arXiv subjects
Publications and source records attributed to T. W. Kephart.
We propose a standard model minimal extension with two lepton weak SU(2) doublets and a scalar singlet to explain the deviation of the measured anomalous magnetic moment of the muon from the standard model expectation. This scheme can be naturally motivated in string inspired models such as E_6 and AdS/CFT.
We present what we believe is the minimal three-family $AdS/CFT$ model compactified on a nonabelian orbifold $S^{5}/(Q\times Z_{3})$. Nontrivial irreps of the discrete nonabelian group $Q\times Z_{3}$ are identified with the $4$ of $SU(4)$ $R$ symmetry to break all supersymmetries, and the scalar content of the model is sufficient to break the gauge symmetry to the standard model. According to the conformality hypothesis the progenitor $SU(4)^3 \times SU(2)^{12}$ theory becomes conformally invariant at an infra-red fixed point of the renormalization group.
We construct the N=1 supergravity analog of the Green-Schwarz and heterotic superstring theories in 10D. We find the SO(8) theory previously found by compactification of 10D on $K3$. We also find eleven $G_2\times G_2$ theories, two with symmetric matter content. It is not obvious how ten of the $G_2\times G_2$ theories can be gotten from 10D.
The lepton family number violation $Z$ boson decay, $Z \to e^-e^-μ^+μ^+$ or $e^+e^+μ^-μ^-$, mediated by a dilepton, e.g. from an SU(15) theory, is calculated. The branching ratio of such exotic decay for allowed dilepton masses is found to be smaller than 10$^{-10}$.
We show that charged Eguchi-Hanson instantons provide a concrete and calculable new source of intrinsic Peccei-Quinn symmetry breaking by quantum gravity. The size of this breaking is shown to depend sensitively on the short distance details of a given theory, but is generically suppressed by fermion zero modes. Demanding that these gravitational effects not affet the axion solution to the strong CP problem, we find that at least two sets of quarks with differing Peccei-Quinn charges are required. In addition, these effects obviate the cosmological axion domain wall problem but leave unchanged problems associated with coherent axion oscillations.