Corrections to moments of the photon spectrum in the inclusive decayB→Xsγ

We investigate the two main uncertainties on the extraction of the nonperturbative matrix elements $\overline{\Lambda }$ and ${\lambda }_1$ from moments of the inclusive rare FCNC decay $\overrightarrow{B}{X}_s\gamma .$ The first one is due to unknown matrix elements of higher dimensional operators which are estimated by varying the matrix elements in a range as suggested by dimensional analysis. The effect of these terms is found to be small. A second uncertainty arises from a cut on the photon energy and we give model independent bounds on these uncertainties as well as their estimates from a simplified version of the ACCMM model.