Measurement of the exclusive gamma production cross-section in pp collisions at root s=7 TeV and 8 TeV

A study is presented of central exclusive production of gamma(n S) states, where the gamma (n S) resonances decay to the mu(+) mu(-) final state, using p p collision data recorded by the LHCb experiment. The cross-section is measured in the rapidity range 2 < y (gamma) < 4.5 where the muons are reconstructed in the pseudorapidity range 2 < eta (mu(+/-)) < 4.5. The data sample corresponds to an integrated luminosity of 2.9 fb(-1) and was collected at centreof- mass energies of 7TeV and 8TeV. The measured gamma(1 S) and gamma(2 S) production crosssections are sigma(pp -> p gamma(1S)p) = 9.0 +/- 1.7 pb and sigma(pp -> p gamma(2S)p) = 1.3 +/- 0.3 pb, where the first uncertainties are statistical and the second are systematic. The gamma (1S) cross-section is also measured as a function of rapidity and is found to be in good agreement with Standard Model predictions. An upper limit is set at 3.4 pb at the 95% confidence level for the exclusive gamma(3 S) production cross-section, including possible contamination from chi b (3P) -> gamma (3S)gamma decays.

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https://infoscience.epfl.ch/record/214168?ln=fr

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Luminosité

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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

Luminosité solaire

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Search for Higgs boson pair production in events with two bottom quarks and two tau leptons in proton–proton collisions at $\sqrt s$ =13TeV

Muhammad Ahmad, Benjamin William Allen, Georgios Anagnostou, Konstantin Androsov, Tagir Aushev, Michele Bianco, Roberto Castello, Yixing Chen, Xin Chen, Tian Cheng, Davide Cieri, Giuseppe Codispoti, Pratyush Das, Alessandro Degano, Milos Dordevic, Dipanwita Dutta, Matthias Finger, Francesco Fiori, Daniel Gonzalez, Seungkyu Ha, Csaba Hajdu, Peter Hansen, Ali Harb, Alexis Kalogeropoulos, Viktor Khristenko, Ji Hyun Kim, Donghyun Kim, Vineet Kumar, Sanjeev Kumar, Ajay Kumar, Ekaterina Kuznetsova, Wei Li, Ho Ling Li, Zhen Liu, Hao Liu, Shuai Liu, Werner Lustermann, Bibhuprasad Mahakud, Maren Tabea Meinhard, Amr Mohamed, Thomas Muller, Ioannis Papadopoulos, Vladimir Petrov, Quentin Python, Andrea Rizzi, Paolo Ronchese, Varun Sharma, Ashish Sharma, Lesya Shchutska, Muhammad Shoaib, Gurpreet Singh, Jan Steggemann, Xin Sun, Marco Trovato, Andromachi Tsirou, David Vannerom, Joao Varela, Yi Wang, Qian Wang, Zheng Wang, Jian Wang, Mingkui Wang, Hui Wang, Siyuan Wang, Muhammad Waqas, Matthias Weber, Matthias Wolf, Fan Xia, Meng Xiao, Zhirui Xu, Yong Yang, Kai Yi

A search for the production of Higgs boson pairs in proton–proton collisions at a centre-of-mass energy of 13 TeV is presented, using a data sample corresponding to an integrated luminosity of 35.9 fb−1 collected with the CMS detector at the LHC. Events with one Higgs boson decaying into two bottom quarks and the other decaying into two τ leptons are explored to investigate both resonant and nonresonant production mechanisms. The data are found to be consistent, within uncertainties, with the standard model background predictions. For resonant production, upper limits at the 95% confidence level are set on the production cross section for Higgs boson pairs as a function of the hypothesized resonance mass and are interpreted in the context of the minimal supersymmetric standard model. For nonresonant production, upper limits on the production cross section constrain the parameter space for anomalous Higgs boson couplings. The observed (expected) upper limit at 95% confidence level corresponds to about 30 (25) times the prediction of the standard model.

2018

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Measurement of CP violation and the B-s(0) meson decay width difference with B-s(0) -> J/psi K+K- and B-s(0) -> J/psi pi(+) pi(-)decays

Vladislav Balagura, 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, Ilya Komarov, Yiming Li, Johan Luisier, Maurizio Martinelli, Raluca Anca Muresan, Bastien Luca Muster, Tatsuya Nakada, Matthew Needham, Niko Neufeld, Cédric Potterat, Jessica Prisciandaro, Albert Puig Navarro, 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

The time-dependent CP asymmetry in B-s(0) -> J/psi K+ K- decays is measured using pp collision data at root s = 7 TeV, corresponding to an integrated luminosity of 1: 0 fb(-1), collected with the LHCb detector. The decay-time distribution is characterized by the decay widths Gamma(L) and Gamma(H) of the light and heavy mass eigenstates of the B-s(0) - (B) over barB(s)(0) system and by a CP-violating phase s. In a sample of 27 617 B-s(0) -> J/psi K+ K- decays, where the dominant contribution comes from B-s(0) -> J/psi K+ K- decays, these parameters are measured to be phi(s) = 0. 07 +/- 0.09(stat) +/- 0. 01(syst) rad, Gamma(s) equivalent to (Gamma(L) + Gamma(L))/2 = 0.663 +/- 0.005(stat) +/- 0.006(syst) ps(-1), and 0.006(syst) ps(-1), and Delta Gamma(s) equivalent to Gamma(L) - Gamma(L) = 0.100 +/- 0.016(stat) +/- 0.003(syst) ps(-1), corresponding to the single most precise determination of phi(s), Delta Gamma(s), and Gamma(s.). The result of performing a combined analysis with B-s(0) -> J/psi pi(+) pi(-) decays gives phi(s) = 0.01 +/- 0.07(stat) +/- 0.01(syst)rad, Gamma(s) = 0.661 +/- 0.004(stat) +/- 0.006(syst) ps(-1), and Delta Gamma(s) = 0.106 +/- 0.011(stat) +/- 0.007(syst) ps(-1). All measurements are in agreement with the Standard Model predictions.

Amer Physical Soc2013

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Measurement of the CKM angle gamma from a combination of B-+/- -> Dh(+/-) analyses

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, Vincent Fave, Christoph Frei, Guido Haefeli, Plamen Hristov Hopchev, Pierre Jaton, Anne Keune, Ilya Komarov, 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, Liang Sun, Frédéric Teubert, Mark Tobin, Minh Tâm Tran, Jian Wang, Jean Wicht, Songmei Wu, Yi Zhang, Lei Zhang

A combination of three LHCb measurements of the CKM angle gamma is presented. The decays B-+/- -> DK +/- and B-+/- -> D pi(+/-) are used, where D denotes an admixture of D-0 and (D) over bar (0) mesons, decaying into K+K-, pi(+)pi(-), K-+/-pi(-/+), K-+/-pi(-/+)pi(+/-)pi(-/+), or K-S(0)pi(+)pi(-) final states. All measurements use a dataset corresponding to 1.0 fb-1 of integrated luminosity. Combining results from B-+/- -> DK +/- Dill decays alone a best-fit value of gamma = 72.0 degrees is found, and confidence intervals are set gamma is an element of [56.4, 86.7]degrees at 68% CL, gamma is an element of [42.6, 99.6]degrees at 95% CL. The best-fit value of gamma found from a combination of results from B-+/- -> D pi(+/-) decays alone, is gamma = 18.9 degrees, and the confidence intervals gamma is an element of [7.4, 99.2]degrees boolean OR [167.9, 176.4]degrees at 68% CL are set, without constraint at 95% CL The combination of results from B1 DKI and B -> DTC decays gives a best-fit value of y = 72.6 degrees and the confidence intervals gamma is an element of [55.4, 82.3]degrees at 68% CL, gamma is an element of [40.2, 92.7]degrees at 95% CL are set. All values are expressed modulo 180 degrees, and are obtained taking into account the effect of D-0-(D) over bar (0) mixing. (C) 2013 CERN. Published by Elsevier B.V. All rights reserved.

Elsevier Science Bv2013

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