Skobeltsyn Institute of Nuclear Physics
Lomonosov Moscow State University

In a CPT-violating but Lorentz-invariant interacting quantum
field theory, elementary particles, such as leptons, quarks, Higgs,
their supersymmetric partners, and their antiparticles remain identical
even after the quantum corrections are taken into account. Thus the
CPT invariance is not the responsible symmetry for the equality of
the masses of an elementary particle and its antiparticle - it is
the Lorentz invariance. At the same time, if there exists a CPT-
violating interaction in Nature, for composite particles such as
$p- \\bar p$, $\\pi^+-\\pi^-$, $K0-\\bar K0$, etc., as well as for
bound states, such as hydrogen-antihydrogen, there are differences
in their masses, due to different bound-state energies, in their
total widths (life-times) and magnetic moments. Therefore, the
experimental measurements on the latter characteristics of composite
particles or bound systems would reveal the existence of a CPT-violating theory, although the theory is Lorentz invariant.