Observation of the Z →ψ + - decay in pp collisions at s =13 TeV

Sirunyan, A.M. and Tumasyan, A. R. and Adam, Wolfgang and Asilar, Ece and Bergauer, Thomas and Md. Ali, Mohd. Adli (2018) Observation of the Z →ψ + - decay in pp collisions at s =13 TeV. Physical Review Letters, 121 (14). pp. 1-17. ISSN 0031-9007 E-ISSN 1079-7114

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Abstract

This Letter presents the observation of the rare Z boson decay Z → ψlþl−. Here, ψ represents contributions from direct J=ψ and ψð2SÞ → J=ψX, lþl− is a pair of electrons or muons, and the J=ψ meson is detected via its decay to μþμ−. 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 ψð2SÞ → J=ψX contribution, the ratio of the branching fraction of the exclusive decay Z → J=ψlþl− to the decay Z → μþμ−μþμ− within a fiducial phase space is measured to be BðZ → J=ψlþl−Þ= BðZ → μþμ−μþμ−Þ ¼ 0.67 0.18ðstatÞ 0.05ðsystÞ.

Item Type:	Article (Journal)
Additional Information:	7861/70337
Uncontrolled Keywords:	Z →ψ + - decay; PP collisions; S =13 TeV
Subjects:	Q Science > Q Science (General) Q Science > QC Physics
Kulliyyahs/Centres/Divisions/Institutes (Can select more than one option. Press CONTROL button):	Kulliyyah of Science Kulliyyah of Science > Department of Physics
Depositing User:	Dr Mohd Adli MD Ali
Date Deposited:	30 Jan 2019 10:05
Last Modified:	15 Jul 2019 09:35
URI:	http://irep.iium.edu.my/id/eprint/70337

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