Krishnanath Bandyopadhyay

INTERMEDIATE AND HIGH ENERGY BEHAVIOR OF THE SU(5)C MODEL

We have shown that the SU(5)C model cannot be distinguished from the Standard Model by measuring the spin-averaged cross-section and forward-backward asymmetry parameters in the processes near the Z peak and in the nonresonant sector. However, the e+e−→μ+μ− process can distinguish the SU(5)C model from the Standard Model in the nonresonant sector at the level of 2σ effect when MZ is around 100 GeV.

CP-VIOLATION IN A LEFT-RIGHT SYMMETRIC HORIZONTAL FLAVOUR CHIRAL MODEL

A horizontal symmetric model is studied in the light of spontaneous CP-violation. The left- and right-handed Kobayashi-Maskawa matrices are real and the CP-nonconservation occurs through horizontal gauge boson exchange. To be in accord with experiment, the relative phase between two Higgs vacuum expectation values must be rather small.

SPONTANEOUS CP VIOLATION IN A TWO GENERATION SU(2)L × SU(2)R × U(1)B − L × U(1)H MODEL

It is shown that spontaneous CP violation can occur in a two generation left–right symmetric horizontal model if there are two Higgs bi-doublets with the same horizontal hypercharge quantum number. The contributions to the KL − KS mass difference (Δm) and CP violating effects (∊, ∊′/∊, Dn) to the box and tree level diagrams are discussed to demonstrate that the experimental values of Δm and ∊ can be explained with suitable choice of the model parameters.

QUARK-MASS MATRICES IN THE TWO-GENERATION SU(2)L × SU(2)R × U(1)B−L × U(1)H GAUGE MODEL

We have studied the quark-mass matrices, Cabibbo mixing and CP violation in the two-generation SU(2)L × SU(2)R × U(I)B−L × U(1)H model. It is shown that the model leads to phenomenologically consistent quark-mass matrices but cannot accommodate CP violation in spite of the right-handed and horizontal gauge interactions. The absence of Cabibbo mixing for leptons is explained, but for the quark sector it is shown to be ≃0.21.

Strangeness changing baryon nonconservation in nonsupersymmetric theories

Abstract It is pointed out that a nonsupersymmetric standard SU(3) c × SU(2) L × U(1) Y model including an SU(3) H horizontal symmetry can explain strangeness nonconservation in proton decay. An operator analysis is carried out under very general assumptions, with certain Higgs fields present, to show that p → v K + , v K 0 K + , etc., strangeness changing decay modes are allowed while p → e + π 0 , v π + , etc., modes are suppressed to the lowest order in this model.