Observation of ηc(2S)→pp¯ and search for X(3872)→pp¯ decays
R. Aaij
,
L. Beaucourt
(1)
,
M. Chefdeville
(1)
,
D. Decamp
(1)
,
N. Déléage
(1)
,
P. Ghez
(1)
,
J.-P. Lees
(1)
,
J.-F. Marchand
(1)
,
M.-N. Minard
(1)
,
B. Pietrzyk
(1)
,
S. t'Jampens
(1)
,
V. Tisserand
(1)
,
E. Tournefier
(1)
,
Z.J. Ajaltouni
(2)
,
M. Baalouch
(2)
,
E. Cogneras
(2)
,
O. Deschamps
(2)
,
G. Gazzoni
(2)
,
M. Grabalosa Gándara
(2)
,
C. Hadjivasiliou
(2)
,
P. Henrard
(2)
,
M. Kozeiha
(2)
,
R. Lefèvre
(2)
,
J. Maratas
(2)
,
S. Monteil
(2)
,
P. Perret
(2)
,
M. Vernet
(2)
,
S. Akar
(3)
,
J. Arnau Romeu
(3)
,
E. Aslanides
(3)
,
J. Cogan
(3)
,
K. De Bruyn
(3)
,
W. Kanso
(3)
,
R. Legac
(3)
,
O. Leroy
(3)
,
G. Mancinelli
(3)
,
M. Martin
(3)
,
A. Mordà
(3)
,
J. Serrano
(3)
,
A. Tayduganov
(3)
,
A. Tsaregorodtsev
(3)
R. Aaij
- Fonction : Auteur
M. Chefdeville
- Fonction : Auteur
- PersonId : 741874
- IdHAL : maximilien-chefdeville
- ORCID : 0000-0002-6553-6493
S. t'Jampens
- Fonction : Auteur
- PersonId : 736045
- IdHAL : stephane-tjampens
- ORCID : 0000-0003-4249-6641
E. Cogneras
- Fonction : Auteur
- PersonId : 743220
- IdHAL : eric-cogneras
- ORCID : 0000-0002-8933-9427
O. Deschamps
- Fonction : Auteur
- PersonId : 12089
- IdHAL : olivier-deschamps
- ORCID : 0000-0002-7047-6042
- IdRef : 161447368
P. Perret
- Fonction : Auteur
- PersonId : 739797
- IdHAL : pascal-perret
- ORCID : 0000-0002-5732-4343
M. Vernet
- Fonction : Auteur
- PersonId : 776331
- ORCID : 0000-0003-3128-0650
J. Cogan
- Fonction : Auteur
- PersonId : 750510
- IdHAL : julien-cogan
- ORCID : 0000-0001-7194-7566
- IdRef : 078779014
O. Leroy
- Fonction : Auteur
- PersonId : 171866
- IdHAL : olivier-leroy
- ORCID : 0000-0002-2589-240X
- IdRef : 169871835
J. Serrano
- Fonction : Auteur
- PersonId : 175327
- IdHAL : justine-serrano
- ORCID : 0000-0003-2489-7812
- IdRef : 127525521
Résumé
The first observation of the decay ηc(2S)→pp¯ is reported using proton-proton collision data corresponding to an integrated luminosity of 3.0fb−1 recorded by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The ηc(2S) resonance is produced in the decay B+→[cc¯]K+. The product of branching fractions normalised to that for the J/ψ intermediate state, Rηc(2S), is measured to be
Rηc(2S)≡B(B+→ηc(2S)K+)×B(ηc(2S)→pp¯)B(B+→J/ψK+)×B(J/ψ→pp¯)= (1.58±0.33±0.09)×10−2,
where the first uncertainty is statistical and the second systematic. No signals for the decays B+→X(3872)(→pp¯)K+ and B+→ψ(3770)(→pp¯)K+ are seen, and the 95\% confidence level upper limits on their relative branching ratios are % found to be RX(3872)<0.25×10−2 and Rψ(3770))<0.10. In addition, the mass differences between the ηc(1S) and the J/ψ states, between the ηc(2S) and the ψ(2S) states, and the natural width of the ηc(1S) are measured as
MJ/ψ−Mηc(1S)= 110.2±0.5±0.9MeV,Mψ(2S)−Mηc(2S)= 52.5±1.7±0.6MeV,Γηc(1S)= 34.0±1.9±1.3MeV.