The B -> X_s gamma Photon Spectrum

Abstract

The photon energy spectrum in inclusive weak radiative B -> X_s gamma decay is computed to order alpha_s^2 beta_0. This result is used to extract a value for the HQET parameter $\bar{\Lambda }$ from the average <1-2E_\gamma/m_B>, and a value of the parameter ${\lambda }_1$ from <(1-2E_\gamma/m_B)^2>. An accurate measurement of <1-2E_\gamma/m_B> can determine the size of the nonperturbative contributions to the Upsilon(1S) mass which cannot be absorbed into the b quark pole mass.

Comments: 16 pages, RevTeX