Search for the Decays Bs0→τ+τ− and B0

Abstract

A search for the rare decays B_{s}^{0}→τ^{+}τ^{-} and B^{0}→τ^{+}τ^{-} is performed using proton-proton collision data collected with the LHCb detector. The data sample corresponds to an integrated luminosity of 3 fb^{-1} collected in 2011 and 2012. The τ leptons are reconstructed through the decay τ^{-}→π^{-}π^{+}π^{-}ν_{τ}. Assuming no contribution from B^{0}→τ^{+}τ^{-} decays, an upper limit is set on the branching fraction B(B_{s}^{0}→τ^{+}τ^{-})<6.8×10^{-3} at the 95% confidence level. If instead no contribution from B_{s}^{0}→τ^{+}τ^{-} decays is assumed, the limit is B(B^{0}→τ^{+}τ^{-})<2.1×10^{-3} at the 95% confidence level. These results correspond to the first direct limit on B(B_{s}^{0}→τ^{+}τ^{-}) and the world's best limit on B(B^{0}→τ^{+}τ^{-}).

FlavBit: a GAMBIT module for computing flavour observables and likelihoods

“…For B 0 s → μ + μ − , we adopt the latest result from LHCb [104], [109][110][111], which are currently much less constraining for models of new physics than the muon channels; we therefore do not include them in the FlavBit likelihood.…”

On the angular distribution of Λb → Λ(→ N π)τ +τ − decay

“…We note that so far no b → sτ + τ − transition has yet been observed. Only the LHCb has searched for B s → τ + τ − and provides an upper limit [21] …”

“…For phenomenological analysis, we study the Λ b → Λ(→ pπ)τ + τ − decay and present determinations of several observables in the SM and in the presence of the NP couplings. At present, no b → sτ + τ − transition has yet been observed and there are only upper limits on B s → τ + τ − and B + → K + τ + τ − from the LHCb [21] and BaBar [22], respectively. Interestingly, it has been shown in refs.…”

Rare decays and exotic states in quark flavour physics

“…However, experimental searches for these decays are complicated by the presence of at least two neutrinos in the final state due to the τ decays. Reconstructing the τ lepton in its hadronic final state τ − → π − π + π − ν τ , the LHCb collaboration has obtained the first limit on the B 0 s → τ + τ − branching ratio at 6.8 × 10 −3 (95% CL) and the best limit on B(B 0 d → τ + τ − ), at 2.1 × 10 −3 (95% CL) [8], using Run 1 data. These limits are orders of magnitudes higher than the SM predictions but open the perspective of other rare decays into τ leptons being studied at LHC experiments.…”