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Observation of the Z →ψ + - Decay in pp Collisions at s =13 TeV
Journal article   Open access   Peer reviewed

Observation of the Z →ψ + - Decay in pp Collisions at s =13 TeV

CMS Collaboration, B. Bilki, W Clarida, K Dilsiz, S. Durgut, R. P. Gandrajula, M. Haytmyradov, V. Khristenko, J-P Merlo, A Mestvirishvili, …
Physical review letters, Vol.121(14), 141801
2018
DOI: 10.1103/PhysRevLett.121.141801
PMID: 30339440
url
https://doi.org/10.1103/PhysRevLett.121.141801View
Published (Version of record) Open Access

Abstract

This Letter presents the observation of the rare Z boson decay Z→ψ + -. Here, ψ represents contributions from direct J/ψ and ψ(2S)→J/ψX, + - is a pair of electrons or muons, and the J/ψ meson is detected via its decay to μ+μ-. The sample of proton-proton collision data, collected by the CMS experiment at the LHC at a center-of-mass energy of 13 TeV, corresponds to an integrated luminosity of 35.9 fb-1. The signal is observed with a significance in excess of 5 standard deviations. After subtraction of the ψ(2S)→J/ψX contribution, the ratio of the branching fraction of the exclusive decay Z→J/ψ + - to the decay Z→μ+μ-μ+μ- within a fiducial phase space is measured to be B(Z→J/ψ + -)/B(Z→μ+μ-μ+μ-)=0.67±0.18(stat)±0.05(syst).
High Energy Physics Physics

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