# Search for the lepton-flavour-violating decays $B^0_s \rightarrow e^{\pm}\mu^{\mp}$ and {$B^0 \rightarrow e^{\pm} \mu^{\mp}$

Abstract : A search for the lepton-flavour violating decays \Bsemu and \Bdemu is performed with a data sample, corresponding to an integrated luminosity of \mbox{1.0} fb$^{-1}$ of $pp$ collisions at $\sqrt{s} = 7$\, TeV, collected by the LHCb experiment. The observed number of $B^0_s \to e^{\pm} \mu^{\mp}$ and $B^0 \to e^{\pm} \mu^{mp}$ candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be $BR(B^0_s \to e^{\pm} \mu^{\mp} < 1.1 \,(1.4) \times 10^{-8}$ and $BR (B^0 \to e^{\pm} \mu^{mp} < 2.8 \,(3.7) \times 10^{-9}$ at 90% (95%) confidence level (C.L.). These limits are a factor of twenty lower than those set by previous experiments. Lower bounds on the Pati-Salam leptoquark masses are also calculated, $M_{\rm LQ} (B^0_s \to e^{\pm} \mu^{mp}) > 107$} TeV/c$^2$ and $M_{\rm LQ} (B^0 \to e^{\pm} \mu^{\mp}) > 126$ TeV/c$^2$ at 95% C.L., and are a factor of two higher than the previous bounds.
Document type :
Journal articles

http://hal.in2p3.fr/in2p3-00846448
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Submitted on : Friday, July 19, 2013 - 10:48:26 AM
Last modification on : Thursday, December 16, 2021 - 2:10:29 PM

### Citation

R. Aaij, Y. Amhis, S. Barsuk, O. Callot, J. He, et al.. Search for the lepton-flavour-violating decays $B^0_s \rightarrow e^{\pm}\mu^{\mp}$ and {$B^0 \rightarrow e^{\pm} \mu^{\mp}$. Physical Review Letters, American Physical Society, 2013, 111, pp.141801. ⟨10.1103/PhysRevLett.111.141801⟩. ⟨in2p3-00846448⟩

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