216 research outputs found
Chaotic scalar fields as models for dark energy
We consider stochastically quantized self-interacting scalar fields as
suitable models to generate dark energy in the universe. Second quantization
effects lead to new and unexpected phenomena is the self interaction strength
is strong. The stochastically quantized dynamics can degenerate to a chaotic
dynamics conjugated to a Bernoulli shift in fictitious time, and the right
amount of vacuum energy density can be generated without fine tuning. It is
numerically observed that the scalar field dynamics distinguishes fundamental
parameters such as the electroweak and strong coupling constants as
corresponding to local minima in the dark energy landscape. Chaotic fields can
offer possible solutions to the cosmological coincidence problem, as well as to
the problem of uniqueness of vacua.Comment: 30 pages, 3 figures. Replaced by final version accepted by Phys. Rev.
New Classes of Off-Diagonal Cosmological Solutions in Einstein Gravity
In this work, we apply the anholonomic deformation method for constructing
new classes of anisotropic cosmological solutions in Einstein gravity and/or
generalizations with nonholonomic variables. There are analyzed four types of,
in general, inhomogeneous metrics, defined with respect to anholonomic frames
and their main geometric properties. Such spacetimes contain as particular
cases certain conformal and/or frame transforms of the well known
Friedman-Robertson-Walker, Bianchi, Kasner and Godel universes and define a
great variety of cosmological models with generic off-diagonal metrics, local
anisotropy and inhomogeneity. It is shown that certain nonholonomic
gravitational configurations may mimic de Sitter like inflation scenaria and
different anisotropic modifications without satisfying any classical
false-vacuum equation of state. Finally, we speculate on perspectives when such
off-diagonal solutions can be related to dark energy and dark matter problems
in modern cosmology.Comment: latex2e, 11pt, 33 pages with table of content, a variant accepted to
IJT
Large and Unified Description of Quark and Lepton Mixing Matrices
We present a revised version of the so-called "yukawaon model", which was
proposed for the purpose of a unified description of the lepton mixing matrix
and the quark mixing matrix . It is assumed from a
phenomenological point of view that the neutrino Dirac mass matrix is
given with a somewhat different structure from the charged lepton mass matrix
, although was assumed in the previous model. As a result, the
revised model predicts a reasonable value with
keeping successful results for other parameters in as well as
and quark and lepton mass ratios.Comment: 13 pages, 3 figures, version accepted by EPJ
The hyperon-nucleon interaction: conventional versus effective field theory approach
Hyperon-nucleon interactions are presented that are derived either in the
conventional meson-exchange picture or within leading order chiral effective
field theory. The chiral potential consists of one-pseudoscalar-meson exchanges
and non-derivative four-baryon contact terms. With regard to meson-exchange
hyperon-nucleon models we focus on the new potential of the Juelich group,
whose most salient feature is that the contributions in the scalar--isoscalar
(\sigma) and vector--isovector (\rho) exchange channels are constrained by a
microscopic model of correlated \pi\pi and KKbar exchange.Comment: 28 pages, 8 figures, submitted to Lecture Notes in Physic
Trialogue on the number of fundamental constants
This paper consists of three separate articles on the number of fundamental
dimensionful constants in physics. We started our debate in summer 1992 on the
terrace of the famous CERN cafeteria. In the summer of 2001 we returned to the
subject to find that our views still diverged and decided to explain our
current positions. LBO develops the traditional approach with three constants,
GV argues in favor of at most two (within superstring theory), while MJD
advocates zero.Comment: Version appearing in JHEP; 31 pages late
Thermodynamics of an Anyon System
We examine the thermal behavior of a relativistic anyon system, dynamically
realized by coupling a charged massive spin-1 field to a Chern-Simons gauge
field. We calculate the free energy (to the next leading order), from which all
thermodynamic quantities can be determined. As examples, the dependence of
particle density on the anyon statistics and the anyon anti-anyon interference
in the ideal gas are exhibited. We also calculate two and three-point
correlation functions, and uncover certain physical features of the system in
thermal equilibrium.Comment: 18 pages; in latex; to be published in Phys. Rev.
DLCQ of Fivebranes, Large N Screening, and L^2 Harmonic Forms on Calabi Manifolds
We find one explicit L^2 harmonic form for every Calabi manifold. Calabi
manifolds are known to arise in low energy dynamics of solitons in Yang-Mills
theories, and the L^2 harmonic form corresponds to the supersymmetric ground
state. As the normalizable ground state of a single U(N) instanton, it is
related to the bound state of a single D0 to multiple coincident D4's in the
non-commutative setting, or equivalently a unit Kaluza-Klein mode in DLCQ of
fivebrane worldvolume theory. As the ground state of nonabelian massless
monopoles realized around a monopole-``anti''-monopole pair, it shows how the
long range force between the pair is screened in a manner reminiscent of large
N behavior of quark-anti-quark potential found in AdS/CFT correspondence.Comment: LaTeX, 23 page
Analytic structure of rho meson propagator at finite temperature
We analyse the structure of one-loop self-energy graphs for the rho meson in
real time formulation of finite temperature field theory. We find the
discontinuities of these graphs across the unitary and the Landau cuts. These
contributions are identified with different sources of medium modification
discussed in the literature. We also calculate numerically the imaginary and
the real parts of the self-energies and construct the spectral function of the
rho meson, which are compared with an earlier determination. A significant
contribution arises from the unitary cut of the pi-omega loop, that was ignored
so far in the literature
Facial recognition from DNA using face-to-DNA classifiers
Facial recognition from DNA refers to the identification or verification of unidentified biological material against facial images with known identity. One approach to establish the identity of unidentified biological material is to predict the face from DNA, and subsequently to match against facial images. However, DNA phenotyping of the human face remains challenging. Here, another proof of concept to biometric authentication is established by using multiple face-to-DNA classifiers, each classifying given faces by a DNA-encoded aspect (sex, genomic background, individual genetic l
Magnetic Charge Lattices, Moduli Spaces and Fusion Rules
We analyze the set of magnetic charges carried by smooth BPS monopoles in
Yang-Mills-Higgs theory with arbitrary gauge group G spontaneously broken to a
subgroup H. The charges are restricted by a generalized Dirac quantization
condition and by an inequality due to Murray. Geometrically, the set of allowed
charges is a solid cone in the coroot lattice of G, which we call the Murray
cone. We argue that magnetic charge sectors correspond to points in the Murray
cone divided by the Weyl group of H; hence magnetic charge sectors are labelled
by dominant integral weights of the dual group H*. We define generators of the
Murray cone modulo Weyl group, and interpret the monopoles in the associated
magnetic charge sectors as basic; monopoles in sectors with decomposable
charges are interpreted as composite configurations. This interpretation is
supported by the dimensionality of the moduli spaces associated to the magnetic
charges and by classical fusion properties for smooth monopoles in particular
cases. Throughout the paper we compare our findings with corresponding results
for singular monopoles recently obtained by Kapustin and Witten.Comment: 53 pages, 6 figure
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