Evidence for the Strangeness-Changing Weak Decay Xi(-)(b) -> Lambda(0)(b)pi(-)

Using a pp collision data sample corresponding to an integrated luminosity of 3.0 fb(-1), collected by the LHCb detector, we present the first search for the strangeness-changing weak decay Xi(-)(b) -> Delta(0)(b)pi(-). No b hadron decay of this type has been seen before. A signal for this decay, corresponding to a significance of 3.2 standard deviations, is reported. The relative rate is measured to be f Xi(-)(b)/f Lambda B-0(b)(Xi(-)(b) -> Lambda(0)(b)pi(-)) = (5.7 +/- 1.8(-0.9)(+0.8)) x 10(-4) where f Xi(-)(b) and f Lambda(0)(b) are the b -> Xi(-)(b) and b -> Lambda(0)(b) fragmentation fractions, and B(Xi(-)(b) -> Lambda(0)(b)pi(-)) is the branching fraction. Assuming f Xi(-)(b)/f Lambda(0)(b) is bounded between 0.1 and 0.3, the branching fraction B(Xi(-)(b) -> Lambda(0)(b)pi(-)) would lie in the range from (0.57 +/- 0.21)% to (0.19 +/- 0.07)%.

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https://infoscience.epfl.ch/record/216439?ln=fr

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

Vladislav Balagura, Aurelio Bay, Marc-Olivier Bettler, Frédéric Blanc, Joël Bressieux, Peter Clarke, Victor Coco, Greig Alan Cowan, Adam Davis, Michel De Cian, Hans Dijkstra, Frédéric Guillaume Dupertuis, Paolo Durante, Christoph Frei, Guido Haefeli, Pierre Jaton, Ilya Komarov, Yiming Li, Johan Luisier, Pietro Marino, Maurizio Martinelli, Andrei Martynov, Raluca Anca Muresan, Bastien Luca Muster, Tatsuya Nakada, Matthew Needham, Niko Neufeld, Luca Pescatore, Cédric Potterat, Jessica Prisciandaro, Barinjaka Rakotomiaramanana, Gerhard Raven, Julien Rouvinet, Olivier Schneider, Liang Sun, 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-0 -> mu(+)mu(-) is performed at the LHCb experiment. The data analyzed correspond to an integrated luminosity of 1 fb(-1) of pp collisions at a center-of-mass energy of 7 TeV and 2 fb(-1) at 8 TeV. An excess of B-s(0) -> mu(+)mu(-) signal candidates with respect to the background expectation is seen with a significance of 4.0 standard deviations. A time-integrated branching fraction of B(B-s(0) -> mu(+)mu(-)) = (2.9(-1.0)(+1.1)) x 10(-9) is obtained and an upper limit of B(B-0 -> mu(+)mu(-)) < 7.4 x 10(-10) at 95% confidence level is set. These results are consistent with the standard model expectations.

Amer Physical Soc2013

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Studies of beauty baryon decays to D(0)ph(-) and Lambda(+)(c)h(-) final states

Decays of beauty baryons to the D(0)ph(-) and Lambda(+)(c)h(-) final states (where h indicates a pion or a kaon) are studied using a data sample of pp collisions, corresponding to an integrated luminosity of 1.0 fb(-1), collected by the LHCb detector. The Cabibbo-suppressed decays Lambda(0)(b)-> D(0)pK(-) and Lambda(0)(b)->Lambda K-c(-) are observed, and their branching fractions are measured with respect to the decays Lambda(0)(b)-> D(0)p pi(-) and Lambda(0)(b)->Lambda(+)(c)pi(-). In addition, the first observation is reported of the decay of the neutral beauty-strange baryon Xi(0)(b) to the D(0)pK(-)final state, and a measurement of the Xi(0)(b) mass is performed. Evidence of the Xi(0)(b)->Lambda K-c(-) decay is also reported.

Amer Physical Soc2014

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Observations of Lambda(0)(b) -> Lambda K+pi(-) and Lambda(0)(b) -> Lambda K+K- decays and searches for other Lambda(0)(b) and Xi(0)(b) decays to Lambda h(+)h '(-) final states

Liupan An, Guido Andreassi, Aurelio Bay, Violaine Bellée, Federico Betti, Marc-Olivier Bettler, Frédéric Blanc, Maxim Borisyak, Peter Clarke, Victor Coco, Greig Alan Cowan, Adam Davis, Michel De Cian, Hans Dijkstra, Mirco Dorigo, Paolo Durante, Christoph Frei, Sebastiana Gianì, Olivier Göran Girard, Elena Graverini, Guido Haefeli, Xiaoxue Han, Thibaud Humair, Ilya Komarov, Axel Kuonen, Yiming Li, Alessandro Mapelli, Maurizio Martinelli, Bastien Luca Muster, Tatsuya Nakada, Matthew Needham, Niko Neufeld, Luca Pescatore, Cédric Potterat, Jessica Prisciandaro, Renato Quagliani, Gerhard Raven, Federico Leo Redi, Olivier Schneider, Maxime Schubiger, Liang Sun, Frédéric Teubert, Mark Tobin, Minh Tâm Tran, Jian Wang, Jean Wicht, Zhirui Xu, Hang Yin, Lei Zhang, Yi Zhang, Yu Zheng

A search is performed for the charmless three-body decays of the Lambda(0)(b) and Xi(0)(b) baryons to the final states Lambda h(+)h'(-), where h(') = pi or K. The analysis is based on a data sample, corresponding to an integrated luminosity of 3 fb-1 of pp collisions, collected by the LHCb experiment. The Lambda(0)(b) -> Lambda K+pi(-) and Lambda(0)(b) -> Lambda K+K- decays are observed for the first time and their branching fractions and CP asymmetry parameters are measured. Evidence is seen for the Lambda(0)(b) -> Lambda pi(+)pi(-) decay and limits are set on the branching fractions of Xi(0)(b) baryon decays to the Lambda h(+)h(-) final states.

Springer2016

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