[π-π+] atom => π0 + π0
The goal is to measure the
[π-π+] atom lifetime
of about 3 fs (ground state) with 10% precision.
The goal is to measure the
[π-π+] atom lifetime
of about 3 fs (ground state) with 10% precision.
This measurement will provide - in a model independent
way - a 5% precise value for the S-wave
isoscalar minus isotensor pion scattering lengths difference
|a0−a2|.
Low energy QCD in the framework of Chiral Perturbation Theory (ChPT)
predicts nowadays scattering lengths with very high accuracy
of less than 2%. Therefore, such a measurement will
check sensitively the understanding of chiral symmetry breaking
in QCD by giving an indication about the size of the
quark condensate, an order parameter of QCD.
ChPT predictions for the scattering lengths lead to a
[π-π+] atom lifetime of
(2.9±0.1) fs.