Measurement of the Zγ production cross section and search for anomalous neutral triple gauge couplings in pp collisions at $$ sqrt{s}=13 $$ TeV
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abstract
; A; bstract; ; ; A measurement of the fiducial cross section of the associated production of a Z boson and a high-; p; T; photon, where the Z decays to two neutrinos, and a search for anomalous triple gauge couplings are reported. The results are based on data collected by the CMS experiment at the LHC in proton-proton collisions at; ; ; $$ sqrt{s}=13 $$; ; ; s; ; =; 13; ; ; ; TeV during 2016–2018, corresponding to an integrated luminosity of 138 fb; ; −; 1; ; . The fiducial Zγ cross section, where a photon with a; p; T; greater than 225 GeV is produced in association with a Z, and the Z decays to a; ; ; $$ upnu overline{upnu} $$; ; ν; ; ν; ¯; ; ; ; ; pair; ; ; $$ left(mathrm{Z}left(upnu overline{upnu}right)upgamma right) $$; ; ; ; Z; ; ; ν; ; ν; ¯; ; ; ; γ; ; ; ; ; ; , is measured to be; ; ; $$ {23.3}_{-1.3}^{+1.4} $$; ; ; 23.3; ; −; 1.3; ; ; +; 1.4; ; ; ; ; ; fb, in agreement, within uncertainties, with the standard model prediction. The differential cross section as a function of the photon; p; T; has been measured and compared with standard model predictions computed at next-to-leading and at next-to-next-to-leading order in perturbative quantum chromodynamics. Constraints have been placed on the presence of anomalous couplings that affect the ZZγ and Zγγ vertex using the; p; T; spectrum of the photons. The observed 95% confidence level intervals for; CP; -conserving; ; ; $$ {h}_3^{upgamma} $$; ; ; h; 3; γ; ; ; ; ; and; ; ; $$ {h}_4^{upgamma} $$; ; ; h; 4; γ; ; ; ; ; are determined to be (; −; 3.4, 3.5); ×; 10; ; −; 4; ; and (; −; 6.8, 6.8); ×; 10; ; −; 7; ; , and for; ; ; $$ {h}_3^{mathrm{Z}} $$; ; ; h; 3; Z; ; ; ; ; and; ; ; $$ {h}_4^{mathrm{Z}} $$; ; ; h; 4; Z; ; ; ; ; they are (; −; 2.2, 2.2); ×; 10; ; −; 4; ; and (; −; 4.1, 4.2); ×; 10; ; −; 7; ; , respectively. These are the strictest limits to date on; ; ; $$ {h}_3^{upgamma} $$; ; ; h; 3; γ; ; ; ; ; ,; ; ; $$ {h}_3^{mathrm{Z}} $$; ; ; h; 3; Z; ; ; ; ; and; ; ; $$ {h}_4^{mathrm{Z}} $$; ; ; h; 4; Z; ; ; ; ; .;
