Relativistic harmonic-oscillator quark model andK→ππdecays

Abstract
It is shown how the theoretical description of Kππ decays depends on the particular quark model. The relativistic MIT bag model is compared with the nonrelativistic harmonic-oscillator model and with two relativistically corrected versions of the harmonic-oscillator model. The relativistic effects in quark dynamics seem to be crucial for the understanding of Kππ transitions.