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 Electrical Engineering Research Papers
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