Measurement of WWZ and ZH production cross sections at $\sqrt{s}$ = 13 and 13.6 TeV

TL;DR

This paper reports the first measurements of WWZ and ZH production cross sections at 13 and 13.6 TeV, providing evidence for triboson production and testing the Standard Model predictions with high significance.

Contribution

It presents the first simultaneous measurement of nonresonant WWZ and ZH production processes at these energies, with separate and combined signal strength determinations.

Findings

Measured signal strengths close to SM predictions.

First evidence of triboson production at 13.6 TeV.

High significance (over 4 sigma) for combined signal detection.

Abstract

A measurement is presented of the cross section in proton-proton collisions for the production of two W bosons and one Z boson. It is based on data recorded by the CMS experiment at the CERN LHC at center-of-mass energies $\sqrt{s}$ = 13 and 13.6 TeV, corresponding to an integrated luminosity of 200 fb$^{-1}$. Events with four charged leptons (electrons or muons) in the final state are selected. Both nonresonant WWZ production and ZH production, with the Higgs boson decaying into two W bosons, are reported. For the first time, the two processes are measured separately in a simultaneous fit. Combining the two modes, signal strengths relative to the standard model (SM) predictions of 0.75 $^{+0.34}_{-0.29}$ and 1.74 $^{+0.71}_{-0.60}$ are measured for $\sqrt{s}$ = 13 and 13.6 TeV, respectively. The observed (expected) significance for the triboson signal is 3.8 (2.5) standard deviations for $\sqrt{s}$ = 13.6 TeV, thus providing the first evidence for triboson production at this center-of-mass energy. Combining the two modes and the two center-of-mass energies, the inclusive signal strength relative to the SM prediction is measured to be 1.03 $^{+0.31}_{-0.28}$, with an observed (expected) significance of 4.5 (5.0) standard deviations.