1,167 research outputs found

    Evidence of ΄(1S)→J/ψ+χc1\Upsilon(1S) \to J/\psi+\chi_{c1} and search for double-charmonium production in ΄(1S)\Upsilon(1S) and ΄(2S)\Upsilon(2S) decays

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    Using data samples of 102×106102\times10^6 ΄(1S)\Upsilon(1S) and 158×106158\times10^6 ΄(2S)\Upsilon(2S) events collected with the Belle detector, a first experimental search has been made for double-charmonium production in the exclusive decays ΄(1S,2S)→J/ψ(ψâ€Č)+X\Upsilon(1S,2S)\rightarrow J/\psi(\psi')+X, where X=ηcX=\eta_c, χcJ(J= 0, 1, 2)\chi_{cJ} (J=~0,~1,~2), ηc(2S)\eta_c(2S), X(3940)X(3940), and X(4160)X(4160). No significant signal is observed in the spectra of the mass recoiling against the reconstructed J/ψJ/\psi or ψâ€Č\psi' except for the evidence of χc1\chi_{c1} production with a significance of 4.6σ4.6\sigma for ΄(1S)→J/ψ+χc1\Upsilon(1S)\rightarrow J/\psi+\chi_{c1}. The measured branching fraction \BR(\Upsilon(1S)\rightarrow J/\psi+\chi_{c1}) is (3.90±1.21(stat.)±0.23(syst.))×10−6(3.90\pm1.21(\rm stat.)\pm0.23 (\rm syst.))\times10^{-6}. The 90%90\% confidence level upper limits on the branching fractions of the other modes having a significance of less than 3σ3\sigma are determined. These results are consistent with theoretical calculations using the nonrelativistic QCD factorization approach.Comment: 12 pages, 4 figures, 1 table. The fit range was extended to include X(4160) signal according to referee's suggestions. Other results unchanged. Paper was accepted for publication as a regular article in Physical Review

    Measurement of nuclear modification factors of gamma(1S)), gamma(2S), and gamma(3S) mesons in PbPb collisions at root s(NN)=5.02 TeV

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    The cross sections for ϒ(1S), ϒ(2S), and ϒ(3S) production in lead-lead (PbPb) and proton-proton (pp) collisions at √sNN = 5.02 TeV have been measured using the CMS detector at the LHC. The nuclear modification factors, RAA, derived from the PbPb-to-pp ratio of yields for each state, are studied as functions of meson rapidity and transverse momentum, as well as PbPb collision centrality. The yields of all three states are found to be significantly suppressed, and compatible with a sequential ordering of the suppression, RAA(ϒ(1S)) > RAA(ϒ(2S)) > RAA(ϒ(3S)). The suppression of ϒ(1S) is larger than that seen at √sNN = 2.76 TeV, although the two are compatible within uncertainties. The upper limit on the RAA of ϒ(3S) integrated over pT, rapidity and centrality is 0.096 at 95% confidence level, which is the strongest suppression observed for a quarkonium state in heavy ion collisions to date. © 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.Peer reviewe

    Measurement of b jet shapes in proton-proton collisions at root s=5.02 TeV