Amplitude zeroes‐tests of the magnetic moment of the W boson and the quarks

We consider the general phenomenon of amplitude zeroes, first discovered in the process du→W−γ. The effect of the quarks having an anomalous magnetic moment on the observed dū→W−γ (pp→ W−γX) is studied. It is found that for small values (≤10−3) of the quark anomaly [a≡(g‐2)/2] the distributions are practically unaffected provide us with a way of obtaining an upper bound for the anomalous magnetic moment of the W bosons. Using spin‐O particles, we investigate the circumstances for amplitude zeroes to occur in the physical region and, as well, their location in phase space. Furthermore, we ask whether or not these zeroes persist in higher order. The zeroes persist for internal line radiation and for radiation from internal bubbles. However, when we consiser the 1‐loop correction to the scalar three‐point function (with a photon attached in all possible ways), it is shown, by an explicit calculation, that amplitude zeroes do not persist in general.