Speaker
Dr
Matteo Palutan
(LNF -INFN)
Description
At present, the first-row constraint, $|V_{ud}|^2 + |V_{us}|^2 +
|V_{ub}|^2$ = 1 (with $|V_{ub}|^2$ negligible), offers the most
precise test of CKM unitarity.
Up until 2002 (and for the 2004 PDG evaluation), the evaluation
of $|V_{us}$ from older $K_{l3}$ data gave 2.3$\sigma$ hint of
unitarity violation in the first-row test. The 2003 measurement
of BR($K^+_{e2}$) by BNL E865 gave a value for $|V_{us}|$
consistent with unitarity. In the period 2004-2006, many new
measurements of BRs, lifetimes, and form-factor slopes were
announced by KLOE, KTeV, ISTRA+ and NA48. All of these new
measurements are distinguished from the older measurements in
that they are based on much higher statistics, and in that
radiative corrections are applied consistently. The 2006 PDG
review on $|V_{us}$ includes many, but not all, of these
important developments. I will present an up-to-date evaluation
that includes preliminary results presented at this conference.
