What are the right values of $\bar{\Lambda }$ and the heavy quark kinetic energy?

Abstract

The values of two important parameters of the heavy quark effective theory,\, $\bar{\Lambda }$ and ${\mu }_{\pi }^2$ (the mean value of the heavy quark three momentum squared),\, have been determined recently in \cite {GKLW} from the precise CLEO data on the shape of the electron spectrum in semileptonic B meson decays. The values obtained in \cite{GKLW}: $\bar{\Lambda }=(0.55\pm 0.05)GeV,{\mu }_{\pi }^2=(0.35\pm 0.05)Ge{V}^2,$ disagree with the result obtained earlier in \cite{CH} from the D meson semileptonic width. The purpose of this note is to show that the main reason for a disagreement is the secondary electron background present in the data,\, which influences strongly the extracted values of $\bar{\lambda }$ and ${\mu }_{\pi }^2$. We determine the amount of this background from the selfconsistency conditions,\, and subtract it out. As a result,\, the values of $\bar{\Lambda }$ and ${\mu }_{\pi }^2$ become a factor two smaller and agree with \cite{CH}.

Comments: Plain TeX, 13 pages, 1 eps figure; unfortunately, the correction sent was in error, while the original version was right and is reinstated