Chiral aspects of hadron structure

Chiral loop corrections for hadronic properties are considered in a constituent quark model. It is emphasized that the correct implementation of such corrections requires a sum over intermediate hadronic states. The leading non-analytic corrections are very important for baryon magnetic moments and explain the failure of the sum rule $(\mu_{\Sigma^{+}}+2\mu_{\Sigma^{-}})/\mu_{\Lambda}=-1$ predicted by the constituent quark model.Comment: 10 pages, latex, 2 ps figures, to appear in Phys. Lett.

Strange Hadronic Loops of the Proton: A Quark Model Calculation

Nontrivial $q \bar q$ sea effects have their origin in the low-$Q^2$ dynamics of strong QCD. We present here a quark model calculation of the contribution of $s \bar s$ pairs arising from a {\it complete} set of OZI-allowed strong $Y^*K^*$ hadronic loops to the net spin of the proton, to its charge radius, and to its magnetic moment. The calculation is performed in an ``unquenched quark model" which has been shown to preserve the spectroscopic successes of the naive quark model and to respect the OZI rule. We speculate that an extension of the calculation to the nonstrange sea will show that most of the ``missing spin" of the proton is in orbital angular momenta.Comment: revtex, 34 pages, 4 figure