Strong and weakCPin a model with a new gauged U(1) symmetry

Abstract

We discuss a natural solution to the strong CP problem with spontaneous CP breaking in the context of SUci 3 ) X SULi2) XU,( 1) XU,,,il) with two vectorlike quarks. The gauged U,,,(l) symmetry is imposed such that eremains zero at the tree level when CP and U,,,il) are broken by singlet Higgs scalars. Flavor-changing neutral currents at the tree level are naturally suppressed because only singlet Higgs scalars are introduced. In order to agree with the experimental measurement of E and E ' / E , we find that the CP-breaking scale and the masses of the new quarks are less than 2.0 TeV and 530 GeV, respectively.

Cabibbo mixing and the search forCPviolation in the aspon model

“…Using Eq. (35) of [6] and requiring that U(1) ′ break down above the electroweak scale (i.e., κ ≥ 250 GeV), we find x 2 ≥ 3 × 10 −5 . With x 2 this large, box diagrams with χ exchange (in addition to conventional box diagrams) can contribute significantly to the neutral kaon mass difference.…”

“…With x 2 this large, box diagrams with χ exchange (in addition to conventional box diagrams) can contribute significantly to the neutral kaon mass difference. Unlike a superweak model [9], our description of neutral kaons yields a non-zero value of |ǫ ′ /ǫ| bounded above by 2 × 10 −3 [6].…”

“…In this paper, we explore CP -violation in the context of an 'Aspon model' [5][6][7][8] wherein the violation of CP is spontaneous. In particular, we add to the 3-family standard model a vector-like SU(2) doublet of quarks (U, D) L ⊕ (U, D) R together with two complex SU (2) singlet scalars χ 1,2 .…”

Outcome from spontaneousCPviolation forBdecays

“…This is important because, as a consequence, aspon exchange dominates the imaginary part of M 12 (K). This allowed upper limits on the aspon mass (and the CP violating scale) to be arrived at in the original aspon papers [4,5]. The aspon mass was made sufficiently small so that the K 0 -K 0 mixing phase compensated the smallness of the phase in the decay amplitude for s → uūd (W exchange).…”

“…(10-12), g is the coupling constant for electroweak SU(2), g A is the coupling constant for the new gauged U(1), M A is the mass of the aspon, and the x i are given in the notation of [5] as x i = F i /M. The expression for K 0 -K 0 mixing uses the fact that |V * cd V cs m c | ≫ |V * td V ts m t | and hence amongst possible internal quarks the charm quark dominates the top quark, unlike the case for B 0 -B 0 mixing where the top quark dominates.…”