Speaker: Valeri IAZKOV
Title
Lifetime measurement of atoms consisting of $\pi^{+}$ and $\pi^{-}$ mesons
Abstract
The lifetime measurement of $\pi^{+}$ $\pi^{-}$ atoms ($A_{2{\pi}}$) with 10\% precision provides the in a model independent way the difference between the S-wave $\pi\pi$ scattering lengths for isospin 0 and 2, $|a_0 -a_2|$, with 5\% accuracy. The scattering lengths $a_{0}$ and $a_{2}$ were calculated by the Chiral Perturbation Theory (ChPT) with a precision better than 2.5\%, Therefore, such a measurement will be a sensitive check of the understanding of chiral symmetry breaking of QCD by giving an indication about the value of the quark condensate, an order parameter of QCD. The method of observation and lifetime measurement of $A_{2\pi}$ are discussed. Data on the $A_{2\pi}$ production on Pt, Ni and Ti targets and preliminary results on the lifetime measurement are presented.

Slides