Estudo do acoplamento anômalo γγZZ com o detector CT-PPS no CMS/LHC

Abstract

In this work a study of central exclusive ZZ production by two photon exchange, pp - p + ZZ + p, is presented. The fully leptonic channel is considered, with the Z bosons decaying to pairs of muons or electrons. The feasibility to observe such process is investigated using the CMS and CT-PPS detectors, with proton-proton collisions at a center-of-mass energy of 13TeV and integrated luminosity of 100 fb−1. This channel is tree-level forbidden in the Standard Model and therefore a model with an anomalous γγZZ coupling is considered with varying values of the coupling parameters. The main background due to the mixture of outgoing protons from so-called pileup events, combined with exclusive ZZ events and especially with those from the inclusive production of Z boson pairs is studied. It is shown that even without the use of timing detectors in the CT-PPS system, for the measurement of scattered protons from the interaction point at very low angles, the background from pileup events can be considerably suppressed. The sensitivity to this channel was studied in the range of values of the anomalous coupling aZ0/⇤2 & 5 · 10−6 GeV−2 using a dipole form factor with an energy cuto↵ ⇤cutoff = 2TeV.