-9}\left(6.9\times {10}^{-9}\right),\\ {}\mathcal{B}\left({B}^0\to {K}^{\ast 0}{\mu}^{-}{e}^{+}\right)<6.8\times {10}^{-9}\left(7.9\times {10}^{-9}\right),\\ {}\mathcal{B}\left({B}^0\to {K}^{\ast 0}{\mu}^{\pm }{e}^{\mp}\right)<10.1\times {10}^{-9}\left(11.7\times {10}^{-9}\right),\\ {}\mathcal{B}\left({B}_s^0\to \phi {\mu}^{\pm }{e}^{\mp}\right)<16.0\times {10}^{-9}\left(19.8\times {10}^{-9}\right)\end{array}} $$

are set at 90% (95%) confidence level. These results constitute the world’s most stringent limits to date, with the limit on the decay

B s 0

$$ {B}_s^0 $$ → ϕμ±e∓ the first being set. In addition, limits are reported for scalar and left-handed lepton-flavour violating New Physics scenarios.