317 research outputs found
Phenomenological studies in the matrix models
Matrix models are a promising candidate for a nonperturbative formulation of
the superstring theory. It is possible to study how the standard model and
other phenomenological models appear from the matrix model, and estimate the
probability distribution of their appearance. This article mainly addresses
studies in toroidal compactifications with magnetic fluxes.Comment: 5 pages; contribution to the proceedings of the Workshop on
Noncommutative Field Theory and Gravity, Corfu, Greece, September 8-15, 2013;
to appear in Fortsch. Phy
Chiral Fermions and the Standard Model from the Matrix Model Compactified on a Torus
It is shown that the IIB matrix model compactified on a six-dimensional torus
with a nontrivial topology can provide chiral fermions and matter content close
to the standard model on our four-dimensional spacetime. In particular,
generation number three is given by the Dirac index on the torus.Comment: 21 pages, 5 figures; ver2: version published in Prog. Theor. Phys;
ver3: minor correction
Index Theorem in Finite Noncommutative Geometry
Index theorem is formulated in noncommutative geometry with finite degrees of
freedom by using Ginsparg-Wilson relation. It is extended to the case where the
gauge symmetry is spontaneously broken. Dynamical analysis about topological
aspects in gauge theory is also shown.Comment: Latex 4 pages, uses ptptex.cls, Based on talk given at 21st
Nishinomiya-Yukawa Memorial Symposium on Theoretical Physics: Noncommutative
Geometry and Quantum Spacetime in Physics, Japan, 11-15 Nov 200
Realizing three generations of the Standard Model fermions in the type IIB matrix model
We discuss how the Standard Model particles appear from the type IIB matrix
model, which is considered to be a nonperturbative formulation of superstring
theory. In particular, we are concerned with a constructive definition of the
theory, in which we start with finite-N matrices and take the large-N limit
afterwards. In that case, it was pointed out recently that realizing chiral
fermions in the model is more difficult than it had been thought from formal
arguments at N=infinity and that introduction of a matrix version of the warp
factor is necessary. Based on this new insight, we show that two generations of
the Standard Model fermions can be realized by considering a rather generic
configuration of fuzzy S^2 and fuzzy S^2 * S^2 in the extra dimensions. We also
show that three generations can be obtained by squashing one of the S^2's that
appear in the configuration. Chiral fermions appear at the intersections of the
fuzzy manifolds with nontrivial Yukawa couplings to the Higgs field, which can
be calculated from the overlap of their wave functions.Comment: 28 pages, 11 figures; (v2) references added, typos corrected; (v3)
footnote added, version to be published on JHE
Hofstadter butterflies for flat bands
Hofstadter's diagram, or the energy spectrum against the magnetic field in
tight-binding systems, is obtained for the models having flat (dispersionless)
one-electron band(s) that have originally been proposed for itinerant spin
ferromagnetism. Magnetic fields preserve those flat bands that arise from a
topological reason, while dispersions emerge in a singular manner for the flat
bands arising from interference, implying an anomalous orbital magnetism.Comment: 9 pages, revtex, 4 figures available on request from
[email protected]
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