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 - Université Clermont Auvergne Accéder directement au contenu
Article Dans Une Revue Physics Letters B Année : 2015

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) , Sara 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)
G. Aad
D. Rousseau
N. Berger
T. Hryn’ova
Y. Coadou
S. Calvet

Résumé

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.

Dates et versions

in2p3-01181351 , version 1 (30-07-2015)

Identifiants

Citer

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, 2015, 751, pp.63-80. ⟨10.1016/j.physletb.2015.10.009⟩. ⟨in2p3-01181351⟩
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