Study of charmonium production in b-hadron decays and first evidence for the decay B-s(0) -> phi phi phi

Using decays to f-meson pairs, the inclusive production of charmonium states in b-hadron decays is studied with pp collision data corresponding to an integrated luminosity of 3.0 fb(-1), collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. Denoting by B-C = B(b -> CX) x B(C -> phi phi) the inclusive branching fraction of a b hadron to a charmonium state C that decays into a pair of phi mesons, ratios R-C2(C1) = B-C1/B-C2 are determined as R-eta c(1S)(chi c0) = 0.147 +/- 0.023 +/- 0.011, R-eta c(1S)(chi c1) = 0.073 +/- 0.016 +/- 0.006, R-eta c(1S)(chi c2) = 0.081 +/- 0.013 +/- 0.005, R-chi c0(chi c1) = 0.50 +/- 0.11 +/- 0.01, R-chi c0(chi c2) = 0.56 +/- 0.10 +/- 0.01 and R-eta c(1S)(eta c(2S)) = 0.040 +/- 0.011 +/- 0.004. Here and below the first uncertainties are statistical and the second systematic. Upper limits at 90% confidence level for the inclusive production of X(3872), X(3915) and.c2(2P) states are obtained as R-chi c1(X(3872)) < 0.34, R-chi c0(X(3915)) < 0.12 and R-chi c2(chi c2(2P)) < 0.16. Differential cross-sections as a function of transverse momentum are measured for the eta(c)(1S) and chi(c) states. The branching fraction of the decay B-s(0). phi phi phi is measured for the first time, B(B-s(0) -> phi phi phi) = (2.15 +/- 0.54 +/- 0.28 +/- 0.21 B) x10(-6). Here the third uncertainty is due to the branching fraction of the decay B-s(0) -> phi phi, which is used for normalization. No evidence for intermediate resonances is seen. A preferentially transverse phi polarization is observed. Themeasurements allow the determination of the ratio of the branching fractions for the eta(c)(1S) decays to ff and p (p) over bar as B(eta(c)(1S) -> phi phi)/B(eta(c)(1S) -> p (p) over bar) = 1.79 +/- 0.14 +/- 0.32.

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Liupan An, Guido Andreassi, Vladislav Balagura, Aurelio Bay, Violaine Bellée, Federico Betti, Marc-Olivier Bettler, Frédéric Blanc, Maxim Borisyak, Peter Clarke, Victor Coco, Greig Alan Cowan, Adam Davis, Hans Dijkstra, Mirco Dorigo, Paolo Durante, François Fleuret, Christoph Frei, Sebastiana Gianì, Olivier Göran Girard, Elena Graverini, Guido Haefeli, Xiaoxue Han, Plamen Hristov Hopchev, Thibaud Humair, Chitsanu Khurewathanakul, Ilya Komarov, Axel Kuonen, Yiming Li, Pietro Marino, Maurizio Martinelli, Katharina Müller, Tatsuya Nakada, Matthew Needham, Niko Neufeld, Preema Rennee Pais, Luca Pescatore, Anton Petrov, Cédric Potterat, Jessica Prisciandaro, Renato Quagliani, Gerhard Raven, Federico Leo Redi, Olivier Schneider, Maxime Schubiger, Pavol Stefko, Maria Elena Stramaglia, Liang Sun, Frédéric Teubert, Mark Tobin, Minh Tâm Tran, Jian Wang, Jean Wicht, Zhirui Xu, Hang Yin, Lei Zhang, Yi Zhang, Yu Zheng
Springer Nature, 2017
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Measurement of the eta(c)(1S) production cross-section in p p collisions at root s=13TeV

Hossein Afsharnia, Liupan An, Guido Andreassi, Vladislav Balagura, Aurelio Bay, Violaine Bellée, Federico Betti, Marc-Olivier Bettler, Frédéric Blanc, Alexey Boldyrev, Maxim Borisyak, Chunhui Chen, Peter Clarke, Victor Coco, Tommaso Colombo, Greig Alan Cowan, 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, Chitsanu Khurewathanakul, Veronica Sølund Kirsebom, Almagul Kondybayeva, Axel Kuonen, Xuan Li, Ho Ling Li, Yiming Li, 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, Renato Quagliani, Gerhard Raven, Federico Leo Redi, Olivier Schneider, Maxime Schubiger, Sebastian Schulte, Evgenii Shmanin, Pavol Stefko, Maria Elena Stramaglia, Liang Sun, Zhipeng Tang, Frédéric Teubert, Mark Tobin, Minh Tâm Tran, Zheng Wang, Mingkui Wang, Yi Wang, Jian Wang, Zhirui Xu, Hang Yin, Lei Zhang, Yi Zhang, Yu Zheng, Yao Zhou, Xiaoqing Zhou

Using a data sample corresponding to an integrated luminosity of 2.0 fb-1, collected by the LHCb experiment, the production of the.c(1S) state in proton-proton collisions at a centre-of-mass energy of v s = 13 TeVis studied in the rapidity range 2.0 < y < 4.5 and in the transverse momentum range 6.5 < pT < 14.0GeV. The cross-section for prompt production of.c(1S) mesons relative to that of the J/. meson is measured using the p p decay mode and is found to be s.c(1S)/sJ/. = 1.69 +/- 0.15 +/- 0.10 +/- 0.18. The quoted uncertainties are, in order, statistical, systematic and due to uncertainties on the branching fractions of the J/.. p p and.c. p p decays. The prompt.c(1S) production cross-section is determined to be s.c( 1S) = 1.26 +/- 0.11 +/- 0.08 +/- 0.14 mu b, where the last uncertainty includes that on the J/. meson cross-section. The ratio of the branching fractions of b-hadron decays to the.c(1S) and J/. states is measured to be Bb..c X /Bb. J/. X = 0.48 +/- 0.03 +/- 0.03 +/- 0.05, where the last uncertainty is due to those on the branching fractions of the J/.. p p and.c. p p decays. The difference between the J/. and.c(1S) masses is also determined to be 113.0 +/- 0.7 +/- 0.1MeV, which is the most precise single measurement of this quantity to date.

SPRINGER2020

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The First measurements of J/ψ production in proton-proton collisions at √s=13 TeV and study of the B→μμππ decays at LHCb

Ilya Komarov

We present a search for the B0s→π+π−μ+μ− and B0→π+π−μ+μ− decays using data collected by the LHCb detector in proton-proton collisions at centre-of-mass energies of 7 and 8TeV and corresponding to an integrated luminosity of 3 fb−1. We obtain the first observation of the B0s→π+π−μ+μ− decay with a statistical significance of 7.2σ and the first evidence of the B0→π+π−μ+μ− decay with a statistical significance of 4.8σ. The branching ratios of these decays are measured to beB(B0s→π+π−μ+μ−) = (8.6±1.5 (stat)±0.7 (syst)±0.7(norm))×10−8 and B(B0→π+π−μ+μ−) = (2.11±0.51 (stat)±0.15 (syst)±0.16(norm))×10−8, where the third uncertainty is due to the branching fraction of the decay B0→ J/ψ(→μ+μ−)K∗(892)0(→K+π−), used as a normalisation. We present also the first measurement of the production cross-section of J/ψ mesons in proton-proton collisions at centre-of-mass energy of 13TeV using the data collected by LHCb in 2015 and corresponding to an integrated luminosity of 3.02 ± 0.12 pb−1. The production cross-section is measured as a function of the transverse momentum pT and the rapidity y of the J/ψ meson in the region pT < 14GeV/c and 2.0 < y < 4.5, for both prompt J/ψ mesons and J/ψ mesons from b-hadron decays. The production cross-sections integrated over the kinematic coverage are found to be 15.30±0.03(stat)±0.86(syst)μb for prompt J/ψ and 2.34±0.01(stat)±0.13(syst)μb for J/ψ from b-hadron decays, assuming zero polarisation of the J/ψ meson. The ratios between these cross sections and the ones measured at the centre-of-mass-energy of 8TeV are also determined and compared with theoretical expectations. This measurement also validated a novel approach for online collection of ready-to-use data, which was implemented for the first time. The study of the performances of the Silicon Tracker of the LHCb experiment during the 2012 and 2015 years of operation is also reported, and my contribution to a novel monitoring system of this sub-detector is presented.

EPFL2016

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Updated branching fraction measurements of B-(s)(0) -> K(S)(0)h(+)h'(-) decays

Liupan An, Guido Andreassi, Vladislav Balagura, 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, François Fleuret, Christoph Frei, Sebastiana Gianì, Olivier Göran Girard, Elena Graverini, Guido Haefeli, Xiaoxue Han, Plamen Hristov Hopchev, Thibaud Humair, Chitsanu Khurewathanakul, Ilya Komarov, Axel Kuonen, Yiming Li, Pietro Marino, Maurizio Martinelli, Tatsuya Nakada, Matthew Needham, Niko Neufeld, Preema Rennee Pais, Luca Pescatore, Anton Petrov, Cédric Potterat, Jessica Prisciandaro, Renato Quagliani, Gerhard Raven, Federico Leo Redi, Olivier Schneider, Maxime Schubiger, Pavol Stefko, Maria Elena Stramaglia, Liang Sun, Frédéric Teubert, Mark Tobin, Minh Tâm Tran, Maria Vieites Diaz, Jian Wang, Jean Wicht, Zhirui Xu, Hang Yin, Lei Zhang, Yi Zhang, Yu Zheng

The charmless three-body decays B-(s)(0) -> K(S)(0)h(+)h '(-) (where h((')) - pi, K) are analysed using a sample of pp collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 3 fb(-1). The branching fractions are measured relative to that of the B-0 -> K-S(0) pi(+)pi(-) decay, and are determined to be: B(B-0 -> (KSK +/-)-K-0 pi(-/+))/B(B-0 -> K-S(0)pi(+)pi(-) = 0.123 +/- 0.009 (stat) +/- 0.015 (syst), B(B-0 -> (KSK+K-)-K-0)/B(B-0 -> K-S(0)pi(+)pi(-) = 0.549 +/- 0.018 (stat) +/- 0.033 (syst), B(B-S(0) -> K-S(0) pi(+)pi(-))/B(B-0 -> K-S(0)pi(+)pi(-)) = 0.191 +/- 0.027 (stat) +/- 0.031 (syst) +/- 0.011 (f(s)/f(d)), B(B-0 -> (KSK +/-)-K-0 pi(-/+))/B(B-0 -> K-S(0)pi(+)pi(-) = 1.70 +/- 0.07 (stat) +/- 0.11 (syst) +/- 0.10 (f(s)/f(d)), B(B-0 -> (KSK+K-)-K-0)/B(B-0 -> K-S(0)pi(+)pi(-) is an element of [0.008 - 0.051] at 90% confidence level, where f(s)/f(d) represents the ratio of hadronisation fractions of the B-s(0) and B-0 mesons.

Springer Science and Business Media LLC2017

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