On A Classification of Mesons
  We give a mass formula for computing the mass spectrum of mesons. By this formula we show that there are many mesons with their masses corresponding to a prime number. In particular we show that all strange mesons are with their masses corresponding to a prime number. With these prime numbers indexing the mesons we give a classification of mesons. We set up a knot model of mesons to derive this mass formula. In this knot model mesons and their anti-particles are modeled by knots and their mirror images respectively. Then the amphichiral knots which are equivalent to their mirror images are used to model mesons which are identical with their anti-particles. With this knot model we show that there is a periodic phenomenon in the classification of mesons such that the starting nonet and the ending nonet are nonets of pseudoscalar mesons with the $\pi$ meson modeled by an amphichiral knot. From this periodic phenomenon we give a theoretical argument for the existence of charm-anticharm mesons. 
Sze Kui Ng