English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The branching fraction for the decay $K_S \to \pi e \nu$ has been measuredwith a sample of 300 million $K_S$ mesons produced in $\phi \to K_L K_S$ decaysrecorded by the KLOE experiment at the DA$\Phi$NE $e^+e^-$ collider. Signaldecays are selected by a boosted decision tree built with kinematic variablesand time-of-flight measurements. Data control samples of $K_L \to \pi e \nu$decays are used to evaluate signal selection efficiencies. A fit to thereconstructed electron mass distribution finds 49647$\pm$316 signal events.Normalising to the $K_S \to \pi^+\pi^-$ decay events the result for thebranching fraction is $\mathcal{B}(K_S \to \pi e \nu) = (7.211 \pm 0.046_{\rmstat} \pm 0.052_{\rm syst}) \times10^{-4}$. The combination with our previousmeasurement gives $\mathcal{B}(K_S \to \pi e \nu) = (7.153 \pm 0.037_{\rm stat}\pm 0.043_{\rm syst}) \times10^{-4}$. From this value we derive $f_+(0)|V_{us}|= 0.2170 \pm 0.009$.

Measurement of the $K_S \to \pi e \nu$ branching fraction with the KLOE experiment