r.e. Heavy baryon decay, here is a feynmann diagram showing a delta baryon decaying into a proton and pion. The down + anti-down quark pair that appears in the

r.e. Heavy baryon decay, here is a feynmann diagram showing a delta baryon decaying into a proton and pion. The down + anti-down quark pair that appears in the middle of the diagram are virtual particles: https://ned.ipac.caltech.edu/level5/Cottingham/Figures/figure1_3.jpeg https://ned.ipac.caltech.edu/level5/Cottingham/Figures/figur...