Measurement of the Ks into 2 photons ratio using a pure Ks beam

A precise measurement of the Ks into two photons
decay rate is an
important test of Chiral Perturbation Theory predictions.
This amplitude has been evaluated
at the leading order of ChPT, O(p4),
providing the estimate of the corresponding branching
ratio,
2.1x 10^(-6), with a few percent
precision.
The last precise determination of this
ratio of 2.71x10^(-6), with a total uncertainty below
3%, comes from
NA48. The last mentioned result differs from ChPT
prediction of about 30%, indicating possible
contributions from higher order corrections.
From 2 billion phi mesons
collected with KLOE at DAFNE,
we have measured this ratio
with a 5.3% statistical uncertainty and a 2%
systematic error.
We obtain a BR result which deviates by 3 sigma's
from the previous
best determination but confirm ChPT prediction completely
neglecting possible higher order corrections.

Autorentext

Matteo Martini was born in frascati (Italy) on 12thOctober 1980.He works as researcher in Particle Physics at "Italian Instituteof Nuclear Physics".He works on data analysis of rare kaon decays.He got the phd in 2008 discussing the measurement of brancingratio of Ks into two photons.He is involved in the project and realization of detectors.

Klappentext

A precise measurement of the Ks into two photonsdecay rate is animportant test of Chiral Perturbation Theory predictions.This amplitude has been evaluated at the leading order of ChPT, O(p4), providing the estimate of the corresponding branchingratio, 2.1x 10^(-6), with a few percent precision. The last precise determination of this ratio of 2.71x10^(-6), with a total uncertainty below3%, comes fromNA48. The last mentioned result differs from ChPT prediction of about 30%, indicating possible contributions from higher order corrections.From 2 billion phi mesonscollected with KLOE at DAFNE, we have measured this ratiowith a 5.3% statistical uncertainty and a 2%systematic error. We obtain a BR result which deviates by 3 sigma's from the previousbest determination but confirm ChPT prediction completelyneglecting possible higher order corrections.