A measurement of the fiducial cross section of the associated production of a Z boson and a high-pT 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 √ 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 pT greater than 225 GeV is produced in association with a Z, and the Z decays to a νν pair (Z(νν)γ ), is measured to be 23.3 +1.4 −1.3 fb, in agreement, within uncertainties, with the standard model prediction. The differential cross section as a function of the photon pT 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 Zγ γ vertex using the pT spectrum of the photons. The observed 95% confidence level intervals for CP-conserving hγ3 and hγ4 are determined to be (−3.4, 3.5)×10−4 and (−6.8, 6.8)×10−7, and for h Z3 and h Z4 they are (−2.2, 2.2)×10−4 and (−4.1, 4.2)×10−7, respectively. These are the strictest limits to date on hγ3, hZ3 and hZ4.

Measurement of the Zγ production cross section and search for anomalous neutral triple gauge couplings in pp collisions at √s = 13 TeV

Alexe, C.;Bruschini, D.;Ligabue, F.;
2026

Abstract

A measurement of the fiducial cross section of the associated production of a Z boson and a high-pT 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 √ 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 pT greater than 225 GeV is produced in association with a Z, and the Z decays to a νν pair (Z(νν)γ ), is measured to be 23.3 +1.4 −1.3 fb, in agreement, within uncertainties, with the standard model prediction. The differential cross section as a function of the photon pT 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 Zγ γ vertex using the pT spectrum of the photons. The observed 95% confidence level intervals for CP-conserving hγ3 and hγ4 are determined to be (−3.4, 3.5)×10−4 and (−6.8, 6.8)×10−7, and for h Z3 and h Z4 they are (−2.2, 2.2)×10−4 and (−4.1, 4.2)×10−7, respectively. These are the strictest limits to date on hγ3, hZ3 and hZ4.
2026
Settore PHYS-01/A - Fisica sperimentale delle interazioni fondamentali e applicazioni
Beyond Standard Model, Hadron-Hadron Scattering, Particle and Resonance Production, Photon Production
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/170707
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