New CLEO Results for |V_cb| and |V_ub|

TL;DR

This paper presents recent CLEO measurements of spectral moments in B decays, enabling more precise extraction of CKM matrix elements |V_cb| and |V_ub| by reducing model dependence and updating previous results.

Contribution

It introduces new experimental measurements that refine the determination of |V_cb| and |V_ub|, improving accuracy through spectral moments and updated analyses.

Findings

More precise |V_cb| and |V_ub| values obtained

Reduced model dependence in CKM element extraction

Updated measurement of |V_cb| from B -> D* l nu at zero recoil

Abstract

We report recent measurements from CLEO of the first two moments of the photon energy spectrum for b -> s gamma decays and the hadronic recoil mass in B -> X_c l nu. These physical quantities allow one to fix non-perturbative parameters occurring in calculations based on HQET and QCD. Predictions for semileptonic decay rates within this same framework depend in addition on the CKM matrix elements V_qq' governing quark mixing. We can thus extract |V_cb| from the inclusive semileptonic decay rate of B mesons, and |V_ub| from the lepton endpoint spectrum of B -> X_u l nu. Model dependence is reduced except for the assumption of quark-hadron duality. Finally, we update the classic measurement of |V_cb| from B -> D* l nu at zero recoil.