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

• Main Authors: Sirunyan, A. M., Tumasyan, A. R., Adam, Wolfgang, Ambrogi, Federico, Asilar, Ece, Md. Ali, Mohd. Adli
• Format: Article
• Language: English; English; English
• Published: Springer Nature 2019
• Subjects: Q Science (General); QC Physics
• Online Access: http://irep.iium.edu.my/71633/1/71633_Search%20for%20rare%20decays%20of%20Z%20and%20Higgs_article.pdf; http://irep.iium.edu.my/71633/2/71633_Search%20for%20rare%20decays%20of%20Z%20and%20Higgs_scopus.pdf; http://irep.iium.edu.my/71633/3/71633_Search%20for%20rare%20decays%20of%20Z%20and%20Higgs_wos.pdf; http://irep.iium.edu.my/71633/; https://link.springer.com/content/pdf/10.1140%2Fepjc%2Fs10052-019-6562-5.pdf

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.