Perturbative QCD and Power Corrected Hadron Spectra and Spectral Moments in the Decays $B\to X_s{\ell }^{+}{\ell }^{-}$

Abstract

Leading order (in ${\alpha }_s$) perturbative QCD and power ($1/m_b^2)$ corrections to the hadronic invariant mass and hadron energy spectra in the decay $B\to X_s{\ell }^{+}{\ell }^{-}$ are reviewed in the standard model using the heavy quark expansion technique (HQET). In particular, the first two hadronic moments $<S_H^n>$ and $<E_H^n>$, $n=1,2$, are presented working out their sensitivity on the HQET parameters ${\lambda }_1$ and $\bar{\Lambda }$. Data from the forthcoming B facilities can be used to measure the short-distance contribution in $B\to X_s{\ell }^{+}{\ell }^{-}$ and determine the HQET parameters from the moments $<S_H^n>$. This could be combined with complementary constraints from the decay $B\to X\ell {\nu }_{\ell }$ to determine these parameters precisely.

Comments: 7 pages, 3 figures (requires ltwol2e.sty, included). To appear in the Proceedings of the XXIX International Conference on High Energy Physics, Vancouver, B.C., Canada, July 23-29,1998