A search is presented for decays of Z and Higgs bosons to a J/ψ meson and a photon, with the subsequent decay of the J/ψ to μ+μ-. The analysis uses data from proton-proton collisions with an integrated luminosity of 35.9 fb-1 at √s =13 TeV collected with the CMS detector at the LHC. The observed limit on the Z → J/ψγ decay branching fraction, assuming that the J/ψ meson is produced unpolarized, is 1.4 × 10^-6 at 95% confidence level, which corresponds to a rate higher than expected in the standard model by a factor of 15. For extreme-polarization scenarios, the observed limit changes from - 13.6 to + 8.6 % with respect to the unpolarized scenario. The observed upper limit on the branching fraction for H → J/ψγ where the J/ψ meson is assumed to be transversely polarized is 7.6 × 10^-4, a factor of 260 larger than the standard model prediction. The results for the Higgs boson are combined with previous data from proton-proton collisions at √s = 8 TeV to produce an observed upper limit on the branching fraction for H → J/ψγ that is a factor of 220 larger than the standard model value.

Search for rare decays of Z and Higgs bosons to J/ψ and a photon in proton-proton collisions at √s = 13 TeV

Meridiani P.;Amapane N.;Argiro' S.;Bellan R.;Costa M.;Covarelli R.;Kiani B.;Migliore E.;Monaco V.;Monteil E.;Obertino M. M.;Pacher L.;Angioni G. L. P.;Romero A.;Sacchi R.;Sola V.;Solano A.;Soldi D.;
2019-01-01

Abstract

A search is presented for decays of Z and Higgs bosons to a J/ψ meson and a photon, with the subsequent decay of the J/ψ to μ+μ-. The analysis uses data from proton-proton collisions with an integrated luminosity of 35.9 fb-1 at √s =13 TeV collected with the CMS detector at the LHC. The observed limit on the Z → J/ψγ decay branching fraction, assuming that the J/ψ meson is produced unpolarized, is 1.4 × 10^-6 at 95% confidence level, which corresponds to a rate higher than expected in the standard model by a factor of 15. For extreme-polarization scenarios, the observed limit changes from - 13.6 to + 8.6 % with respect to the unpolarized scenario. The observed upper limit on the branching fraction for H → J/ψγ where the J/ψ meson is assumed to be transversely polarized is 7.6 × 10^-4, a factor of 260 larger than the standard model prediction. The results for the Higgs boson are combined with previous data from proton-proton collisions at √s = 8 TeV to produce an observed upper limit on the branching fraction for H → J/ψγ that is a factor of 220 larger than the standard model value.
2019
79
94
1
27
http://dx.doi.org/10.1140/epjc/s10052-019-6562-5
LHC, CMS, pp collisions, Higgs, J/ψ meson
Sirunyan A.M.; Tumasyan A.; Adam W.; Ambrogi F.; Asilar E.; Bergauer T.; Brandstetter J.; Dragicevic M.; Ero J.; Del Valle A.E.; Flechl M.; Fruhwirth ...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1768606
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