Theoretical predictions for inclusive B → Xuτ(ν)over-bar decay

With the expected large increase in datasets, previously not measured decays will be studied at Belle II. We derive standard model predictions for the B -> X-u tau(nu) over bar. decay rate and distributions. The region in the lepton energy spectrum where higher-dimension operators in the local operator product expansion need to be resummed into the b-quark light-cone distribution function is a significantly greater fraction of the phase space than for massless leptons. The finite tau mass has the novel effect of shifting and squeezing how the distribution function enters the lepton energy spectrum. We also derive new predictions for the tau polarization.

Automated summary

With the expected large increase in datasets, previously unmeasured decays will be studied at Belle II, including predictions for the decay rate, distributions, and polarization.