A search for new phenomena is presented in final states with two leptons and one or no b-tagged jets. The event selection requires the two leptons to have opposite charge, the same flavor (electrons or muons), and a large invariant mass. The analysis is based on the full run-2 proton-proton collision dataset recorded at a center-of-mass energy of s=13 TeV by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 139 fb-1. No significant deviation from the expected background is observed in the data. Inspired by the B-meson decay anomalies, a four-fermion contact interaction between two quarks (b, s) and two leptons (ee or μμ) is used as a benchmark signal model, which is characterized by the energy scale and coupling, Λ and g∗, respectively. Contact interactions with Λ/g∗ lower than 2.0 (2.4) TeV are excluded for electrons (muons) at the 95% confidence level, still far below the value that is favored by the B-meson decay anomalies. Model-independent limits are set as a function of the minimum dilepton invariant mass, which allow the results to be reinterpreted in various signal scenarios.

Search for New Phenomena in Final States with Two Leptons and One or No b -Tagged Jets at s =13 TeV Using the ATLAS Detector

Barberis D.;Gagliardi G.;Parodi F.;Sannino M.;