الفهرس 
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Abstract
In this work we have given an analysis of the electric and chromoelectric dipole moments
of quarks and of the neutron arising in an extension of MSSM where there is an additional
vectorlike generation of quarks in the matter sector. The work presented here consists of
analytical results on ve di erent types of contributions to the electric and chromoelectric
dipole moments of quarks which include both non-supersymmetric as well as supersymmetric
loop contributions. In the non-supersymmetric sector we have contributions arising
from the exchanges of the W and Z bosons in the loops, while in the supersymmetric
sector we have exchanges involving charginos, neutralinos and the gluino in the loop. We
have also carried out a detailed numerical analysis of their relative contributions. Specifically
it is found that there exists strong interference e ects between the MSSM sector
and the vectorlike quark sector which can drastically change both the sign and the magnitude
of quark EDMs. The vectorlike generation brings in new sources of CP violation
which contribute to the quark EDMs. It is shown that in the absence of the cancellation
mechanism the experimental limit on the neutron EDM acts as a probe of new physics.
Speci cally, it is shown that assuming CP phases to be O(1), and with no cancellation
mechanism at work, one can probe scalar masses up to the PeV scale for the MSSM case.
Further, it is shown that the neutron EDM also acts as a probe of the extended MSSM
model which includes a vectorlike multiplet in its particle content. One expects signi cant
improvements in the sensitivity of the measurement of the neutron EDM in the future.
Thus, for instance, the nEDM Collaboration plans to measure the neutron EDM with an
accuracy of 9 1028 ecm which is more than an order of magnitude better than the
current limit. Such an improvement will allow one to extend the probe of new physics
even further [?]. For a recent analysis of the neutron EDM in a di erent class of models
see Ref. [?].
An important phenomenon in supersymmetric models with inclusion of explicit CP
violation relates to the mixing of CP even and CP odd Higgs bosons. We have investigated
the implication of a vectorlike quark multiplet on the CP even-CP odd mixing
within an extended MSSM model. As mentioned above, the sector brings with it new
sources of CP violation and our analysis shows that the vectorlike multiplet can generate
substantial CP even-CP odd Higgs mixing even in regions where the mixing from
the MSSM sector is small. We have investigated the dependence of the mixings on the
phases and nd that large mixings can occur in certain regions of the parameter space of
CP phases. The decays of the Higgs bosons into fermions are sensitive to new physics.
We have investigated these decays for the case of MSSM and for the case when one has
in addition a vectorlike multiplet. Further, for the latter case we have investigated the
dependence of the Higgs decays widths into fermions as a function of CP phases. These
decays show a sharp dependence on the phase of and on the phase of the trilinear cou.