18,166 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
On the two-loop divergences of the 2-point hypermultiplet supergraphs for , SYM theory
We consider , supersymmetric Yang-Mills theory
formulated in harmonic superspace and analyze the structure of
the two-loop divergences in the hypermultiplet sector. Using the superfield background field method we study the two-point supergraphs
with the hypermultiplet legs and prove that their total contribution to the
divergent part of effective action vanishes off shell.Comment: 8 pages, 2 figure
Supergraph analysis of the one-loop divergences in , and gauge theories
We study the one-loop effective action for
supersymmetric Yang--Mills (SYM) theory with hypermultiplets and SYM theory as a subclass of the former, using the off-shell
formulation of these theories in harmonic superspace. We
develop the corresponding supergraph technique and apply it to compute the
one-loop divergences in the background field method ensuring the manifest gauge
invariance. We calculate the two-point Green functions of the gauge superfield
and the hypermultiplet, as well as the three-point gauge-hypermultipet Green
function. Using these Green functions and exploiting gauge invariance of the
theory, we find the full set of the off-shell one-loop divergent contributions,
including the logarithmic and power ones. Our results precisely match with
those obtained earlier in [1,2] within the proper time superfield method.Comment: 32 pages, 5 figure
Different regimes of Purcell Effect in Disordered Photonic Crystals
We demonstrate that disorder in photonic crystals could lead to pronounced
modification of spontaneous emission rate in the frequency region corresponding
to the photonic band gap (PBG). Depending on the amount of disorder, two
different regimes of the Purcell effect occurs. For the moderate disorder, an
enhancement of spontaneous emission occurs at the edge of PBG due to
modification of the properties of the edge state. This effect is responsible
for recently observed mirrorless lasing in photonic crystals at the edge of
PBG. When the level of disorder increases, the spontaneous emission rate
enhances within the PBG due to the appearance of the high quality factor
states. This effect is likely responsible for a superlinear dependence of
emissions on the pumping observed in synthetic opals.Comment: 15 pages, 6 figures, appendi
Experimental methodology of study of damage initiation and development in textile composites in uniaxial tensile test
Damage in textile composites is closely connected with the internal micro- and meso-geometry of the reinforcement, and reveals features, which are not present in the damage processes in classical laminates. This paper proposes a test sequence intended to characterize damage in textile composites – its initiation and development different scale levels: (1) Tensile tests on samples cut in characteristic directions of the textile reinforcement (machine, cross and bias), accompanied with acoustic emission (AE) registration and full-field strain measurement on the surface. The test produces stress–strain diagrams and identifies characteristic strain levels for post-mortem investigation: just after first damage ε1; well-developed damage ε2; just before the final fracture of the sample ε3. Full-field strain measurement highlights the relation between strain concentrations (linked with the damage initiation) and the reinforcement structure. (2) Samples loaded up to ε1. . .3 are examined with CT and X-ray. This reveals the damage pattern and allows quantitative characterising of the damage development. (3) Optical and SEM examination of cross-sections through the damage sites, determined with X-ray, identifies local damage modes. The same strain levels are further used for setting up fatigue tests. The experimental protocol is applied for triaxial braided and quasi-UD composites.status: publishe
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
Optical manipulation for studies of collisional dynamics of micron-sized droplets under gravity
A new experimental technique for creating and imaging collisions of
micron-sized droplets settling under gravity is presented. A pair of glycerol
droplets is suspended in air by means of two optical traps. The droplet
relative velocities are determined by the droplet sizes. The impact parameter
is precisely controlled by positioning the droplets using the two optical
traps. The droplets are released by turning off the trapping light using
electro-optical modulators. The motion of the sedimenting droplets is then
captured by two synchronized high-speed cameras, at a frame rate of up to 63
kHz. The method allows the direct imaging of the collision of droplets without
the influence of the optical confinement imposed by the trapping force. The
method will facilitate efficient studies of the microphysics of neutral, as
well as charged, liquid droplets and their interactions with light, electric
field and thermodynamic environment, such as temperature or vapor
concentration.Comment: 13 pages, 8 figures, 1 tabl
Vortex solitons in dispersive nonlinear Kerr type media
We have investigated the nonlinear amplitude vector equation governing the
evolution of optical pulses in optical and UV region. We are normalizing this
equation for the cases of different and equal transverse and longitudinal size
of optical pulses, of week and strong dispersion. This gives us the possibility
to reduce the amplitude equation to different nonlinear evolution equations in
the partial cases. For some of these nonlinear equations exact vortex solutions
are found. Conditions for experimental observations of these vortices are
determined.Comment: 28 pages, 9 figures, Late
Quantum internal modes of solitons in 1d easy-plane antiferromagnet in strong magnetic field
In presence of a strong external magnetic field the dynamics of solitons in a
one-dimensional easy-plane Heisenberg antiferromagnet exhibits a number of
peculiarities. Dynamics of internal soliton degrees of freedom is essentially
quantum, and they are strongly coupled to the "translational" mode of soliton
movement. These peculiarities lead to considerable changes in the response
functions of the system which can be detected experimentally.Comment: 8 pages, RevTeX, 6 figures, uses psfig.sty, submitted to PR
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