Electroweak transition

Some people had proposed that the preference of left-handed amino acids may be related to electroweak interactions which stabilize very slightly the left-handed amino acids. Indeed, bifurcations are very sensitive to very small differences of energy. If the transition is going very slowly over the years, then even such very small differences in energy will introduce a slight effect in favor of one of the two amino acids. 

One might think that the electroweak theory can explain the baryon asymmetry. The 3rd out-of-equilibrium condition is met if the electroweak phase transition is of strongly 1st order. In this case the phase transition proceeds via bubble formation of the broken electroweak phase. Quarks propagating across the bubble wall may be reflected back, thereby producing the baryon asymmetry [17]. 

The electroweak scenario is now regarded very unlikely to be true [18]. Two main reasons are (1) light Higgs mass needed for the 1st order phase transition is now experimentally excluded, (2) even if the Higgs mass bound is ignored, the estimated baryon to the photon ratio is too small by more than 10 orders. 

Had this process proceeded unchecked it would have by-passed several important stages in cosmic evolution between t = 10 and Is, such as baryogenesis, electroweak symmetry breaking, combination of free quarks to form hadrons and interconversion between protons and neutrons. Not to interrupt this orderly evolution it would therefore be useful to have the phase transition postponed for a while. Many phase transitions are indeed known to be delayed by the phenomenon of supercooling. Why not this one ... 

There are many other approaches to the detection of the electroweak-induced parity violating transitions. One of the most accurate involves looking for the highly forbidden Ml transitions 65i/2 75i/2 hi cesium... 

The Appendix has been much enlarged. It now contains a more detailed specification of the Feynman rules for electroweak theory and QCD, and a discussion of the relations between [Pg.532]

F(B° /i+ )/r(B° all) < 7 x 10. One cannot isolate flavor-changing neutral current (FCNC) effects in non leptonic decays. For exampleFthe FCNC transition s d + (u- -u) is equivalent to the charged-current transition if —> a -I- ( + d). Tests for FCNC are therefore limited to hadron decays into lepton pairs. Such decays are e3q>ected only in second-order in the electroweak coupling in the Standard Model. 

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