Search for nonresonant new physics signals in high-mass dilepton events produced in association with b-tagged jets in proton-proton collisions at √s = 13 TeV

A search for nonresonant new physics phenomena in high-mass dilepton eventsproduced in association with b-tagged jets is performed using proton-proton collision datacollected in 2016–2018 by the CMS experiment at the CERN LHC, at a center-of-mass energyof 13 TeV corresponding to an integrated luminosity of 138 fb⁻¹. The analysis considers twoeffective field theory models with dimension-six operators; involving four-fermion contactinteractions between two leptons (ℓℓ, electrons or muons) and b or s quarks (bbℓℓ and bsℓℓ).Two lepton flavor combinations (ee and µµ) are required and events are classified as having 0,1, or ≥2 b-tagged jets in the final state. No significant excess is observed over the standardmodel backgrounds. Upper limits are set on the production cross section of the new physicssignals. These translate into lower limits on the energy scale Λ of 6.9 to 9.0 TeV in the bbℓℓmodel, depending on model parameters, and on the ratio of energy scale and effective coupling,Λ/g_∗, of 2.0 to 2.6 TeV in the bsℓℓ model. Lepton flavor universality is also tested by comparingthe dielectron (ee) and dimuon (µµ) mass spectra for different b-tagged jet multiplicities. Nosignificant deviation from the standard model expectation of unity is observed.