14 research outputs found
Conformality or confinement: (IR)relevance of topological excitations
We study aspects of the conformality to confinement transition for
non-supersymmetric Yang-Mills theories with fermions in arbitrary chiral or
vectorlike representations. We use the presence or absence of mass gap for
gauge fluctuations as an identifier of the infrared behavior. Present-day
understanding does not allow the mass gap for gauge fluctuations to be computed
on R*4. However, recent progress allows its non-perturbative computation on
R*3xS*1 by using either the twisted partition function or deformation theory,
for a range of S*1 sizes depending on the theory. For small number of fermions,
Nf, we show that the mass gap increases with increasing radius, due to the
non-dilution of monopoles and bions, the topological excitations relevant for
confinement on R*3xS*1. For sufficiently large Nf, we show that the mass gap
decreases with increasing radius. In a class of theories, we claim that the
decompactification limit can be taken while remaining within the region of
validity of semi-classical techniques, giving the first examples of
semiclassically solvable Yang-Mills theories at any size S*1. For general
non-supersymmetric vectorlike or chiral theories, we conjecture that the change
in the behavior of the mass gap on R*3xS*1 as a function of the radius occurs
near the lower boundary of the conformal window and give non-perturbative
estimates of its value. For vectorlike theories, we compare our estimates of
the conformal window with existing lattice results, truncations of the
Schwinger-Dyson equations, NSVZ beta function-inspired estimates, and degree of
freedom counting criteria. For multi-generation chiral gauge theories, to the
best of our knowledge, our estimates of the conformal window are the only known
ones.Comment: 40 pages, 3 figures; modified various comments, reference adde
CP Violation in a Supersymmetric SO(10) x U(2)_{F} Model
A model based on SUSY SO(10) combined with U(2) family symmetry constructed
recently by the authors is generalized to include phases in the mass matrices
leading to CP violation. In contrast with the commonly used effective operator
approach, -dimensional Higgs fields are utilized to construct the
Yukawa sector. R-parity symmetry is thus preserved at low energies. The
symmetric mass textures arising from the left-right symmetry breaking chain of
SO(10) give rise to very good predictions for quark and lepton masses and
mixings. The prediction for agrees with the average of current
bounds from BaBar and Belle. In the neutrino sector, our predictions are in
good agreement with results from atmospheric neutrino experiments. Our model
favors both the LOW and QVO solutions to the solar neutrino anomaly; the matrix
element for neutrinoless double beta decay is highly suppressed. The leptonic
analog of the Jarlskog invariant, , is predicted to be of
.Comment: RevTeX4; 7 pages; typos corrected; clarification remarks added; more
references added. To appear in Physical Review