Speaker
Description
The KLOE-2 Collaboration continues the KLOE long-standing tradition of flavour physics precision measurements in the kaon sector with a new $K_S \to \pi e \nu$ branching fraction measurement.
Based on a sample of 300 million $K_S$ mesons produced in $\phi \to K_L K_S$ decays recorded by the KLOE experiment
at the DA$\Phi$NE $e^+e^-$ collider, the $K_S \to \pi e \nu$ signal selection exploits a boosted decision tree built with kinematic variables together with time-of-flight
measurements.
A fit to the reconstructed electron mass distribution provides the signal yield, then normalised to $K_S \to \pi^+ \pi^-$ decays. Data control samples of $K_L \to \pi e \nu$ decays are used to evaluate signal selection efficiencies.
The combination with our previous BR($K_S \to \pi e \nu$) measurement, based on an
independent data sample, allows the total precision to be improved by almost a factor of two, and a new derivation of $f_+(0)|V_{us}|$.
| In-person participation | Yes |
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