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(S{sub 3}){sup 3} theories of flavor

Description: The author presents a supersymmetric theory of flavor based on the discrete flavor group (S{sub 3}){sup 3}. The model can account for the masses and mixing angles of the standard model, while maintaining sufficient sfermion degeneracy to evade the supersymmetric flavor problem. The author demonstrates that the model has a viable phenomenology and makes one very striking prediction: the nucleon decays predominantly to Kl where l is a first generation lepton. He shows that the modes n {yields} K{sup 0}{bar {nu}}{sub e}, p {yields} K{sup +}{bar {nu}}{sub e}, and p {yields} K{sup 0}e{sup +} occur at comparable rates, and could well be discovered simultaneously at the SuperKamiokande experiment.
Date: July 1, 1996
Creator: Carone, C.D.
Partner: UNT Libraries Government Documents Department

Light U(1) gauge boson coupled to baryon number

Description: The authors discuss the phenomenology of a light U(1) gauge boson, {gamma}{sub B}, that couples only to baryon number. Gauging baryon number at high energies can prevent dangerous baryon-number violating operators that may be generated by Planck scale physics. However, they assume at low energies that the new U(1) gauge symmetry is spontaneously broken and that the {gamma}{sub B} mass m{sub B} is smaller than m{sub z}. They show for m{sub {Upsilon}} < m{sub B} < m{sub z} that the {gamma}B coupling {alpha}{sub B} can be as large as {approximately} 0.1 without conflicting with the current experimental constraints. The authors argue that {alpha}{sub B} {approximately} 0.1 is large enough to produce visible collider signatures and that evidence for the {gamma}{sub B} could be hidden in existing LEP data. They show that there are realistic models in which mixing between the {gamma}{sub B} and the electroweak gauge bosons occurs only as a radiative effect and does not lead to conflict with precision electroweak measurements. Such mixing may nevertheless provide a leptonic signal for models of this type at an upgraded Tevatron.
Date: June 1, 1995
Creator: Carone, C.D. & Murayama, Hitoshi
Partner: UNT Libraries Government Documents Department

A hexagonal theory of flavor

Description: The authors construct a supersymmetric theory of flavor based on the discrete gauge group (D{sub 6}){sup 2}, where D{sub 6} describes the symmetry of a regular hexagon under proper rotations in three dimensions. The representation structure of the group allows one to distinguish the third from the lighter two generations of matter fields, so that in the symmetry limit only the top quark Yukawa coupling is allowed and scalar superpartners of the first two generations are degenerate. Light fermion Yukawa couplings arise from a sequential breaking of the flavor symmetry, and supersymmetric flavor-changing processes remain adequately suppressed. They contrast the model with others based on non-Abelian discrete gauge symmetries described in the literature, and discuss the challenges in constructing more minimal flavor models based on this approach.
Date: May 1, 1999
Creator: Carone, C.D. & Lebed, R.F.
Partner: UNT Libraries Government Documents Department

U(2) flavor physics without U(2) symmetry

Description: The authors present a model of fermion masses based on a minimal, non-Abelian discrete symmetry that reproduces the Yukawa matrices usually associated with U(2) theories of flavor. Mass and mixing angle relations that follow from the simple form of the quark and charged lepton Yukawa textures are therefore common to both theories. They show that the differing representation structure of the horizontal symmetry allows for new solutions to the solar and atmospheric neutrino problems that do not involve modification of the original charged fermion Yukawa textures, or the introduction of sterile neutrinos.
Date: October 1, 1999
Creator: Aranda, A.; Carone, C.D. & Lebed, R.F.
Partner: UNT Libraries Government Documents Department

Maximal neutrino mixing from a minimal flavor symmetry

Description: The authors study a number of models, based on a non-Abelian discrete group, that successfully reproduce the simple and predictive Yukawa textures usually associated with U(2) theories of flavor. These models allow for solutions to the solar and atmospheric neutrino problems that do not require altering successful predictions for the charged fermions or introducing sterile neutrinos. Although Yukawa matrices are hierarchical in the models they consider, the mixing between second- and third-generation neutrinos is naturally large. They first present a quantitative analysis of a minimal model proposed in earlier work, consisting of a global fit to fermion masses and mixing angles, including the most important renormalization group effects. They then propose two new variant models: The first reproduces all important features of the SU(5) x U(2) unified theory with neither SU(5) nor U(2). The second demonstrates that discrete subgroups of SU(2) can be used in constructing viable supersymmetric theories of flavor without scalar universality even though SU(2) by itself cannot.
Date: February 1, 2000
Creator: Aranda, A.; Carone, C.D. & Lebed, R.F.
Partner: UNT Libraries Government Documents Department