First evidence for the decay Bs0→μ+μ-

R. Aaij, C. Abellan Beteta, A. Adametz, B. Adeva, M. Adinolfi, C. Adrover, A. Affolder, Z. Ajaltouni, J. Albrecht, F. Alessio, M. Alexander, S. Ali, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves, S. Amato, Y. Amhis, L. Anderlini, J. Anderson, R. AndreassenR. B. Appleby, O. Aquines Gutierrez, F. Archilli, A. Artamonov, M. Artuso, E. Aslanides, G. Auriemma, S. Bachmann, J. J. Back, C. Baesso, W. Baldini, R. J. Barlow, C. Barschel, S. Barsuk, W. Barter, A. Bates, Th Bauer, A. Bay, J. Beddow, I. Bediaga, S. Belogurov, K. Belous, I. Belyaev, E. Ben-Haim, M. Benayoun, G. Bencivenni, S. Benson, J. Benton, A. Berezhnoy, R. Bernet, M. O. Bettler, M. Van Beuzekom, A. Bien, S. Bifani, T. Bird, A. Bizzeti, P. M. Bjørnstad, T. Blake, F. Blanc, C. Blanks, J. Blouw, S. Blusk, A. Bobrov, V. Bocci, A. Bondar, N. Bondar, W. Bonivento, S. Borghi, A. Borgia, T. J.V. Bowcock, E. Bowen, C. Bozzi, T. Brambach, J. Van Den Brand, J. Bressieux, D. Brett, M. Britsch, T. Britton, N. H. Brook, H. Brown, A. Büchler-Germann, I. Burducea, A. Bursche, J. Buytaert, S. Cadeddu, O. Callot, M. Calvi, M. Calvo Gomez, A. Camboni, P. Campana, A. Carbone, G. Carboni, R. Cardinale, A. Cardini, H. Carranza-Mejia

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Abstract

A search for the rare decays Bs0→μ+μ-and B0→μ+μ-is performed with data collected in 2011 and 2012 with the LHCb experiment at the Large Hadron Collider. The data samples comprise 1.1 fb-1 of proton-proton collisions at √s=8 TeV and 1.0 fb-1 at √s=7 TeV. We observe an excess of Bs0→μ+μ-candidates with respect to the background expectation. The probability that the background could produce such an excess or larger is 5.3×10-4 corresponding to a signal significance of 3.5 standard deviations. A maximum-likelihood fit gives a branching fraction of B(Bs0→μ+μ-)=(3.2-1.2+1.5) ×10-9, where the statistical uncertainty is 95% of the total uncertainty. This result is in agreement with the standard model expectation. The observed number of B0→μ+μ-candidates is consistent with the background expectation, giving an upper limit of B(B0→μ+μ-)<9.4×10-10 at 95% confidence level. © 2013 CERN. Published by the American Physical Society.
Original languageEnglish
JournalPhysical Review Letters
DOIs
Publication statusPublished - 7 Jan 2013
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

Aaij, R., Abellan Beteta, C., Adametz, A., Adeva, B., Adinolfi, M., Adrover, C., Affolder, A., Ajaltouni, Z., Albrecht, J., Alessio, F., Alexander, M., Ali, S., Alkhazov, G., Alvarez Cartelle, P., Alves, A. A., Amato, S., Amhis, Y., Anderlini, L., Anderson, J., ... Carranza-Mejia, H. (2013). First evidence for the decay Bs0→μ+μ-. Physical Review Letters. https://doi.org/10.1103/PhysRevLett.110.021801