320 research outputs found
First lattice evidence for a non-trivial renormalization of the Higgs condensate
General arguments related to ``triviality'' predict that, in the broken phase
of theory, the condensate re-scales by a factor
$Z_{\phi}$ different from the conventional wavefunction-renormalization factor,
$Z_{prop}$. Using a lattice simulation in the Ising limit we measure
$Z_{\phi}=m^2 \chi$ from the physical mass and susceptibility and $Z_{prop}$
from the residue of the shifted-field propagator. We find that the two $Z$'s
differ, with the difference increasing rapidly as the continuum limit is
approached. Since $Z_{\phi}$ affects the relation of to the Fermi
constant it can sizeably affect the present bounds on the Higgs mass.Comment: 10 pages, 3 figures, 1 table, Latex2
Physical mechanisms generating spontaneous symmetry breaking and a hierarchy of scales
We discuss the phase transition in 3+1 dimensional lambda Phi^4 theory from a
very physical perspective. The particles of the symmetric phase (`phions')
interact via a hard-core repulsion and an induced, long-range -1/r^3
attraction. If the phion mass is sufficiently small, the lowest-energy state is
not the `empty' state with no phions, but is a state with a non-zero density of
phions Bose-Einstein condensed in the zero-momentum mode. The condensate
corresponds to the spontaneous-symmetry-breaking vacuum with neq 0 and
its excitations ("phonons" in atomic-physics language) correspond to Higgs
particles. The phase transition happens when the phion's physical mass m is
still positive; it does not wait until m^2 passes through zero and becomes
negative. However, at and near the phase transition, m is much, much less than
the Higgs mass M_h. This interesting physics coexists with `triviality;' all
scattering amplitudes vanish in the continuum limit, but the vacuum condensate
becomes infinitely dense. The ratio m/M_h, which goes to zero in the continuum
limit, can be viewed as a measure of non-locality in the regularized theory. An
intricate hierarchy of length scales naturally arises. We speculate about the
possible implications of these ideas for gravity and inflation.Comment: 27 pages plus 2 files of figure
Zero mode in the time-dependent symmetry breaking of theory
We apply the quartic exponential variational approximation to the symmetry
breaking phenomena of scalar field in three and four dimensions. We calculate
effective potential and effective action for the time-dependent system by
separating the zero mode from other non-zero modes of the scalar field and
treating the zero mode quantum mechanically. It is shown that the quantum
mechanical properties of the zero mode play a non-trivial role in the symmetry
breaking of the scalar theory.Comment: 10 pages, 3 figure
Autonomous Renormalization of Phi^4 in Finite Geometry
The autonomous renormalization of the O(N)-symmetric scalar theory is based
on an infinite re-scaling of constant fields, whereas finite-momentum modes
remain finite. The natural framework for a detailed analysis of this method is
a system of finite size, where all non-constant modes can be integrated out
perturbatively and the constant mode is treated by a saddle-point approximation
in the thermodynamic limit. The calculation provides a better understanding of
the properties of of the effective action and corroborates earlier findings
concerning a heavy Higgs particle at about 2 TeV.Comment: 8 pages, Late
Fractal Spin Glass Properties of Low Energy Configurations in the Frenkel-Kontorova chain
We study numerically and analytically the classical one-dimensional
Frenkel-Kontorova chain in the regime of pinned phase characterized by phonon
gap. Our results show the existence of exponentially many static equilibrium
configurations which are exponentially close to the energy of the ground state.
The energies of these configurations form a fractal quasi-degenerate band
structure which is described on the basis of elementary excitations. Contrary
to the ground state, the configurations inside these bands are disordered.Comment: revtex, 9 pages, 9 figure
A One-Layer Satellite Surface Energy Balance for Estimating Evapotranspiration Rates and Crop Water Stress Indexes
Daily evapotranspiration fluxes over the semi-arid Catania Plain area (Eastern Sicily, Italy) were evaluated using remotely sensed data from Landsat Thematic Mapper TM5 images. A one-source parameterization of the surface sensible heat flux exchange using satellite surface temperature has been used. The transfer of sensible and latent heat is described by aerodynamic resistance and surface resistance. Required model inputs are brightness, temperature, fractional vegetation cover or leaf area index, albedo, crop height, roughness lengths, net radiation, air temperature, air humidity and wind speed. The aerodynamic resistance (rah) is formulated on the basis of the Monin-Obukhov surface layer similarity theory and the surface resistance (rs) is evaluated from the energy balance equation. The instantaneous surface flux values were converted into evaporative fraction (EF) over the heterogeneous land surface to derive daily evapotranspiration values. Remote sensing-based assessments of crop water stress (CWSI) were also made in order to identify local irrigation requirements. Evapotranspiration data and crop coefficient values obtained from the approach were compared with: (i) data from the semi-empirical approach “Kc reflectance-based”, which integrates satellite data in the visible and NIR regions of the electromagnetic spectrum with ground-based measurements and (ii) surface energy flux measurements collected from a micrometeorological tower located in the experiment area. The expected variability associated with ET flux measurements suggests that the approach-derived surface fluxes were in acceptable agreement with the observations
The prognostic value of the myeloid-mediated immunosuppression marker Arginase-1 in classic Hodgkin Lymphoma
Neutrophilia is hallmark of classic Hodgkin Lymphoma (cHL), but its precise characterization remains elusive. We aimed at investigating the immunosuppressive role of high-density neutrophils in HL
Incorporation of QCD Effects in Basic Corrections of the Electroweak Theory
We study the incorporation of QCD effects in the basic electroweak
corrections \drcar, \drcarw, and \dr. They include perturbative
\Ord{\alpha\alpha_s} contributions and threshold effects. The latter
are studied in the resonance and Green-function approaches, in the framework of
dispersion relations that automatically satisfy relevant Ward identities.
Refinements in the treatment of the electroweak corrections, in both the \ms\
and the on-shell schemes of renormalization, are introduced, including the
decoupling of the top quark in certain amplitudes, its effect on
\hat{e}^2(\mz) and \sincarmz, the incorporation of recent results on the
leading irreducible \Ord{\alpha^2} corrections, and simple expressions for the
residual, i.e.\ ``non-electromagnetic'', parts of \drcar, \drcarw, and \dr. The
results are used to obtain accurate values for \mw\ and \sincarmz, as functions
of \mt\ and \mh. The higher-order effects induce shifts in these parameters
comparable to the expected experimental accuracy, and they increase the
prediction for \mt\ derived from current measurements. The \ms\ and the
on-shell calculations of \dr, in a recently proposed formulation, are compared
and found to be in excellent agreement over the wide ranges 60\GeV \leq \mh
\leq 1 \TeV, \mz \leq \mt \leq 250 \GeV.Comment: 51 pages (needs doublespace, equations, and cite styles
Larval control of Anopheles (Nyssorhinchus) darlingiusing granular formulation of Bacillus sphaericus in abandoned gold-miners excavation pools in the Brazilian Amazon Rainforest
Perturbation Theory with a Variational Basis: the Generalized Gaussian Effective Potential
The perturbation theory with a variational basis is constructed and
analyzed.The generalized Gaussian effective potential is introduced and
evaluated up to the second order for selfinteracting scalar fields in one and
two spatial dimensions. The problem of the renormalization of the mass is
discussed in details. Thermal corrections are incorporated. The comparison
between the finite temperature generalized Gaussian effective potential and the
finite temperature effective potential is critically analyzed. The phenomenon
of the restoration at high temperature of the symmetry broken at zero
temperature is discussed.Comment: RevTex, 49 pages, 16 eps figure
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