First observation of the decay B-s(0) -> (KSK)-K-0*(892)(0) at LHCb

A search for B-(s)(0) -> K-S (0) K*(892)(0) decays is performed using pp collision data, corresponding to an integrated luminosity of 1.0 fb(-1), collected with the LHCb detector at a centre-of-mass energy of 7 TeV. The B-s (0) -> (KSK)-K-0*(892)(0) decay is observed for the first time, with a significance of 7.1 standard deviations. The branching fraction is measured to be B(B-s(0) -> (K) over bar K-0*(892)(0)) + B(B-s(0) -> K-0(K) over bar*(892)(0)) = (16.4 +/- 3.4 +/- 2.3) x10(-6), where the first uncertainty is statistical and the second is systematic. No evidence is found for the decay B-0 ->(KSK)-K-0*(892)(0) and an upper limit is set on the branching fraction, B(B-0 -> (K) over bar K-0*(892)(0)) + B(B-0 -> K-0(K) over bar*(892)(0)) < 0.96 x 10(-6) , at 90 % confidence level. All results are consistent with Standard Model predictions.

Study of the radiative penguin B0s [to] [phi] [gamma] and B0s [to] [gamma] [gamma] decays and the resonant B+ [to] K+ [gamma] [gamma] decays at Belle

Jean Wicht

We present the study of the radiative penguin Bs0 → ϕγ and Bs0 → γγ decays and the resonant B+ → K+h → K+γγ decays. We use data samples recorded at the Υ(4S) and Υ(5S) resonances with the Belle detector at KEKB, an electron-positron collider located in Tsukuba, Japan. The Υ(4S) sample corresponds to an integrated luminosity of 492 fb-1 and contains 535 million BB pairs. At the Υ(5S) resonance, we use a sample of 23.6 fb-1 containing 2.8 million Bs0 mesons. Penguin decays are loop-induced diagrams involving the heaviest particles of the Standard Model, the model describing, successfully so far, all particles and interactions, except the gravitation. Penguin decays are sensitive to physics beyond the Standard Model: particles foreseen by theories extending the Standard Model, whatever their masses are, can enter the loop and modify physics observables away from their Standard Model expectations. We report the first observation of a radiative penguin decay of the Bs0 meson in the Bs0 → ϕγ mode with a significance of 5.5 standard deviations. We measure Β(Bs0 → ϕγ) = (57 -15+18 (stat) -11+12 (syst)) × 10-6 in agreement with the expectation of the Standard Model. We do not observe any significant Bs0 → γγ signal and we compute an upper limit at the 90% confidence level on its branching fraction of Β(Bs0 → γγ) < 8.7 × 10-6. This limit is about six times more stringent than the previously published one. However, it is still about one order of magnitude larger than the expectation of the Standard Model and still above expectations of theories beyond the Standard Model. For the resonant B+ → K+h → K+γγ decays, we search for decays where the h particle can be a η, η', ηc, ηc(2S), χc0, χc2 or a J/ψ meson, or the X(3872) particle discovered in 2003 by the Belle collaboration. We observe the modes with h = η and η'. We obtain an evidence of the mode with h = ηc; this is the first time that a B+ → K+ηc signal is seen in the K+ γγ final state. We measure Β(B+ → K+η → K+γγ) = (0.87 -0.15+0.16 (stat) -0.07+0.10 (syst)) × 10-6, Β(B+ → K+η' → K+γγ) = (1.40 -0.15+0.16 (stat) -0.12+0.15 (syst)) × 10-6, Β(B+ → K+ηc → K+γγ) = (0.22 -0.07+0.09 (stat) -0.02+0.04 (syst)) × 10-6, with significances of 7.3, 13.8 and 4.1, respectively. For the other modes, we obtain limits on their branching fractions. We also measure or set limits on the branching fractions of the h → γγ decays for the modes where Β(B+ → K+h) has been measured elsewhere. We set for the first time an upper limit at the 90% confidence level on the branching fraction of the decay of the X(3872) particle into two photons of Β(X(3872) → γγ) < 1.1%.

EPFL2008

First Evidence for the Decay B-s(0) -> mu(+) mu(-)

Aurelio Bay, Marc-Olivier Bettler, Frédéric Blanc, Joël Bressieux, Peter Clarke, Victor Coco, Greig Alan Cowan, Michel De Cian, Hans Dijkstra, Frédéric Guillaume Dupertuis, Vincent Fave, Christoph Frei, Guido Haefeli, Plamen Hristov Hopchev, Pierre Jaton, Anne Keune, Yiming Li, Johan Luisier, Maurizio Martinelli, Raluca Anca Muresan, Bastien Luca Muster, Tatsuya Nakada, Matthew Needham, Niko Neufeld, Cédric Potterat, Jessica Prisciandaro, Barinjaka Rakotomiaramanana, Gerhard Raven, Julien Rouvinet, Christophe Salzmann, Olivier Schneider, Frédéric Teubert, Mark Tobin, Minh Tâm Tran, Jian Wang, Jean Wicht, Songmei Wu, Yi Zhang, Lei Zhang

A search for the rare decays B-s(0) -> mu(+) mu(-) and B-s(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 1.1 fb(-1) of proton-proton collisions at root s = 8 TeV and 1.0 fb(-1) at root s = 7 TeV. 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 x 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)) x 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-s(0) -> mu(+) mu-candidates is consistent with the background expectation, giving an upper limit of B(B-s(0) -> mu(+) mu(-)) < 9.4 x 10(-10) at 95% confidence level. DOI: 10.1103/PhysRevLett.110.021801

American Physical Society2013

Study of the radiative penguin B0s [to] [phi] [gamma] and B0s [to] [gamma] [gamma] decays and the resonant B+ [to] K+ [gamma] [gamma] decays at Belle

Jean Wicht

EPFL2008

First observation of the decay B-s(0) -> (KSK)-K-0*(892)(0) at LHCb

Measurement of the B-s(0) -> mu(+)mu(-) Branching Fraction and Search for B-0 -> mu(+)mu(-) Decays at the LHCb Experiment

Study of the radiative penguin B0s [to] [phi] [gamma] and B0s [to] [gamma] [gamma] decays and the resonant B+ [to] K+ [gamma] [gamma] decays at Belle

First Evidence for the Decay B-s(0) -> mu(+) mu(-)

Measurement of the B-s(0) -> mu(+)mu(-) Branching Fraction and Search for B-0 -> mu(+)mu(-) Decays at the LHCb Experiment

Study of the radiative penguin B0s [to] [phi] [gamma] and B0s [to] [gamma] [gamma] decays and the resonant B+ [to] K+ [gamma] [gamma] decays at Belle

First Evidence for the Decay B-s(0) -> mu(+) mu(-)