Speaker
Ms
Anne Dabrowski
(Department of Physics and Astronomy, Northwestern University)
Description
Measured ratios of decay rates for ${\cal R}_{K e 3 / K2\pi}$,
${\cal R}_{K \mu 3
/ K2\pi}$ and
${\cal R}_{K \mu 3 / Ke3}$ are presented, based
on $K^\pm$ decays collected in a dedicated run in
2003 by the NA48/2 experiment at CERN. The results obtained are
$ {\cal R}_{K e 3 / K2\pi} = 0.2470\pm 0.0009 (stat)\pm 0.0004
(syst)$ and
$ {\cal R}_{K \mu 3 / K2\pi} = 0.1637\pm 0.0006 (stat)\pm 0.0003
(syst)$.
Using the PDG average for
the $K^\pm \rightarrow\pi^\pm \pi^0$ normalisation mode, both
values are
found to be larger
than the current values given by the Particle Data Book and lead to a
larger magnitude of the $|V_{us}|$ CKM element than previously
accepted. When combined with the latest Particle Data Book value
of $|V_{ud}|$,
the result is in agreement with unitarity of the CKM matrix.
In addition,
a new measured value of $ {\cal R}_{K \mu 3 / K2\pi} = 0.663\pm
0.003(stat)\pm
0.001(syst)$
is compared to the semi-empirical predictions based on the
latest form factor
measurements.
The Kmu3 form factors have been measured from a sample of $K_L$
decays in a dedicated run in 1999 by the NA48
experiment at CERN. Studying the Dalitz plot density, using the
linear form factor
approximation, a measurement was made of
$\lambda_+=26.7\pm0.6_{stat}\pm0.8_{sys}\times 10^-3$ and
$\lambda_0=11.7\pm0.7_{stat}\pm1.0_{sys}\times 10^-3$.
Measurements were also made
using the quadratic parameterisation, the pole parameterisation
and the dispersive
parameterisation. The results of all parameterisations will be
presented.
Primary author
Ms
Anne Dabrowski
(Department of Physics and Astronomy, Northwestern University)
