1,219 research outputs found
Fractal Theory Space: Spacetime of Noninteger Dimensionality
We construct matter field theories in ``theory space'' that are fractal, and
invariant under geometrical renormalization group (RG) transformations. We
treat in detail complex scalars, and discuss issues related to fermions,
chirality, and Yang-Mills gauge fields. In the continuum limit these models
describe physics in a noninteger spatial dimension which appears above a RG
invariant ``compactification scale,'' M. The energy distribution of KK modes
above M is controlled by an exponent in a scaling relation of the vacuum energy
(Coleman-Weinberg potential), and corresponds to the dimensionality. For
truncated-s-simplex lattices with coordination number s the spacetime
dimensionality is 1+(3+2ln(s)/ln(s+2)). The computations in theory space
involve subtleties, owing to the 1+3 kinetic terms, yet the resulting
dimensionalites are equivalent to thermal spin systems. Physical implications
are discussed.Comment: 28 pages, 6 figures; Paper has been amplified with a more detailed
discussion of a number of technical issue
Natural Theories of Ultra-Low Mass PNGB's: Axions and Quintessence
We consider the Wilson Line PNGB which arises in a U(1)^N gauge theory,
abstracted from a latticized, periodically compactified extra dimension U(1).
Planck scale breaking of the PNGB's global symmetry is suppressed, providing
natural candidates for the axion and quintessence. We construct an explicit
model in which the axion may be viewed as the 5th component of the U(1)_Y gauge
field in a 1+4 latticized periodically compactified extra dimension. We also
construct a quintessence PNGB model where the ultra-low mass arises from
Planck-scale suppressed physics itself.Comment: 20 pages, fixed typo and reference
Coulomb Drag Between Parallel Ballistic Quantum Wires
The Coulomb drag between parallel, {\it ballistic} quantum wires is studied
theoretically in the presence of a perpendicular magnetic field B. The
transresistance R_D shows peaks as a function of the Fermi level and splitting
energy between the 1D subbands of the wires. The sharpest peaks appear when the
Fermi level crosses the subband extrema so that the Fermi momenta are small.
Two other kinds of peaks appear when either {\it intra}- or {\it inter}-subband
transitions of electrons have maximum probability; the {\it intra}-subband
transitions correspond to a small splitting energy. R_D depends on the field B
in a nonmonotonic fashion: it decreases with B, as a result of the suppression
of backscattering, and increases sharply when the Fermi level approaches the
subband bottoms and the suppression is outbalanced by the increase of the
Coulomb matrix elements and of the density of states.Comment: Text 14 pages in Latex/Revtex format, 4 Postscript figures. Phys.
Rev. B,in pres
Yukawa Deflected Gauge Mediation in Four Dimensions
We construct a four dimensional realization of a higher dimensional model,
Yukawa deflected gauge mediation, in which supersymmetry breaking is
communicated to the visible sector through both gauge and Yukawa interactions.
The reduction to four dimensions is achieved by `deconstructing' or
`latticizing' the extra dimension. Three sites (gauge groups) are sufficient to
reproduce the spectrum of the higher dimensional model. The characteristic
features of Yukawa deflected gauge mediation, in particular, alignment of
squarks and quarks, and a natural solution to the mu problem, carry over to the
deconstructed version of the model. We comment on the implications of our
results for a solution of the mu problem in the context of deconstructed
gaugino mediation.Comment: 11 pages, 1figur
Field localization in warped gauge theories
We present four-dimensional gauge theories that describe physics on
five-dimensional curved (warped) backgrounds, which includes bulk fields with
various spins (vectors, spinors, and scalars). Field theory on the AdS
geometry is examined as a simple example of our formulation. Various properties
of bulk fields on this background, e.g., the mass spectrum and field
localization behavior, can be achieved within a fully four-dimensional
framework. Moreover, that gives a localization mechanism for massless vector
fields. We also consider supersymmetric cases, and show in particular that the
conditions on bulk masses imposed by supersymmetry on warped backgrounds are
derived from a four-dimensional supersymmetric theory on the flat background.
As a phenomenological application, models are shown to generate hierarchical
Yukawa couplings. Finally, we discuss possible underlying mechanisms which
dynamically realize the required couplings to generate curved geometries.Comment: 24 pages, 12 figures; more explanation of nonuniversal gauge
couplings added, typos corrected, references update
Frictional drag between non-equilibrium charged gases
The frictional drag force between separated but coupled two-dimensional
electron gases of different temperatures is studied using the non-equilibrium
Green function method based on the separation of center-of-mass and relative
dynamics of electrons. As the mechanisms of producing the frictional force we
include the direct Coulomb interaction, the interaction mediated via virtual
and real TA and LA phonons, optic phonons, plasmons, and TA and LA
phonon-electron collective modes. We found that, when the distance between the
two electron gases is large, and at intermediate temperature where plasmons and
collective modes play the most important role in the frictional drag, the
possibility of having a temperature difference between two subsystems modifies
greatly the transresistivity.Comment: 8figure
Recommended from our members
Criteria for the recognition of pedogenic/supergene and nonpedogenic/hypogene deposits and their relationship to the origin of calcite/opal deposits at Yucca Mountain. Special report No. 14
This study is part of the research program of the Yucca Mountain Project intended to provide the State of Nevada with a detailed assessment of the geology and geochemistry of Yucca Mountain and adjacent regions. The purpose of this report is to try and establish criteria for the recognition of pedogenic/supergene deposits of calcite/opal versus non-pedogenic/hypogene deposits of calcite/opal. Far from being of esoteric concern, this subject is of paramount importance to the pedogenic-hypogene debate which rages around the suitability of Yucca Mountain as a high-level radioactive waste repository site
Topped MAC with extra dimensions?
We perform the most attractive channel (MAC) analysis in the top mode
standard model with TeV-scale extra dimensions, where the standard model gauge
bosons and the third generation of quarks and leptons are put in D(=6,8,10,...)
dimensions. In such a model, bulk gauge couplings rapidly grow in the
ultraviolet region. In order to make the scenario viable, only the attractive
force of the top condensate should exceed the critical coupling, while other
channels such as the bottom and tau condensates should not. We then find that
the top condensate can be the MAC for D=8, whereas the tau condensation is
favored for D=6. The analysis for D=10 strongly depends on the regularization
scheme. We predict masses of the top (m_t) and the Higgs (m_H), m_t=172-175 GeV
and m_H=176-188 GeV for D=8, based on the renormalization group for the top
Yukawa and Higgs quartic couplings with the compositeness conditions at the
scale where the bulk top condenses. The Higgs boson in such a characteristic
mass range will be immediately discovered in H -> WW^(*)/ZZ^(*) once the LHC
starts.Comment: REVTEX4, 24 pages, 21 figures, to appear in PRD. The title is changed
in PRD. One reference added, typos correcte
Localized Fermions and Anomaly Inflow via Deconstruction
We study fermion localization in gauge theory space. We consider four
dimensional product gauge groups in which light chiral fermions transform under
different gauge factors of the product group. This construction provides a
suppression of higher dimensional operators. For example, it can be used to
suppress dangerous proton decay operators. The anomalies associated with the
light chiral fermions are compensated by Wess-Zumino terms, which in the
continuum limit reproduce the five dimensional Chern-Simons term.Comment: 12 pages, minor changes to section
Lepton flavor violation decays in the topcolor-assisted technicolor model and the littlest Higgs model with parity
The new particles predicted by the topcolor-assisted technicolor ()
model and the littlest Higgs model with T-parity (called model) can
induce the lepton flavor violation () couplings at tree level or one loop
level, which might generate large contributions to some processes. Taking
into account the constraints of the experimental data on the relevant free
parameters, we calculate the branching ratios of the decay processes
with = , and
in the context of these two kinds of new physics models. We find
that the model and the model can indeed produce significant
contributions to some of these decay processes.Comment: 24 pages, 7 figure
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