Exotic quarkonium states in CMS
1 Universitá degli Studi di Bari
2 INFN - Sezione di Bari
a e-mail: email@example.com
Published online: 22 March 2017
The studies of the production of the X(3872), either prompt or from B hadron decays, and of the J/ψϕ mass spectrum in B hadron decays have been carried out by using pp collisions at √s = 7 TeV collected with the CMS detector at the LHC. The cross-section ratio of the X(3872) with respect to the ψ(2S ) in the J/ψπ+π− decay channel and the fraction of X(3872) coming from B-hadron decays are measured as a function of transverse momentum (pT), covering unprecedentedly high values of pT. For the first time, the prompt production cross section for the X(3872) times the unknown branching fraction for the decay of X(3872) →J/ψπ+π− is extracted differentially in pT and compared to theoretical predictions based on the Non-Relativistic QCD (NRQCD) factorization approach. The dipion invariant-mass spectrum of the J/ψπ+π− system in the X(3872) decay is also investigated.
A peaking structure in the J/ψϕ mass spectrum near threshold is observed in B± → J/ψϕK± decays. The data sample, selected on the basis of the dimuon decay mode of the J/ψ, corresponds to an integrated luminosity of 5.2 fb−1. Fitting the structure to an S-wave relativistic Breit-Wigner lineshape above a three-body phase-space nonresonant component gives a signal statistical significance exceeding five standard deviations. The fitted mass and width values are m = 4148.0 ± 2.4(stat.) ± 6.3(syst.) MeV and Γ = 28−11+15 (stat.) ± 19(syst.) MeV, respectively. Evidence for an additional peaking structure at higher J/ψϕ mass is also reported.
The search for resonance-like structures in the Bs0π± invariant mass spectrum do not show any unexpected result. An upper limit on the relative production of the claimed X(5568) and Bs multiplied by the unknown branching fraction of the decay X(5568) → Bsπ± is estimated to be 3.9% at 95% CL in the most conservative case.
© The Authors, published by EDP Sciences, 2017
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