2,601 research outputs found
The evolution of vacuum states and phase transitions in 2HDM during cooling of Universe
We consider the evolution of the ground state in the Two Higgs Doublet Model
during cooling down of the Universe after the Big Bang. Different regions in
the space of free parameters of this model correspond to different sequences of
thermal phase transitions. We discuss different paths of thermal evolution and
corresponding evolution of physical properties of the system for different
modern values of the parameters.Comment: 28 pages, 12 figure
Evolution of Universe to the present inert phase
We assume that current state of the Universe can be described by the Inert
Doublet Model, containing two scalar doublets, one of which is responsible for
EWSB and masses of particles and the second one having no couplings to fermions
and being responsible for dark matter. We consider possible evolutions of the
Universe to this state during cooling down of the Universe after inflation. We
found that in the past Universe could pass through phase states having no DM
candidate. In the evolution via such states in addition to a possible EWSB
phase transition (2-nd order) the Universe sustained one 1-st order phase
transition or two phase transitions of the 2-nd order.Comment: 19 pages, 3 figure
Proximity effect in clean strong/weak/strong superconducting tri-layers
Recent measurements of the Josephson critical current through LSCO/LCO/LSCO
thin films showed an unusually large proximity effect. Using the Bogoliubov-de
Gennes (BdG) equations for a tight binding Hamiltonian we describe the
proximity effect in weak links between a superconductor with critical
temperature and one with critical temperature ', where '.
The weak link (N') is therefore a superconductor above its own critical
temperature and the superconducting regions are considered to have either
s-wave or d-wave symmetry. We note that the proximity effect is enhanced due to
the presence of superconducting correlations in the weak link. The dc Josephson
current is calculated, and we obtain a non-zero value for temperatures greater
than ' for sizes of the weak links that can be almost an order of
magnitude greater than the conventional coherence length. Considering pockets
of superconductivity in the N' layer, we show that this can lead to an even
larger effect on the Josephson critical current by effectively shortening the
weak link.Comment: submitted to Physical Review
Gravitational Laser Back-Scattering
A possible way of producing gravitons in the laboratory is investigated. We
evaluate the cross section electron + photon electron + graviton
in the framework of linearized gravitation, and analyse this reaction
considering the photon coming either from a laser beam or from a Compton
back-scattering process.Comment: 11 pages, 2 figures (available upon request), RevTeX, IFT-P.03/9
Spatial and Temporal Noise Spectra of Spatially Extended Systems with Order-Disorder Phase Transitions
The noise power spectra of spatially extended dynamical systems are
investigated, using as a model the Complex Ginzburg-Landau equation with a
stochastic term. Analytical and numerical investigations show that the spatial
spectra of the ordered state are similar to Bose-Einstein distribution, showing
1/k^2 asymptotics in the long wavelength limit. The temporal noise spectra of
the ordered state are obtained of 1/^alpha form, where alpha=2-D/2 with D the
spatial dimension of the system.Comment: to be printed in International Journal of Bifurcation and Chao
Diffractive photoproduction of opposite-charge pseudoscalar meson pairs at high energies
We calculate the cross section for diffractive photoproduction of
opposite-charge pseudoscalar meson pairs , ,
and in a broad range of center-of-mass energies relevant
for GlueX/Hall D, FOCUS, COMPASS and HERA experiments. In the case of
production we find that the interference of the resonance
and the two-pion continuum leads to a considerable deformation of the shape of
in agreement with the data from the ZEUS collaboration. We also
discuss the spectral shape of the as a function of the momentum
transfer and the contribution of higher partial waves to the mass
spectrum. We predict a sizeable energy-dependent forward-backward asymmetry in
the Gottfried-Jackson frame. For the heavy meson production we find that the
cross section for diffractive production increases much slower than the one for
open charm or bottom production. We discuss lower and upper limits for the
cross sections for diffractive production of and pairs,
which we find can be as large as 10% of the open flavor production.Comment: 14 pages, 19 figure
Identifying the Higgs Boson in Electron--Photon Collisions
We analyze the production and detection of the Higgs boson in the next
generation of linear colliders operating in the mode. In
particular, we study the production mechanism , where one photon is generated via the laser
backscattering mechanism, while the other is radiated via the usual
bremsstrahlung process. We show that this is the most important mechanism for
Higgs boson production in a GeV collider for
M_H\raisebox{-.4ex}{\rlap{\sim}} \raisebox{.4ex}{>}140 GeV. We also study
the signals and backgrounds for detection of the Higgs in the different decay
channels, , , and , and suggest kinematical cuts to
improve the signature of an intermediate mass Higgs boson.Comment: (REVTEX 2.0, 12 pages and 9 figures available upon request, Preprint
MAD/PH/753
Motion of vortices in type II superconductors
The methods of formal asymptotics are used to examine the behaviour of a system of curvilinear vortices in a type II superconductor as the thickness of the vortex cores tends to zero. The vortices then appear as singularities in the field equation and are analagous to line vortices in inviscid hydrodynamics. A local analysis near each vortex core gives an equation of motion governing the evolution of these singularities
The phase evolution of the Universe during its cooling down in 2HDM
Two Higgs Doublet Model at different values of parameters realizes ground state (vacuum) with different properties. The parameters of the Gibbs potential are varied during cooling down of the Universe after Big Bang. At this
variation properties of vacuum state can vary, Universe suffers phase transitions. The evolution of phase states and chains of phase transitions can be much more diverse
than in Standard Model with single Higgs doublet. We analyzed phase history of earlier Universe for each set of parameters and find sets of modern parameters, responsible for different chains of thermal phase transitions
and couplings in collision with polarized beams
The potential of e mode of linear collider to probe
and vertices is investigated through the Z boson
production from the procees . Considering the longitudinal and
transverse polarization states of the Z boson and incoming polarized beams we
find the 95% C.L. limits on the form factors , ,
and with integrated luminosity 500
and 0.5, 1, 1.5 TeV energies. It is shown that the polarization can
improve sensitivities by factors 2-3 depending on the energy.Comment: 12 pages, 8 EPS figure
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