11 research outputs found
Inhomogeneous baryogenesis, cosmic antimatter, and dark matter
A model of inhomogeneous baryogenesis based on the Affleck and Dine mechanism
is described. A simple coupling of the scalar baryon field to the inflaton
allows for formation of astronomically significant bubbles with a large baryon
(or antibaryon) asymmetry. During the farther evolution these domains form
compact stellar-like objects, or lower density clouds, or primordial black
holes of different size. According to the scenario, such high baryonic number
objects occupy relatively small fraction of space but despite that they may
significantly contribute to the cosmological mass density. For some values of
parameters the model allows the possibility the whole dark matter in the
universe to be baryonic. Furthermore, the model allows the existence of the
antibaryonic B-bubbles, i.e. a significant fraction of the mass density in the
universe can be in the form of the compact antimatter objects (e.g.
anti-stars).Comment: 31 pages, 5 figures, three references are adde
Quantum back-reaction of the superpartners in a large-N supersymmetric hybrid model
We study the supersymmetric hybrid model near and after the end of inflation.
As usual, we reduce the model to a purely scalar hybrid model on the level of
the classical fields. But on the level of quantum fluctuations and their
backreaction we take into account all superpartners of the waterfall field in a
large-N approximation. The evolution after slow roll displays two phases with a
different characteristic behaviour of the classical and fluctuation fields. We
find that the fluctuations of the pseudoscalar superpartner are of particular
importance in the late time phase. The motion of the waterfall field towards
its classical expectation value is found to be very slow and suggests a rather
flat potential and a stochastic force.Comment: 37 pages 19 figure
Probing the last scattering surface through the recent and future CMB observations
We have constrained the extended (delayed and accelerated) models of hydrogen
recombination, by investigating associated changes of the position and the
width of the last scattering surface. Using the recent CMB and SDSS data, we
find that the recent data constraints favor the accelerated recombination
model, though the other models (standard, delayed recombination) are not ruled
out at 1- confidence level. If the accelerated recombination had
actually occurred in our early Universe, baryonic clustering on small-scales is
likely to be the cause of it. By comparing the ionization history of baryonic
cloud models with that of the best-fit accelerated recombination model, we find
that some portion of our early Universe has baryonic underdensity. We have made
the forecast on the PLANCK data constraint, which shows that we will be able to
rule out the standard or delayed recombination models, if the recombination in
our early Universe had proceeded with or lower, and
residual foregrounds and systematic effects are negligible.Comment: v2: matched with the accepted version (conclusions unchanged
Transmutations and spectral parameter power series in eigenvalue problems
We give an overview of recent developments in Sturm-Liouville theory
concerning operators of transmutation (transformation) and spectral parameter
power series (SPPS). The possibility to write down the dispersion
(characteristic) equations corresponding to a variety of spectral problems
related to Sturm-Liouville equations in an analytic form is an attractive
feature of the SPPS method. It is based on a computation of certain systems of
recursive integrals. Considered as families of functions these systems are
complete in the -space and result to be the images of the nonnegative
integer powers of the independent variable under the action of a corresponding
transmutation operator. This recently revealed property of the Delsarte
transmutations opens the way to apply the transmutation operator even when its
integral kernel is unknown and gives the possibility to obtain further
interesting properties concerning the Darboux transformed Schr\"{o}dinger
operators.
We introduce the systems of recursive integrals and the SPPS approach,
explain some of its applications to spectral problems with numerical
illustrations, give the definition and basic properties of transmutation
operators, introduce a parametrized family of transmutation operators, study
their mapping properties and construct the transmutation operators for Darboux
transformed Schr\"{o}dinger operators.Comment: 30 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1111.444
Transmutations for Darboux transformed operators with applications
We solve the following problem. Given a continuous complex-valued potential
q_1 defined on a segment [-a,a] and let q_2 be the potential of a Darboux
transformed Schr\"odinger operator. Suppose a transmutation operator T_1 for
the potential q_1 is known such that the corresponding Schr\"odinger operator
is transmuted into the operator of second derivative. Find an analogous
transmutation operator T_2 for the potential q_2.
It is well known that the transmutation operators can be realized in the form
of Volterra integral operators with continuously differentiable kernels. Given
a kernel K_1 of the transmutation operator T_1 we find the kernel K_2 of T_2 in
a closed form in terms of K_1. As a corollary interesting commutation relations
between T_1 and T_2 are obtained which then are used in order to construct the
transmutation operator for the one-dimensional Dirac system with a scalar
potential
Designing of Halbach cylinder based magnetic assembly for a rotating magnetic refrigerator. Part 1: Designing procedure
Generation of the alternating strong and almost zero homogeneous magnetic field that the
magnetocaloric material has to be exposed to is a major challenge in magnetic refrigeration.
With this paper we start a series of publications considering designing of Halbach cylinder
based magnet assemblies for non simultaneous cycles. In present, for the first part we define
a designing procedure which, applied to the Halbach cylinder, allows creation of two or higher
pole number magnet assemblies.We consider here two and four pole cases in great details.
Each designing procedure step is accompanied by 3D finite element simulation.The achieved
final magnet designs fulfill the predefined requirements of particular field distribution in
the air gap, maximized ratio of high field volume to the permanent magnet volume, best
utilization of magnets and magnetocaloric materials and constructional simplicity. A short
comparison of two and four pole arrangements is given
Initial time singularities and admissible initial states for a system of coupled scalar fields
We discuss the problem of initial states for a system of coupled scalar
fields out of equilibrium in the one-loop approximation. The fields consist of
classical background fields, taken constant in space, and quantum fluctuations.
If the initial state is the adiabatic vacuum, i.e., the ground state of a Fock
space of particle excitations that diagonalize the mass matrix, the
energy-momentum tensor is infinite at t=0, its most singular part behaves as
1/t. When the system is coupled to gravity this presents a problem that we
solve by a Bogoliubov transformation of the naive initial state. As a side
result we also discuss the canonical formalism and the adiabatic particle
number for such a system. Most of the formalism is presented for Minkowksi
space. Embedding the system and its dynamics into a flat FRW universe is
straightforward and we briefly address the essential modifications.Comment: 26 pages, no figures; typos corrected, added 6 paragraphs et the end
of section 3, and 1 paragraph at the end of section