Speaker
Description
Ratios of isospin amplitudes in hadron decays are a useful probe of the interplay between weak and strong interactions, and allow searches for physics beyond the Standard Model. We present the first results on isospin amplitudes in b-baryon decays, using data corresponding to an integrated luminosity of 8.5 fb^−1, collected with the LHCb detector in pp collisions at center of mass energies of 7, 8 and 13 TeV. The isospin amplitude ratio |A1(Λb→J/ψ Σ^0)/A0(Λb→J/ψ Λ)|, where the subscript on A indicates the final-state isospin, is measured to be less than 1/21.8 at 95\% confidence level. The Cabibbo suppressed Ξb^0→J/ψΛ decay is observed for the first time, allowing for the measurement |A0(Ξb^0→J/ψ Λ)/A1/2(Ξb^0→J/ψ Ξ^0)|=0.37±0.06±0.02, where the uncertainties are statistical and systematic, respectively.
