Search for diboson resonances in the 2$\ell$2$\nu$ final state in proton-proton collisions at 13 TeV

TL;DR

This paper searches for heavy resonances decaying into Z boson pairs in proton-proton collisions at 13 TeV, setting limits on possible new particles like bulk gravitons and exploring different production mechanisms.

Contribution

It provides the most stringent limits to date on bulk graviton models in the 800 GeV mass range and examines various production scenarios for heavy resonances.

Findings

Excluded bulk graviton masses below 800 GeV for certain model parameters.

Set upper limits on cross section times branching ratio for resonances between 600 and 2500 GeV.

Analyzed different production mechanisms, including gluon-gluon fusion and quark-antiquark annihilation.

Abstract

A search for heavy resonances decaying to a pair of Z bosons is performed using data collected with the CMS detector at the LHC. Events are selected by requiring two oppositely charged leptons (electrons or muons), consistent with the decay of a Z boson, and large missing transverse momentum, which is interpreted as arising from the decay of a second Z boson to two neutrinos. The analysis uses data from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The hypothesis of a spin-2 bulk graviton (X) decaying to a pair of Z bosons is examined for 600 $\le m_\mathrm{X} \le$ 2500 GeV and upper limits at 95% confidence level are set on the product of the production cross section and branching fraction of X $\to$ ZZ ranging from 100 to 4 fb. For bulk graviton models characterized by a curvature scale parameter $\tilde{k} =$ 0.5 in the extra dimension, the region $m_\mathrm{X} < $ 800 GeV is excluded, providing the most stringent limit reported to date. Variations of the model considering the possibility of a wide resonance produced exclusively via gluon-gluon fusion or $\mathrm{q}\overline{\mathrm{q}}$ annihilation are also examined.