Low Scale Theories: Light Neutrinos and Unification of Gauge Couplings

Mechanism for generation of suppressed neutrino masses, within low scale theories, is considered. The mechanism do not have extradimensional nature and is realized through extended $SU(2)_L$ scalar multiplets. Latters, in some cases, are also crucial for successful low scale unification.Comment: Talk given at 9th Internation Conference on Supersymmetry and Unification of Fundamental Interactions (SUSY'01), Dubna, Russia, June 11-17, 200

Three Family SU(5) GUT and Inverted Neutrino Mass Hierarchy

Supersymmetric SU(5) GUT augmented with anomaly free U(1)_F flavor symmetry is presented. Very economical field content and U(1)_F charge assignment are obtained by specific construction. In particular, three families of 10+5* chiral matter, along the SU(5) singlet states (some of which serve as right handed neutrinos) are obtained. Appealing texture zero Yukawa matrices provide natural understanding of hierarchies between charged fermion masses and mixings. The model predicts inverted hierarchical neutrino mass scenario with interesting implications.Comment: 15 pages LaTex, 2 figure

New Flavor U(1)_F Symmetry for SUSY SU(5)

Within supersymmetric SU(5) Grand Unified Theory, we present several new scenarios with anomaly free flavor symmetry U(1)_F. Within each scenario, a variety of cases offer many possibilities for phenomenologically interesting model building. We present three concrete and economical models with anomaly free U(1)_F leading to natural understanding of observed hierarchies between charged fermion masses and CKM mixing angles.Comment: As appear in PL

Anomalous U(1): Solving Various Puzzles Of MSSM And SU(5) GUT

We discuss how an anomalous U(1) symmetry when appended to MSSM and SUSY GUTs [e.g. SU(5)] can help overcome a variety of puzzles related to charged fermion masses and mixings, flavor changing processes, proton decay and neutrino oscillations. Proton lifetime for SU(5) GUT, in particular, is predicted in a range accessible to the ongoing or planned searches.Comment: Presented at NOON2001 Workshop, Kashiwa, Japan, 5-8 Dec. 200