## PROBING SUPERSYMMETRIC GRAND UNIFICATION WITH CP AND FLAVOR VIOLATIONS

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##### Date

2006-08-24##### Author

Rastogi, Parul

##### Advisor

Pati, Jogesh C

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A major part of my thesis is devoted to explore
certain issues of CP and flavor violations in conjunction with
those of fermion masses and neutrino oscillations in the context
of supersymmetric grand unification. An attempt is made to present
a {\it unified description} of four phenomena: (i) fermion masses
and mixings, (ii) neutrino oscillations, (iii) CP non conservation
and (iv) flavor violations in both the quark and the lepton
sectors, in accord with observations, within a single predictive
framework based on supersymmetric SO(10) or an effective $G(224)$
symmetry.
Including standard model and supersymmetric contributions, it is
shown that the framework correctly accounts for $\Delta m_K,~
\Delta m_{B_d}, ~ S(B_d\to J/\psi K_s)$ {\it and } $\epsilon_K$.
While SUSY-contribution is small ($\lsim $ few\%) for the first
three quantities, that to $\epsilon_K$ is found to be sizable
($\sim$ 20-25\%) and negative relative to the standard model as
desired. The model predicts $S(B_d\to \phi K_s)$ to be in the
range +(0.65--0.73), close to the standard model prediction; it
yields $Re(\epsilon'/\epsilon)_{SUSY}\approx +(4-14)\times
10^{-4}$. The model also predicts that the electric dipole moments
of the neutron and the electron should be discovered with
improvements in current limits by factors of 10 to 100.
Assuming SUSY-messenger scale to be higher than the GUT scale, it
is found that post-GUT physics, which has commonly been neglected
in the literature, contributes significantly to CP and flavor
violating processes. Including such contributions, the model
predicts enhanced rates for $\mu\to e\gamma, ~\tau\to \mu\gamma$
and $\mu N\to e N$ which should be seen in forthcoming
experiments.
A comparison of two promising SO(10) models, one with hierarchical
fermion mass matrices (by Babu, Pati and Wilczek), and the other
with lop-sided mass matrices (by Albright and Barr) is done, as
regards their predictions regarding CP and flavor violations.
Crucial tests are noted which would sharply distinguish between
the models.
Envisaging string origin of the effective unification symmetry in
4D, the second part of my thesis will explore the issue of gauge
coupling unification at the string scale when supersymmetric
standard model and an extension is embedded in an effective G(224)
or $G(214)\equiv SU(2)_L\times U(1)_{I_{3R}}\times SU(4)^c$
symmetry near the GUT scale.

University of Maryland, College Park, MD 20742-7011 (301)314-1328.

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