Amitava Raychaudhuri

Aspects of CP violation in supersymmetric theories

We give a comprehensive study of CP-violating effects in low-energy softly broken supersymmetric theories. We find that gluino exchange contributions to CP violation arising from the Kobayashi-Maskawa mixing matrix may provide indirect evidence of supersymmetry at low energy. Indeed, we point out two important departures from the predictions of the standard model: (i) in the kaon system, the experimental value of the var epsilon-parameter cannot be reconciled with a large B-lifetime (τB>10−12s) and light top quark (mtless, approximate50GeV) in the context of the usual three-generation standard model; this is no longer true when the additional supersymmetry contributions to CP violation are included; (ii) in the beon system, the presence of supersymmetry enhances Image mixing as well as off-shell and on-shell CP-violating phenomena making more likely an experimental detection of some of the effects. On the other hand, the electric dipole moment of the neutron due to the Kobayashi-Maskawa phase is still very small and var epsilon′/var epsilon continues to be consistent with the experimental bounds.

Super Kobayashi-Maskawa CP-violation

We argue that in the minimal SUSY extension of the standard model, CP-violation cannot be explained through SUSY phase alone. But SUSY graphs, especially with gluinos, can make important contributions to CP-violation through the Kobayashi-Maskawa phase.

Bottom Lifetime, Top Mass And Cp Violation In Supersymmetric Theories.

We demonstrate the compatibility of a light top quark, a long-lived bottom quark and Kobayashi-Maskawa CP-violation in supersymmetric theories without invoking for example the existence of a fourth generation. In certain cases, constraints on the s-particle spectrum are unavoidable and testable.

Gluino penguins and ε′/ε

We calculate the penguin diagrams involving gluinos and discuss their implications on e′/e. The dominant contribution originates in the Kobayashi-Maskawa phase. Fixing this phase from the e parameter, we find a smaller value of e′/e; than in the non-supersymmetric case alone.

Demonic constraints on supergravity models

Abstract We consider renormalization group scaling of the CP -violating phases of softly broken supersymmetry. We show that unless A ( M X is real or close to zero, these phases are naturally large in conflict with the experimental bound on the dipole electric moment of the neutron (DEMON) d n . We also show that for a large class of supergravity models d n ≅10 −28 e cm (and could even be as large as 10 −27 e cm), a prediction that is two orders of magnitude higher than the standard model Kobayashi-Maskawa prediction.

Probing exotic leptons through oblique parameters

We show that the oblique electroweak parameter S receives a small positive contribution when sterile neutrinos or vector doublet leptons mix with their sequential counterparts. For vector triplet leptons the contribution is of similar size and is positive but for a small region in parameter space.

ΔS=2 processes in ETC models with a left-right symmetric electroweak sector

TheKL-KS mass difference in a dynamically broken gauge theory based on aSU(2)L⊗SU(2)R⊗U(1)B-L electroweak sector with manifest left-right symmetry and low right handed mass scale is analysed. We find that consistency with the observedKL-KS mass difference requires a smaller suppression factor than the corresponding quantity in a similar theory based on the standard electroweak sector. The required suppression may be accommodated in this model by reasonable choices of the adjustable parameters of the theory.