Speaker
Dr
Valeriy Yazkov
(Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University)
Description
Theory, using Low Energy QCD, calculated with high precision the $\pi\pi$ and $\pi K$ scattering length. Because these calculations are
using the chiral symmetry that describe quarks, gluons, and the QCD
vacuum property, the experimental check of these predictions is important. To check the theoretical calculations for the process
including also $s$ quarks we must measure the $\pi K$ atom lifetime
that is connected to the $\pi K$ scattering lengths by a precise
relation. The results of the search for hydrogen-like atoms consisting
of $\pi^-K^+$ and $\pi^+K-$ mesons are presented. Evidence for $\pi K$
atoms production, using a 24 GeV/c protons beam from CERN PS
interacting with a nickel target, is reported here. From the analysis
of Coulomb final state interaction $\pi K$ pairs was evaluated the
number of produced $\pi K$ atoms $N_A=653 \pm 42$ together with the
value of the $\pi K$ pairs from atoms that breakup in the same target
$N_a=178 \pm 49$. Using these results the analysis yields to a first
value for the $\pi K$ atom lifetime of $t=2.5^{+3.0}_{-1.8}$ fs and a
first model-independent measurement of the S-wave isospin-odd $\pi K$
scattering length $|a0-| = 1/3 |a_{1/2} - a_{3/2}| =
0.11^{+0.09}_{-0.04}$ $1/M_{\pi}$ (the I in $a_I$ stands for isospin).
Primary author
Dr
Valeriy Yazkov
(Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University)
