183,305 research outputs found
Non-Abelian Gauge Field Localized on Walls with Four-Dimensional World Volume
A mechanism using the position-dependent gauge coupling is proposed to
localize non-Abelian gauge fields on domain walls in five-dimensional
space-time. Low-energy effective theory posseses a massless vector field, and a
mass gap. The four-dimensional gauge invariance is maintained intact. We obtain
perturbatively the four-dimensional Coulomb law for static sources on the
domain wall. BPS domain wall solutions with the localization mechanism are
explicitly constructed in the U(1)xU(1) supersymmetric gauge theory coupling to
the non-Abelian gauge fields only through the cubic prepotential, which is
consistent with the general principle of supersymmetry in five-dimensional
space-time.Comment: 22 pages, 5 figures, 5 references added for section
Rational Maps, Monopoles and Skyrmions
We discuss the similarities between BPS monopoles and Skyrmions, and point to
an underlying connection in terms of rational maps between Riemann spheres.
This involves the introduction of a new ansatz for Skyrme fields. We use this
to construct good approximations to several known Skyrmions, including all the
minimal energy configurations up to baryon number nine, and some new solutions
such as a baryon number seventeen Skyrme field with the truncated icosahedron
structure of a buckyball.
The new approach is also used to understand the low-lying vibrational modes
of Skyrmions, which are required for quantization. Along the way we discover an
interesting Morse function on the space of rational maps which may be of use in
understanding the Sen forms on the monopole moduli spaces.Comment: 35pp including four figures, typos corrected, appearing in Nuclear
Physics
Chiral Symmetry Breaking and Meson Wave Functions in Soft-Wall AdS/QCD
We consider mesons composed of light and heavy quarks and discuss the
construction of the corresponding meson wave functions in soft-wall AdS/QCD. We
specifically take care that constraints imposed by chiral symmetry breaking and
by the heavy quark limit are fulfilled. The main results are: i) the wave
functions of light mesons have a nontrivial dependence on the current quark
mass, which gives rise to a mass spectrum consistent with the one including
explicit breaking of chiral symmetry; ii) the wave functions of heavy-light
mesons generate their correct mass spectrum, the mass splittings of vector and
pseudoscalar states, and the correct scaling of leptonic decay constants f(Q
\bar q) \sim 1/sqrt(mQ); iii) the wave functions of heavy quarkonia produce
their correct mass spectrum and lead to a scaling behaviour of the leptonic
decay constants f(Q \bar Q) \sim sqrt(mQ) and f(c \bar b) \sim mc/sqrt(mb) at
mc << mb, consistent with potential models and QCD sum rules.Comment: 10 page
Two-point Functions and Quantum Fields in de Sitter Universe
We present a theory of general two-point functions and of generalized free
fields in d-dimensional de Sitter space-time which closely parallels the
corresponding minkowskian theory. The usual spectral condition is now replaced
by a certain geodesic spectral condition, equivalent to a precise thermal
characterization of the corresponding ``vacuum''states. Our method is based on
the geometry of the complex de Sitter space-time and on the introduction of a
class of holomorphic functions on this manifold, called perikernels, which
reproduce mutatis mutandis the structural properties of the two-point
correlation functions of the minkowskian quantum field theory. The theory
contains as basic elementary case the linear massive field models in their
``preferred'' representation. The latter are described by the introduction of
de Sitter plane waves in their tube domains which lead to a new integral
representation of the two-point functions and to a Fourier-Laplace type
transformation on the hyperboloid. The Hilbert space structure of these
theories is then analysed by using this transformation. In particular we show
the Reeh-Schlieder property. For general two-point functions, a substitute to
the Wick rotation is defined both in complex space-time and in the complex mass
variable, and substantial results concerning the derivation of Kallen-Lehmann
type representation are obtained.Comment: 51 p, uuencoded, LaTex, epsf, 2 figures include
Flavor Structure in F-theory Compactifications
F-theory is one of frameworks in string theory where supersymmetric grand
unification is accommodated, and all the Yukawa couplings and Majorana masses
of right-handed neutrinos are generated. Yukawa couplings of charged fermions
are generated at codimension-3 singularities, and a contribution from a given
singularity point is known to be approximately rank 1. Thus, the approximate
rank of Yukawa matrices in low-energy effective theory of generic F-theory
compactifications are minimum of either the number of generations N_gen = 3 or
the number of singularity points of certain types. If there is a geometry with
only one E_6 type point and one D_6 type point over the entire 7-brane for
SU(5) gauge fields, F-theory compactified on such a geometry would reproduce
approximately rank-1 Yukawa matrices in the real world. We found, however, that
there is no such geometry. Thus, it is a problem how to generate hierarchical
Yukawa eigenvalues in F-theory compactifications. A solution in the literature
so far is to take an appropriate factorization limit. In this article, we
propose an alternative solution to the hierarchical structure problem (which
requires to tune some parameters) by studying how zero mode wavefunctions
depend on complex structure moduli. In this solution, the N_gen x N_gen CKM
matrix is predicted to have only N_gen entries of order unity without an extra
tuning of parameters, and the lepton flavor anarchy is predicted for the lepton
mixing matrix. We also obtained a precise description of zero mode
wavefunctions near the E_6 type singularity points, where the up-type Yukawa
couplings are generated.Comment: 148 page
Non-Abelian vortices and monopoles in SO(N) theories
Non-Abelian BPS vortex solutions are constructed in N=2 theories with gauge
groups SO(N)\times U(1). The model has N_f flavors of chiral multiplets in the
vector representation of SO(N), and we consider a color-flavor locked vacuum in
which the gauge symmetry is completely broken, leaving a global SO(N)_{C+F}
diagonal symmetry unbroken. Individual vortices break this symmetry, acquiring
continuous non-Abelian orientational moduli. By embedding this model in
high-energy theories with a hierarchical symmetry breaking pattern such as
SO(N+2) --> SO(N)\times U(1) --> 1, the correspondence between non-Abelian
monopoles and vortices can be established through homotopy maps and flux
matching, generalizing the known results in SU(N) theories. We find some
interesting hints about the dual (non-Abelian) transformation properties among
the monopoles.Comment: LaTeX, 26 pages and 4 figure
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