# Measurement of the $t\bar{t}t\bar{t}$ production at 13 TeV with the ATLAS detector at the LHC

### Submission summary

 As Contributors: O. Ogul Oncel Preprint link: scipost_202107_00049v1 Date submitted: 2021-07-23 10:30 Submitted by: Oncel, O. Ogul Submitted to: SciPost Physics Proceedings Proceedings issue: DIS2021 Academic field: Physics Specialties: High-Energy Physics - Experiment Approach: Experimental

### Abstract

Two measurements and their combination for the $t\bar{t}t\bar{t}$ production cross-section analysis using 139 fb$^{-1}$ of proton$-$proton collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the LHC are presented. The first analysis uses the final states with either one or two opposite-sign leptons (electrons or muons). In the second analysis the final states with either two same-sign or at least three leptons are considered. With an observed (expected) significance of 4.3 (2.4) standard deviations over the background-only hypothesis, the second analysis provides the first evidence for the $t\bar{t}t\bar{t}$ process. No significant deviations from the Standard Model are observed.

###### Current status:
Editor-in-charge assigned