Measurement of the branching ratio $\Gamma(\Lambda_b^0 \rightarrow \psi(2S)\Lambda^0)/\Gamma(\Lambda_b^0 \rightarrow J/\psi\Lambda^0)$ with the ATLAS detector

G. Aad 1 M.K. Ayoub 2 A. Bassalat 2 C. Becot 2 S. Binet 2 C. Bourdarios 2 J.B. de Vivie De Regie 2 D. Delgove 2 L. Duflot 2 M. Escalier 2 L. Fayard 2 D. Fournier 2 E.L. Gkougkousis 2 J.-F. Grivaz 2 T. Guillemin 2 F. Hariri 2 S. Henrot-Versillé 2 J. Hrivnac 2 L. Iconomidou-Fayard 2 M. Kado 2 A. Lounis 2 N. Makovec 2 N. Morange 2 C. Nellist 2 L. Poggioli 2 P. Puzo 2 A. Renaud 2 D. Rousseau 2 G. Rybkin 2 A.C. Schaffer 2 E. Scifo 2 L. Serin 2 S. Simion 2 R. Tanaka 2 H.L. Tran 2 D. Zerwas 2 Zhongkai Zhang 2 Y. Zhao 2 G. Rahal 3 Z. Barnovska 4 N. Berger 4 M. Delmastro 4 L. Di Ciaccio 4 S. Elles 4 T. Hryn’ova 4 S. Jézéquel 4 I. Koletsou 4 R. Lafaye 4 J. Leveque 4 N. Massol 4 G. Sauvage 4 E. Sauvan 4 O. Simard 4 T. Todorov 4 I. Wingerter-Seez 4 S. Albrand 5 J. Brown 5 J. Collot 5 S. Crépé-Renaudin 5 P.A. Delsart 5 C. Gabaldon 5 M.H. Genest 5 J.Y. Hostachy 5 F. Ledroit-Guillon 5 A. Lleres 5 A. Lucotte 5 F. Malek 5 C. Monini 5 J. Stark 5 B. Trocmé 5 M. Wu 5 L. Alio 1 M. Barbero 1 Y. Coadou 1 C. Diaconu 1 S. Diglio 1 F. Djama 1 O. Duccu 1, 6 L. Feligioni 1 J. Gao 1 G.D. Hallewell 1 F. Hubaut 1 S.J. Kahn 1 E. B. F. G. Knoops 1 E. Le Guirriec 1 J. Liu 1 K. Liu 1 D. Madaffari 1 K. Mochizuki 1 E. Monnier 1 S. Muanza 1 Y. Nagai 1 E. Nagy 1 P. Pralavorio 1 A. Rozanov 1 T. Serre 1 M. Talby 1 R.E. Ticse Torres 1 E. Tiouchichine 1 S. Tisserant 1 J. Toth 1 F. Touchard 1 L. Vacavant 1 D. Boumediene 7 Emmanuel Busato 7 D. Calvet 7 S. Calvet 7 J. Donini 7 E. Dubreuil 7 G. Gilles 7 Ph. Gris 7 H. Liao 7 R. Madar 7 D. Pallin 7 S.M. Romano Saez 7 C. Santoni 7 D. Simon 7 Timothée Theveneaux-Pelzer 7 F. Vazeille 7 E. Yatsenko 4
Abstract : An observation of the $\Lambda_b^0 \rightarrow \psi(2S) \Lambda^0$ decay and a comparison of its branching fraction with that of the $\Lambda_b^0 \rightarrow J/\psi \Lambda^0$ decay has been made with the ATLAS detector in proton--proton collisions at $\sqrt{s}=8\,$TeV at the LHC using an integrated luminosity of $20.6\,$fb$^{-1}$. The $J/\psi$ and $\psi(2S)$ mesons are reconstructed in their decays to a muon pair, while the $\Lambda^0\rightarrow p\pi^-$ decay is exploited for the $\Lambda^0$ baryon reconstruction. The $\Lambda_b^0$ baryons are reconstructed with transverse momentum $p_{\rm T}>10\,$GeV and pseudorapidity $|\eta|<2.1$. The measured branching ratio of the $\Lambda_b^0 \rightarrow \psi(2S) \Lambda^0$ and $\Lambda_b^0 \rightarrow J/\psi \Lambda^0$ decays is $\Gamma(\Lambda_b^0 \rightarrow \psi(2S)\Lambda^0)/\Gamma(\Lambda_b^0 \rightarrow J/\psi\Lambda^0) = 0.501\pm 0.033 ({\rm stat})\pm 0.019({\rm syst})$, lower than the expectation from the covariant quark model.
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Physics Letters B, Elsevier, 2015, 751, pp.63-80. 〈10.1016/j.physletb.2015.10.009〉
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Soumis le : jeudi 30 juillet 2015 - 09:12:29
Dernière modification le : mercredi 16 mai 2018 - 15:10:07

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G. Aad, M.K. Ayoub, A. Bassalat, C. Becot, S. Binet, et al.. Measurement of the branching ratio $\Gamma(\Lambda_b^0 \rightarrow \psi(2S)\Lambda^0)/\Gamma(\Lambda_b^0 \rightarrow J/\psi\Lambda^0)$ with the ATLAS detector. Physics Letters B, Elsevier, 2015, 751, pp.63-80. 〈10.1016/j.physletb.2015.10.009〉. 〈in2p3-01181351〉

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