RD(*) and survival of the fittest scalar leptoquark

Abstract

Motivated by the long-standing discrepancy in lepton flavor universality ratios RD and RD* we assess the status of scalar leptoquark states R2, R˜2 and S1 which can in principle provide a desired enhancement of B(B→D(*)τν) in a minimal setup with two Yukawa couplings only. We consider unavoidable low-energy constraints, Z-pole measurements as well as high-pT constraints. After setting the mass of each leptoquark to 1.5 TeV we find that of all considered states only S1 leptoquark, coupled to both chiralities of leptons and quarks, is still a completely viable solution while the scenario with R2 is in growing tension with Γ(Z→ττ) and with the LHC constraints on the ditau tails at high-pT. We comment on the future experimental tests of the S1 scenario. Published by the American Physical Society 2024