Jul 6 – 13, 2022
Bologna, Italy
Europe/Rome timezone

A new $K_S \to \pi e \nu$ branching fraction measurement from KLOE-2

Jul 7, 2022, 6:08 PM
Room 9 (Indaco)

Room 9 (Indaco)

Parallel Talk Quark and Lepton Flavour Physics Quark and Lepton Flavour Physics


Antonio Passeri (Istituto Nazionale di Fisica Nucleare)


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
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

Primary author

Antonio Passeri (Istituto Nazionale di Fisica Nucleare)

Presentation materials