Phenomenological analysis of a topless left-right model.

Abstract

We reanalyze a topless left-right model due to Ma, after allowing flavor-changing neutral currents which are consistent with all the experimental limits coming from flavor-changing processes. The resulting model can naturally reproduce the observed values of {ital B}{sub {ital d}}{sup 0}{endash}{ital {bar B}} {sub {ital d}}{sup 0} mixing, where the original model had failed by 8 orders of magnitude. Thus, the model is viable from the viewpoint of low-energy phenomenology. In the case of {ital Z}{sup 0} physics, however, we see that the model makes distinctive predictions for some of the {ital Z}{sup 0}{r arrow}{ital f{bar f}} partial widths due to the nonstandard couplings of the fermion {ital f}. The recent measurements of these partial widths from CERN LEP seem to clearly rule out this model. Indeed the precision measurement of the {ital Z}{sup 0}{r arrow}{ital b{bar b}} partial width along with the known properties of {ital b} decay seems to rule out any topless model.