Otto C. W. Kong

A simple phenomenological parametrization of supersymmetry without R-parity

Abstract We present a parametrization of the supersymmetric standard model without R-parity that permits efficient phenomenological analyses of the full model without a priori assumptions. Under the parametrization, which is characterized by a single vacuum expectation value for the scalar components of the Y =−1/2 superfields, the expressions for tree-level mass matrices are quite simple. They do not involve the trilinear R-parity violating couplings; however, the bilinear μ i terms do enter and cannot be set to zero without additional assumptions. We set up a framework for doing phenomenology and show some illustrative results for fermion mass matrices and related bounds on parameters. We find in particular that large values of tan β can suppress R-parity violating effects, substantially weakening experimental constraints.

On neutrino masses and mixings from extra dimensions

Abstract In the framework of a Kaluza-Klein type theory with the Standard Model fields localized on a 4-dimensional section while gravity propagates in a full 4+ δ -dimensional space-time, we examine a mechanism of naturally small neutrino mass generation through couplings of the Standard Model singlet fermion(s) living also in the full space-time. A numerical study is carried out on the charged current universality constraint from the ratio of pion decay partial widths. The bounds obtained on the fundamental mass scale could be stringent.

Neutrino oscillations and flavor structure of supersymmetry without R-parity

Focusing on a simple three neutrino oscillation scenario motivated by the recent super-Kamiokande result, we discuss both tree-level and one-loop contributions to neutrino masses in supersymmetry without R-parity, aiming at discerning the flavor structure issues of the theory. The single-vev parametrization framework, which allows the first consistent treatment of the bilinear and trilinear R-parity violating terms, and hence the tree and one-loop contributions, without any assumption on the nature of R-parity violation. Though the very small neutrino masses imply stringent suppressions of the relevant R-parity violating couplings, we show that there is still room for understanding the suppressions as a simple consequence of the general flavor hierarchy.

Pseudo-Dirac neutrinos

Abstract We propose a scheme in which a pseudo-Dirac structure for three family of light neutrinos is generated naturally. An extended Higgs sector with a majoron is used for the generation of the leptonic number violating neutrino Majorana mass. The resultant neutrino mass matrix could easily fit all available experimental data. We discuss relevant constraints on the scales involved for the model to be phenomenologically viable.

Supersymmetry without R parity: Constraints from leptonic phenomenology

R-parity conservation is an ad hoc assumption in the most popular version of the supersymmetric standard model. Most studies of models which do allow for R-parity violation have been restricted to various limiting scenarios. The single-VEV parametrization used in this paper provides a workable framework to analyze phenomenology of the most general theory of SUSY without R parity. We perform a comprehensive study of leptonic phenomenology at the tree level. Experimental constraints on various processes are studied individually and then combined to yield regions of admissible parameter space. In particular, we show that large R-parity violating bilinear couplings are not ruled out, especially for large tan {beta}. (c) 2000 The American Physical Society.

Neutrino oscillations from supersymmetry without R-parity: Its implications on the flavor structure of the theory

We discuss here some flavor structure aspects of the complete theory of supersymmetry without R-parity addressed from the perspective of fitting neutrino oscillation data based on the recent Super-Kamiokande result. The single-VEV parameterization of supersymmetry without R-parity is first reviewed, illustrating some important features not generally appreciated. For the flavor structure discussions, a naive, flavor-model-independent, analysis is presented, from which a few interesting things can be learned.

Lepton–chargino mixing and R-parity violating SUSY

We present a study of charged lepton mass matrix diagonalization in R-parity violating SUSY. The case in which the bilinear couplings μi have large values is given special attention.

Could the τ be substantially different from e and μ in the supersymmetric standard model

R-parity stands as an ad hoc assumption in the most popular version of the supersymmetric standard model. More than fifteen years studies of R-parity violations have been restricted to various limiting scenarios. We illustrate how the single-VEV parametrization provides a workable framework to analyze the phenomenology of the complete theory of supersymmetry without R-parity. In our comprehensive study of various aspects of the resulting leptonic phenomenology at tree-level, we find that the physical τ lepton could actually bear substantial gaugino and higgsino components, making it very different from the e and the μ.

Two-higgs-doublet-models and radiative CP violation

We discuss the feasibility of spontaneous CP violation being induced by radiative corrections in 2HDM’s. Specifically, we analyze the cases of gaugino/higgsino effect on MSSM, and a new model with an extra exotic quark doublet. The new model, while demonstrating well the Georgi-Pais theorem, is also expected to be phenomenlogically interesting.

R-Parity “Я” us Rochester

R-parity violating terms in the minimal supersymmetric extension of the Standard Model are studied within a parametrization characterized by a single vacuum expectation value for the scalar components of the Y=−1/2 superfields. The benefits of this efficient parametrization are that it enables phenomenological analyses of R-parity violation without a priori assumptions (such as setting most R-parity violating terms to zero in an ad hoc way). The tree-level fermionic mass eigenstates are derived and shown to be particularly simple in this scheme, involving only the bilinear μi R-parity violating terms. Suprisingly large values of these μi are consistent with the experimental constraints. This is outlined.