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). © 2018 CERN, for the CMS Collaboration.

Observation of the Z →ψ + - Decay in pp Collisions at s =13 TeV / Sirunyan A.M., Tumasyan A., Adam W., Ambrogi F., Asilar E., Bergauer T., Brandstetter J., Brondolin E., Dragicevic M., Ero J., Escalante Del Valle A., Flechl M., Fruhwirth R., Ghete V.M., Hrubec J., Jeitler M., Krammer N., Kratschmer I., Liko D., Madlener T., et al.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - ELETTRONICO. - 121:(2018), pp. 0-0. [10.1103/PhysRevLett.121.141801]

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

Chatterjee K.;Ciulli V.;D'Alessandro R.;Focardi E.;Latino G.;Lenzi P.;Russo L.;Viliani L.;
2018

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). © 2018 CERN, for the CMS Collaboration.
2018
121
0
0
Sirunyan A.M.; Tumasyan A.; Adam W.; Ambrogi F.; Asilar E.; Bergauer T.; Brandstetter J.; Brondolin E.; Dragicevic M.; Ero J.; Escalante Del Valle A.;...espandi
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/1176383
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