Search for heavy particles in the $b$-tagged dijet mass distribution with additional $b$-tagged jets in proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS experiment

TL;DR

This paper reports a search for new heavy particles decaying into $b$-quark pairs in proton-proton collisions at 13 TeV, using advanced $b$-tagging and data-driven background estimation to set limits on potential signals.

Contribution

The study introduces an optimized $b$-tagging strategy and a novel data-driven background estimation method for improved sensitivity in heavy particle searches.

Findings

No significant excess observed over background.

Upper limits set on heavy vector-boson production cross section.

Method enhances sensitivity for future heavy particle searches.

Abstract

A search optimized for new heavy particles decaying to two $b$-quarks and produced in association with additional $b$-quarks is reported. The sensitivity is improved by $b$-tagging at least one lower-$p_{\rm{T}}$ jet in addition to the two highest-$p_{\rm{T}}$ jets. The data used in this search correspond to an integrated luminosity of 103 $\text{fb}^{-1}$ collected with a dedicated trijet trigger during the 2017 and 2018 $\sqrt{s} = 13$ TeV proton-proton collision runs with the ATLAS detector at the LHC. The search looks for resonant peaks in the $b$-tagged dijet invariant mass spectrum over a smoothly falling background. The background is estimated with an innovative data-driven method based on orthonormal functions. The observed $b$-tagged dijet invariant mass spectrum is compatible with the background-only hypothesis. Upper limits at 95% confidence level on a heavy vector-boson production cross section times branching ratio to a pair of $b$-quarks are derived.