A search for the rare decays B(s)(0)mu+ mu- and B(0)mu+ mu- is performed with data collected in 2011 and 2012 with the LHCb experiment at the Large Hadron Collider. The data samples comprise 1.1fb(-1) of proton-proton collisions at sqrt[s]=8TeV and 1.0fb(-1) at sqrt[s]=7TeV. We observe an excess of B(s)(0)mu+ mu- 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(B(s)(0)mu+ mu-)=(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 B(0)mu+ mu- candidates is consistent with the background expectation, giving an upper limit of B(B(0)mu+ mu-)<9.4*10(-10) at 95% confidence level.

Aaij, R., Carboni, G., Santovetti, E., & Ii, (2013). First evidence for the decay B(s)(0)mu+ mu-. PHYSICAL REVIEW LETTERS, 110(2), 021801-021801 [10.1103/PhysRevLett.110.021801].

First evidence for the decay B(s)(0)mu+ mu-

CARBONI, GIOVANNI;SANTOVETTI, EMANUELE;
2013-09

Abstract

A search for the rare decays B(s)(0)mu+ mu- and B(0)mu+ mu- is performed with data collected in 2011 and 2012 with the LHCb experiment at the Large Hadron Collider. The data samples comprise 1.1fb(-1) of proton-proton collisions at sqrt[s]=8TeV and 1.0fb(-1) at sqrt[s]=7TeV. We observe an excess of B(s)(0)mu+ mu- 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(B(s)(0)mu+ mu-)=(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 B(0)mu+ mu- candidates is consistent with the background expectation, giving an upper limit of B(B(0)mu+ mu-)<9.4*10(-10) at 95% confidence level.
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore FIS/04 - Fisica Nucleare e Subnucleare
English
Aaij, R., Carboni, G., Santovetti, E., & Ii, (2013). First evidence for the decay B(s)(0)mu+ mu-. PHYSICAL REVIEW LETTERS, 110(2), 021801-021801 [10.1103/PhysRevLett.110.021801].
Aaij, R; Carboni, G; Santovetti, E; Ii,
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2108/134910
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