WeakCoupling Currents and Symmetries of Strong Interactions
Abstract
The general isotopic properties of bilinear currents which will lead to the ∆S<=1 and ∆I=12 rules for weak decay processes are examined. The latter rule is reexpressed in terms of an equivalent mathematical statement which permits one to obtain the usual predictions in a simple manner. In general, when the strangenessconserving part of such a current is an isotopic vector, the strangenesschanging part can be a linear combination of I=12 and I=32 currents. The existence of an I=32 current could be established by experiments on the decays K>π+leptons, or on highenergy neutrino capture, ν+N>μ+Σ. Experiments on K_{e4} decays could test the bilinearity of the current. The assumption that the vector part of such a current, both strangeness changing and nonchanging, is quasiconserved (i.e., neglecting certain mass differences) in the presence of the strong interactions fixes the specific form of the current and further implies symmetries for the strong couplings. The various transformations which leave invariant a Yukawatype strong interaction as well as their associated currents are found. A new possible symmetry group of the strong interactions is examined: a 14 parameter group usually denoted as G2. In the presence of both π and K couplings, it is found that I=12 and 32 currents are quasiconserved when the strong Lagrangian has a 7dimensional rotational symmetry, while for the I=32 alone, the symmetry required is G2. In the presence of only πbaryon couplings, only I=12 currents can be quasiconserved. Certain predictions for the K_{e3} and K_{e4} modes of decay and for Σ^{}>n+e^{}+ν follow from the weak currents determined in this way.
 Publication:

Physical Review
 Pub Date:
 January 1961
 DOI:
 10.1103/PhysRev.121.324
 Bibcode:
 1961PhRv..121..324B