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Isospin Amplitudes in Lambda(0)(b) -> J/psi Lambda (Sigma(0)) and Xi(0)(b)-> J/psi Xi(0) (Lambda) Decays

Ratios of isospin amplitudes in hadron decays are a useful probe of the interplay between weak and strong interactions and allow searches for physics beyond the standard model. We present the first results on isospin amplitudes in b-baryon decays, using data corresponding to an integrated luminosity of 8.5 fb(-1), collected with the LHCb detector in pp collisions at center of mass energies of 7, 8, and 13 TeV. The isospin amplitude ratio vertical bar A(1) (Delta(0)(b) -> J/psi(Sigma(0)) /A(0) (Delta(0)(b) -> J/psi Lambda)vertical bar, where the subscript on A indicates the final-state isospin, is measured to be less than 1/21.8 at 95% confidence level. The Cabibbo suppressed Xi(0)(b) -> J/psi Lambda decay is observed for the first time, allowing for the measurement vertical bar A(0) (Xi(0)(b) -> J/psi Lambda) / A(1/2 )(Xi(0)(b) -> J/psi Xi(0))vertical bar = 0.37 +/- 0.06 +/- 0.02, where the uncertainties are statistical and systematic, respectively.

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Hossein Afsharnia, Liupan An, Guido Andreassi, Vladislav Balagura, Aurelio Bay, Violaine Bellée, Federico Betti, Marc-Olivier Bettler, Frédéric Blanc, Alexey Boldyrev, Maxim Borisyak, Sara Celani, Chunhui Chen, Peter Clarke, Victor Coco, Tommaso Colombo, Adam Davis, Michel De Cian, Hans Dijkstra, Mirco Dorigo, Paolo Durante, Dipanwita Dutta, Surapat Ek-In, François Fleuret, Christoph Frei, Olivier Göran Girard, Elena Graverini, Guido Haefeli, Xiaoxue Han, Plamen Hristov Hopchev, Thibaud Humair, Veronica Sølund Kirsebom, Almagul Kondybayeva, Xuan Li, Yiming Li, Ho Ling Li, Vladimir Macko, Pietro Marino, Maurizio Martinelli, Simone Meloni, Tatsuya Nakada, Tara Nanut, Matthew Needham, Niko Neufeld, Preema Rennee Pais, Luca Pescatore, Anton Petrov, Guillaume Max Pietrzyk, Renato Quagliani, Gerhard Raven, Federico Leo Redi, Olivier Schneider, Maxime Schubiger, Sebastian Schulte, Lesya Shchutska, Evgenii Shmanin, Pavol Stefko, Maria Elena Stramaglia, Liang Sun, Zhipeng Tang, Frédéric Teubert, Mark Tobin, Minh Tâm Tran, Carina Trippl, Mingkui Wang, Yi Wang, Zheng Wang, Jian Wang, Zhirui Xu, Hang Yin, Yi Zhang, Lei Zhang, Yu Zheng, Yao Zhou, Xiaoqing Zhou
AMER PHYSICAL SOC, 2020
Article

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https://infoscience.epfl.ch/record/276767?ln=fr

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Luminosité

En astronomie, la luminosité est la quantité totale d'énergie émise par unité de temps (le flux énergétique), par une étoile, une galaxie, ou n'importe quel autre objet céleste. Elle s'exprime en pr

LHCb

LHCb (Large Hadron Collider beauty experiment : Expérience du LHC sur le quark beauté) est une expérience de physique des particules utilisant les collisions de protons produites au collisionneur LHC

E=mc2

L'équation (lire « E égale m c carré » ou « E égale m c deux ») est une formule d'équivalence entre la masse et l'énergie, rendue célèbre par Albert Einstein dans une publication en 1905 sur la rela

Isospin amplitudes in $\Lambda_b^0\to J/\psi \Lambda(\Sigma^0)$ and $\Xi_b^0\to J/\psi \Xi^0(\Lambda)$ decays

Hossein Afsharnia, Liupan An, Guido Andreassi, Vladislav Balagura, Aurelio Bay, Violaine Bellée, Federico Betti, Marc-Olivier Bettler, Frédéric Blanc, Alexey Boldyrev, Maxim Borisyak, Daniel Hugo Cámpora Pérez, Sara Celani, Chunhui Chen, Peter Clarke, Victor Coco, Tommaso Colombo, Adam Davis, Michel De Cian, Hans Dijkstra, Mirco Dorigo, Paolo Durante, Dipanwita Dutta, Surapat Ek-In, Lino Ferreira Lopes, François Fleuret, Christoph Frei, Olivier Göran Girard, Luis Alberto Granado Cardoso, Elena Graverini, Guido Haefeli, Xiaoxue Han, Plamen Hristov Hopchev, Thibaud Humair, Veronica Sølund Kirsebom, Almagul Kondybayeva, Xuan Li, Ho Ling Li, Yiming Li, Yu Lu, Vladimir Macko, Pietro Marino, Maurizio Martinelli, Simone Meloni, Katharina Müller, Tatsuya Nakada, Tara Nanut, Matthew Needham, Niko Neufeld, Preema Rennee Pais, Luca Pescatore, Anton Petrov, Guillaume Max Pietrzyk, Sébastien Ponce, Albert Puig Navarro, Renato Quagliani, Gerhard Raven, Federico Leo Redi, Arnaud Robert, Olivier Schneider, Maxime Schubiger, Sebastian Schulte, Lesya Shchutska, Evgenii Shmanin, Pavol Stefko, Maria Elena Stramaglia, Liang Sun, Zhipeng Tang, Frédéric Teubert, Mark Tobin, Minh Tâm Tran, Carina Trippl, Maria Vieites Diaz, Zheng Wang, Mingkui Wang, Yi Wang, Jian Wang, Li Xu, Zhirui Xu, Hang Yin, Lei Zhang, Yi Zhang, Yu Zheng, Xiaoqing Zhou

Ratios of isospin amplitudes in hadron decays are a useful probe of the interplay between weak and strong interactions, and allow searches for physics beyond the Standard Model. We present the first results on isospin amplitudes in

b

-baryon decays, using data corresponding to an integrated luminosity of 8.5 fb

^{-1}

, collected with the LHCb detector in

pp

collisions at center of mass energies of 7, 8 and 13 TeV. The isospin amplitude ratio

|A_1(\Lambda_b^0\to J/\psi \Sigma^0)/A_0(\Lambda_b^0\to J/\psi\Lambda)|

, where the subscript on

A

indicates the final-state isospin, is measured to be less than

1/20.9

at 95% confidence level. The Cabibbo suppressed

\Xi_b^0\to J/\psi\Lambda

decay is observed for the first time, allowing for the measurement

|A_0(\Xi_b^0\to J/\psi\Lambda)/A_{1/2}(\Xi_b^0\to J/\psi\Xi^0)| =0.44 \pm 0.06\pm 0.02

, where the uncertainties are statistical and systematic, respectively.

2019

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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

Chargement

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

Liupan An, Guido Andreassi, Aurelio Bay, Violaine Bellée, 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, Chitsanu Khurewathanakul, Ilya Komarov, Axel Kuonen, Yiming Li, Alessandro Mapelli, Pietro Marino, 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, Maria Vieites Diaz, Jian Wang, Zhirui Xu, Yi Zhang, Lei Zhang

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)%.

Amer Physical Soc2015

Chargement

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