We present a precise measurement of the ratio RK=Γ(K→eν(γ))/Γ(K→μν(γ)) and a study of the radiative process K→eνγ, performed with the KLOE detector. The results are based on data collected at the ...Frascati e+e− collider DAΦNE for an integrated luminosity of 2.2 fb−1. We find RK=(2.493±0.025stat±0.019syst)×10−5, in agreement with the Standard Model expectation. This result is used to improve constraints on parameters of the Minimal Supersymmetric Standard Model with lepton flavor violation. We also measured the differential decay rate dΓ(K→eνγ)/dEγ for photon energies 10<Eγ< 250 MeV. Results are compared with predictions from theory.
Using a large sample of pure, slow, short lived K0 mesons collected with KLOE detector at DAΦNE, we have measured the KS lifetime. From a fit to the proper time distribution we find ...τ(KS)=(89.562±0.029stat±0.043syst) ps. This is the most precise measurement to date of the short lived K0 meson lifetime, in good agreement with the world average derived from previous measurements. We observe no dependence of the lifetime on the direction of the KS in galactic coordinates.
We present a measurement of the ratio R=Γ(K
0
e3γ
;E
*
γ
> 30 MeV, θ
*
γ
>20
°
)/Γ(K
0
e3
) and a first measurement of the direct emission contribution in semileptonic K
L
decays. The measurement was ...performed at the DA NE φ factory by selecting φ→K
L
K
S
decays with the KLOE detector. We use 328 pb
-1
of data, corresponding to about 3.5 million K
0
e3
events and about 9000 K
0
e3γ
radiative events. Our result is R=(924±23
stat
±16
syst
)×10
-5
for the branching ratio and 〈X〉=-2.3±1.3
stat
±1.4
syst
for the effective strength parameter describing direct emission.
We have measured the cross section σ(e+e−→π+π−γ(γ)) at DAΦNE, the Frascati ϕ-factory, using events with initial state radiation photons emitted at small angle and inclusive of final state radiation. ...We present the analysis of a new data set corresponding to an integrated luminosity of 240 pb−1. We have achieved a reduced systematic uncertainty with respect to previously published KLOE results. From the cross section we obtain the pion form factor and the contribution to the muon magnetic anomaly from two-pion states in the mass range 0.592<Mππ<0.975 GeV. For the latter we find Δππaμ=(387.2±0.5stat±2.4exp±2.3th)×10−10.
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