The influence of c.m. motion and chiral symmetry on masses and electroweak parameters of hadrons in the bag model

A thorough numerical analysis of the two major improvements of the original MIT bag model is presented. It is shown that the c.m. motion correction alone gives a good fit to hadron masses (including the qq? pion). The chiral-pion-cloud correction taken at full strength spoils this good agreement. If the quark-pion coupling is lowered by about 40% a reasonable fit is obtained again, while the electroweak parameters are well reproduced by both fits.