Hadron Spectra and Spectral Moments in the Decay B \to X_s \ell^+ \ell^- using HQET

Abstract

We compute the 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^- in standard model using the heavy quark expansion technique (HQET). Results for the first two hadronic moments < S_H^n> and <E_H^n>, n=1,2, are presented here 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 can be combined with the analysis of semileptonic decays B \to X \ell \nu_\ell to determine them precisely.