Abstract
The sea-quark content of baryons (such as s^^-s, c^^-s, b^^-b・・・) is calculated by a combined use of the QCD trace anomary and a chiral quark model. The result is applied to the examination of the explicit symmetry breaking in baryons (such as the π-N and K-N sigma terms), the intrinsic heavy quqrks in baryons, and the Higgs-baryon coupling constants. We find that (i) the large s^^-s content is unnecessary to reproduce the empirical value of the sigma term, (ii) the probability of finding charm in the nucleon os about 0.5%, which is relevant to the charm structure function of the nucleon at large x and also to the chram production in proton-nucleous collisions at large Feynman x_F, and (iii) both strange and heavy quarks are equally important for the Higgs-nucleon coupling. Small but non-negligible OZI-violation in baryons due to the axial anomaly plays a key role in all the above quantites. The sea-quark content of the pion and the kaon and the color-sextet quarkbcontent in nucleon are also discussed.
