Radiative B decay spectrum: DGE at NNLO
- Jeppe R. Andersena
The photon energy spectrum in inclusive weak radiative B̄ → Xsγ decay is computed to order αsβ0. This result is used to extract a value for the HQET parameter Λ̄ from the average 〈1 − 2Eγ/mB〉, and a value of the parameter λ1 from 〈(1 − 2Eγ/mB)〉. An accurate measurement of 〈1 − 2Eγ/mB〉 can determine the size of the nonperturbative contributions to the Υ(1S) mass which cannot be absorbed into the b quark pole mass.