Please use this identifier to cite or link to this item: http://bura.brunel.ac.uk/handle/2438/17337
Title: Observation of the Z →ψ + - Decay in pp Collisions at s =13 TeV
Authors: Sirunyan, AM
Tumasyan, A
Adam, W
Ambrogi, F
Asilar, E
Bergauer, T
Brandstetter, J
Brondolin, E
Dragicevic, M
Erö, J
Escalante Del Valle, A
Flechl, M
Frühwirth, R
Ghete, VM
Hrubec, J
Jeitler, M
Krammer, N
Krätschmer, I
Liko, D
Madlener, T
Mikulec, I
Rad, N
Rohringer, H
Schieck, J
Schöfbeck, R
Spanring, M
Spitzbart, D
Taurok, A
Waltenberger, W
Wittmann, J
Wulz, CE
Zarucki, M
Chekhovsky, V
Mossolov, V
Suarez Gonzalez, J
De Wolf, EA
Di Croce, D
Janssen, X
Lauwers, J
Pieters, M
Van De Klundert, M
Van Haevermaet, H
Van Mechelen, P
Van Remortel, N
Abu Zeid, S
Blekman, F
D'Hondt, J
De Bruyn, I
De Clercq, J
Deroover, K
Flouris, G
Lontkovskyi, D
Lowette, S
Marchesini, I
Moortgat, S
Moreels, L
Python, Q
Skovpen, K
Tavernier, S
Van Doninck, W
Van Mulders, P
Van Parijs, I
Beghin, D
Bilin, B
Brun, H
Clerbaux, B
De Lentdecker, G
Delannoy, H
Dorney, B
Fasanella, G
Favart, L
Goldouzian, R
Grebenyuk, A
Kalsi, AK
Lenzi, T
Luetic, J
Postiau, N
Starling, E
Thomas, L
Vander Velde, C
Vanlaer, P
Vannerom, D
Wang, Q
Cornelis, T
Dobur, D
Fagot, A
Gul, M
Khvastunov, I
Poyraz, D
Roskas, C
Trocino, D
Tytgat, M
Verbeke, W
Vermassen, B
Vit, M
Issue Date: 2018
Publisher: American Physical Society
Citation: Physical Review Letters, 2018, 121 (14)
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.
URI: http://bura.brunel.ac.uk/handle/2438/17337
DOI: http://dx.doi.org/10.1103/PhysRevLett.121.141801
ISSN: 0031-9007
Appears in Collections:Dept of Electronic and Computer Engineering Research Papers

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