Improved limit on the branching fraction of the rare decay $${{K} ^0_{\mathrm { \scriptscriptstyle S}}} \rightarrow \mu ^+\mu ^-$$ K S 0 → μ + μ -

Author(s): Aaij, R; Adeva, B; Adinolfi, M; Ajaltouni, Z; Akar, S; Albrecht, J; Alessio, F; Alexander, M; Ali, S; Alkhazov, G; Alvarez Cartelle, P; Alves, AA; Amato, S; Amerio, S; Amhis, Y; An, L; Anderlini, L; Andreassi, G; Andreotti, M; Andrews, JE; Appleby, RB; Archilli, F; d’Argent, P; Arnau Romeu, J; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Baalouch, M; Babuschkin, I; Bachmann, S; Back, JJ; Badalov, A; Baesso, C; Baker, S; Balagura, V; Baldini, W; Baranov, A; Barlow, RJ; Barschel, C; Barsuk, S; Barter, W; Baryshnikov, F; Baszczyk, M; Batozskaya, V; Battista, V; Bay, A; Beaucourt, L; Beddow, J; Bedeschi, F; Bediaga, I; Beiter, A; Bel, LJ; Bellee, V; Belloli, N; Belous, K; Belyaev, I; Ben-Haim, E; Bencivenni, G; Benson, S; Beranek, S; Berezhnoy, A; Bernet, R; Bertolin, A; Betancourt, C; Betti, F; Bettler, MO; van Beuzekom, M; Bezshyiko, I; Bifani, S; Billoir, P; Birnkraut, A; Bitadze, A; Bizzeti, A; Blake, T; Blanc, F; Blouw, J; Blusk, S; Bocci, V; Boettcher, T; Bondar, A; Bondar, N; Bonivento, W; Bordyuzhin, I; Borgheresi, A | Abstract: © 2017, CERN for the benefit of the LHCb collaboration. A search for the decay KS0→μ+μ- is performed, based on a data sample of proton-proton collisions corresponding to an integrated luminosity of 3fb-1, collected by the LHCb experiment at centre-of-mass energies of 7 and 8TeV. The observed yield is consistent with the background-only hypothesis, yielding a limit on the branching fraction of B(KS0→μ+μ-)l0.8(1.0)×10-9 at 90%(95%) confidence level. This result improves the previous upper limit on the branching fraction by an order of magnitude.