# Recent diboson and multiboson results in ATLAS

## TL;DR

This paper reports recent ATLAS measurements of diboson and multiboson production at 13 TeV, including cross sections, boson helicities, and limits on anomalous couplings, with first evidence for three-boson production.

## Contribution

It presents the first evidence for three massive vector boson production and detailed measurements of diboson processes at the LHC, including helicity and anomalous coupling analyses.

## Key findings

- Measured fiducial cross sections agree with Standard Model predictions.
- Probed helicities of W and Z bosons in WZ channel.
- Set limits on anomalous gauge couplings.

## Abstract

Recent measurements of the associated production of two or three massive vector bosons in proton-proton collisions at the Large Hadron Collider, collected by the ATLAS detector at a centre-of-mass energy of $\sqrt{s} = 13$ TeV, are reported. The diboson analyses target the production and decay modes $WW\rightarrow e\nu_e\mu\nu_\mu$, $WZ \rightarrow \ell^{\prime} \nu \ell \ell\,(\ell = e, \mu)$, $ZZ \rightarrow \ell\ell\nu\nu$, and the $4\ell$ final state. Fiducial inclusive cross sections are compared to state-of-the-art Standard Model calculations and several unfolded differential distributions are measured. In the $WZ$ channel, the helicities of the $W$ and $Z$ bosons are probed. Results are interpreted in terms of limits on anomalous gauge couplings in the framework of effective field theories. Finally, the first evidence for the production of three massive vector bosons ($WWW$, $WWZ$, $WZZ$) is presented.