Phenomenology of harmless family gauge bosons to $K^0-\bar{K}^0$ mixing

Abstract

When we try to consider family gauge bosons with a lower energy scale, a major obstacle is constraints from the observed [Formula: see text] mixings [Formula: see text]. Against such a conventional view, we point out that, in a U(3) family gauge boson model, the bosons are harmless to any [Formula: see text] mixings independently of explicit values of the family mixings, if masses Mij of the gauge bosons [Formula: see text] (i, j are family indexes) satisfy a relation [Formula: see text]. If such the case can be realized together with an inverted mass hierarchy [Formula: see text], we can consider family gauge bosons with a considerably lower scale, so that we can expect rich signs for family gauge bosons in a TeV scale.