1,752 research outputs found
Quantization of the scalar field in a static quantum metric
We investigate the Hamiltonian formulation of quantum scalar fields in a
static quantum metric. We derive a functional integral formula for the
propagator. We show that the quantum metric substantially changes the behaviour
of the scalar propagator and the effective Yukawa potential.Comment: Latex, 12 page
A general formula of the effective potential in 5D SU(N) gauge theory on orbifold
We show a general formula of the one loop effective potential of the 5D SU(N)
gauge theory compactified on an orbifold, . The formula shows the case
when there are fundamental, (anti-)symmetric tensor and adjoint
representational bulk fields. Our calculation method is also applicable when
there are bulk fields belonging to higher dimensional representations. The
supersymmetric version of the effective potential with Scherk-Schwarz breaking
can be obtained straightforwardly. We also show some examples of effective
potentials in SU(3), SU(5) and SU(6) models with various boundary conditions,
which are reproduced by our general formula.Comment: 22 pages;minor corrections;references added;typos correcte
Is really related to the solar neutrino solutions?
It has been said that the measurements of in the lepton flavor
mixing matrix would help discriminate between the possible solar neutrino
solutions under the natural conditions with the neutrino mass hierarchies of
and , where is the -th
generation neutrino absolute mass. However, it is not true, and the relation
between and obtained by Akhmedov, Branco, and
Rebelo is trivial in actual. We show in this paper that the value of
cannot predict the solar neutrino solutions without one additional nontrivial
condition.Comment: 7pages, no figur
Anarchy and Hierarchy
We advocate a new approach to study models of fermion masses and mixings,
namely anarchy proposed in hep-ph/9911341. In this approach, we scan the O(1)
coefficients randomly. We argue that this is the correct approach when the
fundamental theory is sufficiently complicated. Assuming there is no physical
distinction among three generations of neutrinos, the probability distributions
in MNS mixing angles can be predicted independent of the choice of the measure.
This is because the mixing angles are distributed according to the Haar measure
of the Lie groups whose elements diagonalize the mass matrices. The
near-maximal mixings, as observed in the atmospheric neutrino data and as
required in the LMA solution to the solar neutrino problem, are highly
probable. A small hierarchy between the Delta m^2 for the atmospheric and the
solar neutrinos is obtained very easily; the complex seesaw case gives a
hierarchy of a factor of 20 as the most probable one, even though this
conclusion is more measure-dependent. U_{e3} has to be just below the current
limit from the CHOOZ experiment. The CP-violating parameter sin delta is
preferred to be maximal. We present a simple SU(5)-like extension of anarchy to
the charged-lepton and quark sectors which works well phenomenologically.Comment: 26 page
Decoherence in QED at finite temperature
We consider a wave packet of a charged particle passing through a cavity
filled with photons at temperature T and investigate its localization and
interference properties. It is shown that the wave packet becomes localized and
the interference disappears with an exponential speed after a sufficiently long
path through the cavity.Comment: Latex, 10 page
Green functions and propagation of waves in strongly inhomogeneous media
We show that Green functions of second-order differential operators with
singular or unbounded coefficients can have an anomalous behaviour in
comparison to the well-known properties of Green functions of operators with
bounded coefficients. We discuss some consequences of such an anomalous short
or long distance behaviour for a diffusion and wave propagation in an
inhomogeneous medium
Temperature Inversion Symmetry in Gauge-Higgs Unification Models
The temperature inversion symmetry is studied for the
finite temperature effective potential of the N=1, , supersymmetric
model, on the orbifold . For the
value of the Wilson line parameter ( breaks to a
), it is found that the effective potential contains a symmetric part
and an anti-symmetric part under , with, . When
(for which, remains unbroken) it is found that the only
contribution to the effective potential that spoils the temperature inversion
symmetry comes from the fermions in the fundamental representation of the gauge
group, with or , parities. This is interesting since it
implies that the bulk effective potential corresponding to models with orbifold
fixed point localized fundamental fermions (and with no bulk fundamental
fermions) has the temperature inversion symmetry.Comment: 21 pages, version accepted for publication in Theoretical and
Mathematical Physic
Relativistic diffusive motion in random electromagnetic fields
We show that the relativistic dynamics in a Gaussian random electromagnetic
field can be approximated by the relativistic diffusion of Schay and Dudley.
Lorentz invariant dynamics in the proper time leads to the diffusion in the
proper time. The dynamics in the laboratory time gives the diffusive transport
equation corresponding to the Juettner equilibrium at the inverse temperature
\beta^{-1}=mc^{2}. The diffusion constant is expressed by the field strength
correlation function (Kubo's formula).Comment: the version published in JP
Quarks and Leptons between Branes and Bulk
We study a supersymmetric SO(10) gauge theory in six dimensions compactified
on an orbifold. Three sequential quark-lepton families are localized at the
three fixpoints where SO(10) is broken to its three GUT subgroups. Split bulk
multiplets yield the Higgs doublets of the standard model and as additional
states lepton doublets and down-quark singlets. The physical quarks and leptons
are mixtures of brane and bulk states. The model naturally explains small quark
mixings together with large lepton mixings in the charged current. A small
hierarchy of neutrino masses is obtained due to the different down-quark and
up-quark mass hierarchies. None of the usual GUT relations between fermion
masses holds exactly.Comment: 12 pages, 1 figur
Gauge-Higgs Dark Matter
When the anti-periodic boundary condition is imposed for a bulk field in
extradimensional theories, independently of the background metric, the lightest
component in the anti-periodic field becomes stable and hence a good candidate
for the dark matter in the effective 4D theory due to the remaining accidental
discrete symmetry. Noting that in the gauge-Higgs unification scenario,
introduction of anti-periodic fermions is well-motivated by a phenomenological
reason, we investigate dark matter physics in the scenario. As an example, we
consider a five-dimensional SO(5)\timesU(1)_X gauge-Higgs unification model
compactified on the with the warped metric. Due to the structure of
the gauge-Higgs unification, interactions between the dark matter particle and
the Standard Model particles are largely controlled by the gauge symmetry, and
hence the model has a strong predictive power for the dark matter physics.
Evaluating the dark matter relic abundance, we identify a parameter region
consistent with the current observations. Furthermore, we calculate the elastic
scattering cross section between the dark matter particle and nucleon and find
that a part of the parameter region is already excluded by the current
experimental results for the direct dark matter search and most of the region
will be explored in future experiments.Comment: 16 pages, 2 figure
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