Study of the $B_c^+ \to J/\psi D_s^+$ and $B_c^+ \to J/\psi D_s^{*+}$ decays with the ATLAS detector

G. Aad 1 Z. Barnovska 2 N. Berger 2 M. Delmastro 2 L. Di Ciaccio 2 T.K.O. Doan 2 S. Elles 2 C. Goy 2 T. Hryn’ova 2 S. Jézéquel 2 I. Koletsou 2 R. Lafaye 2 J. Leveque 2 N. Massol 2 G. Sauvage 2 E. Sauvan 2 O. Simard 2 T. Todorov 2 I. Wingerter-Seez 2 G . Rahal 3 M.K. Ayoub 4 A. Bassalat 4 C. Becot 4 S. Binet 4 C. Bourdarios 4 J.B. de Vivie De Regie 4 D. Delgove 4 L. Duflot 4 M. Escalier 4 L. Fayard 4 D. Fournier 4 E.L. Gkougkousis 4 J.-F. Grivaz 4 T. Guillemin 4 F. Hariri 4 S. Henrot-Versillé 4 J. Hrivnac 4 L. Iconomidou-Fayard 4 M. Kado 4 A. Lounis 4 N. Makovec 4 N. Morange 4 C. Nellist 4 L. Poggioli 4 P. Puzo 4 A. Renaud 4 D. Rousseau 4 G. Rybkin 4 A.C. Schaffer 4 E. Scifo 4 L. Serin 4 S. Simion 4 R. Tanaka 4 H.L. Tran 4 D. Zerwas 4 Zhongkai Zhang 4 Y. Zhao 4 D. Boumediene 5 Emmanuel Busato 5 D. Calvet 5 S. Calvet 5 J. Donini 5 E. Dubreuil 5 G. Gilles 5 Ph. Gris 5 H. Liao 5 R. Madar 5 D. Pallin 5 S.M. Romano Saez 5 C. Santoni 5 D. Simon 5 Timothée Theveneaux-Pelzer 5 F. Vazeille 5 S. Albrand 6 J. Brown 6 J. Collot 6 S. Crépé-Renaudin 6 P.A. Delsart 6 C. Gabaldon 6 M.H. Genest 6 J.Y. Hostachy 6 F. Ledroit-Guillon 6 A. Lleres 6 A. Lucotte 6 F. Malek 6 C. Monini 6 J. Stark 6 B. Trocmé 6 M. Wu 6 L. Alio 1 M. Barbero 1 Y. Coadou 1 C. Diaconu 1 S. Diglio 1 F. Djama 1 O. Duccu 1, 7 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
Abstract : The decays $B_c^+ \to J/\psi D_s^+$ and $B_c^+ \to J/\psi D_s^{*+}$ are studied with the ATLAS detector at the LHC using a dataset corresponding to integrated luminosities of 4.9 fb$^{-1}$ and 20.6 fb$^{-1}$ of $pp$ collisions collected at centre-of-mass energies $\sqrt{s} = 7$ TeV and 8 TeV, respectively. Signal candidates are identified through $J/\psi\to\mu^+\mu^-$ and $D_s^{(*)+}\to\phi\pi^+(\gamma/\pi^0)$ decays. With a two-dimensional likelihood fit involving the $B_c^+$ reconstructed invariant mass and an angle between the $\mu^+$ and $D_s^+$ candidate momenta in the muon pair rest frame, the yields of $B_c^+ \to J/\psi D_s^+$ and $B_c^+ \to J/\psi D_s^{*+}$, and the transverse polarisation fraction in $B_c^+ \to J/\psi D_s^{*+}$ decay are measured. The transverse polarisation fraction is determined to be $\Gamma_{\pm\pm}(B_c^+ \to J/\psi D_s^{*+})/\Gamma(B_c^+ \to J/\psi D_s^{*+}) = 0.38 \pm 0.23 \pm 0.07$, and the derived ratio of the branching fractions of the two modes is $\mathcal{B}_{B_c^+ \to J/\psi D_s^{*+}}/\mathcal{B}_{B_c^+ \to J/\psi D_s^+} = 2.8 \,^{+1.2}_{-0.8} \pm 0.3$, where the first error is statistical and the second is systematic. Finally, a sample of $B_c^+\to J/\psi\pi^+$ decays is used to derive the ratios of branching fractions $\mathcal{B}_{B_c^+ \to J/\psi D_s^+}/\mathcal{B}_{B_c^+ \to J/\psi \pi^+} = 3.8 \pm 1.1 \pm 0.4 \pm 0.2$ and $\mathcal{B}_{B_c^+ \to J/\psi D_s^{*+}}/\mathcal{B}_{B_c^+ \to J/\psi \pi^+} = 10.4 \pm 3.1 \pm 1.5 \pm 0.6$, where the third error corresponds to the uncertainty of the branching fraction of $D_s^+\to\phi(K^+K^-)\pi^+$ decay. The available theoretical predictions are generally consistent with the measurement.
Type de document :
Article dans une revue
European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2016, 76, pp.4. 〈10.1140/epjc/s10052-015-3743-8〉
Liste complète des métadonnées

http://hal.in2p3.fr/in2p3-01180723
Contributeur : Claudine Bombar <>
Soumis le : mardi 28 juillet 2015 - 09:34:23
Dernière modification le : mardi 22 mai 2018 - 21:48:09

Lien texte intégral

Identifiants

Citation

G. Aad, Z. Barnovska, N. Berger, M. Delmastro, L. Di Ciaccio, et al.. Study of the $B_c^+ \to J/\psi D_s^+$ and $B_c^+ \to J/\psi D_s^{*+}$ decays with the ATLAS detector. European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2016, 76, pp.4. 〈10.1140/epjc/s10052-015-3743-8〉. 〈in2p3-01180723〉

Partager

Métriques

Consultations de la notice

225