Extended time-reversal operator and the symmetries of the hyperon-nucleon interaction

An extended time-reversal operator incorporating charge conjugation in the flavor SU3 space is introduced in order to study the spin-flavor structure of the hyperon-nucleon interaction. Particle-hole conjugation in terms of this extended time reversal is found to be useful to characterize time-reversal odd components for the space-spin part of the hyperon-nucleon interaction, which yield non-zero contributions to the exchange Feynman diagram or to the transition amplitude between Lambda N and Sigma N systems when the flavor symmetry breaking is properly introduced. Some selection rules are also given for the spin-flavor factors appearing in the quark-model potentials of the hyperon-nucleon interaction.