  From the study of a sample of about 62.3 million well reconstructed K0S
decays recorded by the KLOE detector at the DAFNE accelerator in Frascati, the
lifetimes of K0S mesons parallel and antiparallel to the direction of motion of
the Earth with respect to the Cosmic Microwave Background reference frame have
been studied. No difference has been found, and a limit on a possible asymmetry
of the lifetime with respect to the CMB has been set at 95% C.L.: A < 0.98 x
10-3. This is presently the best experimental limit on such quantity, and it is
smaller of the speed, expressed in natural units, of the Solar System with
respect to the CMB. The present limit might constrain possible
Lorentz-violating anisotropical theories.
