# Search for long-lived neutral particles in $pp$ collisions at $\sqrt{s}$ = 13 TeV that decay into displaced hadronic jets in the ATLAS calorimeter

## TL;DR

This paper reports a search for long-lived neutral particles decaying into displaced hadronic jets in the ATLAS detector at 13 TeV, setting limits on their production without observing a significant excess.

## Contribution

It introduces a novel search strategy for long-lived neutral particles decaying within the ATLAS calorimeter, extending sensitivity to new physics scenarios.

## Key findings

- No significant excess observed.
- Limits set on production cross section times branching ratio.
- Constraints on long-lived particle decay lengths.

## Abstract

This paper describes a search for pairs of neutral, long-lived particles decaying in the ATLAS calorimeter. Long-lived particles occur in many extensions to the Standard Model and may elude searches for new promptly decaying particles. The analysis considers neutral, long-lived scalars with masses between 5 GeV and 400 GeV, produced from decays of heavy bosons with masses between 125 GeV and 1000 GeV, where the long-lived scalars decay into Standard Model fermions. The analysis uses either 10.8 fb$^{-1}$ or 33.0 fb$^{-1}$ of data (depending on the trigger) recorded in 2016 at the LHC with the ATLAS detector in proton-proton collisions at a centre-of-mass energy of 13 TeV. No significant excess is observed, and limits are reported on the production cross section times branching ratio as a function of the proper decay length of the long-lived particles.