945 research outputs found
Evolution of thick domain walls in inflationary and universe
We study the evolution of thick domain walls in the different models of
cosmological inflation, in the matter-dominated and radiation-dominated
universe, or more generally in the universe with the equation of state
. We have found that the domain wall evolution crucially depends on
the time-dependent parameter , where is the
Hubble parameter and is the thickness of the wall in flat
space-time. For the physical thickness of the wall, ,
tends with time to , which is microscopically small. Otherwise, when
, the wall steadily expands and can grow up to a cosmologically
large size.Comment: 15 pages, 9 figure
Entropy Balance and Dispersive Oscillations in Lattice Boltzmann Models
We conduct an investigation into the dispersive post-shock oscillations in
the entropic lattice-Boltzmann method (ELBM). To this end we use a root finding
algorithm to implement the ELBM which displays fast cubic convergence and
guaranties the proper sign of dissipation. The resulting simulation on the
one-dimensional shock tube shows no benefit in terms of regularization from
using the ELBM over the standard LBGK method. We also conduct an experiment
investigating of the LBGK method using median filtering at a single point per
time step. Here we observe that significant regularization can be achieved.Comment: 18 pages, 4 figures; 13/07/2009 Matlab code added to appendi
Suppression of decay channels in the Georgi-Machacek model
The decay mode is usually considered as one of the most promising
ways to discover new heavy neutral scalar . We show that in the
Georgi-Machacek model it is possible to get large enhancement of double SM-like
Higgs boson production due to decays while and decay channels
could be highly suppressed.Comment: 5 page
Extending the Higgs sector: an extra singlet
An extension of the Standard Model with an additional Higgs singlet is
analyzed. Bounds on singlet admixture in 125 GeV h boson from electroweak
radiative corrections and data on h production and decays are obtained.
Possibility of double h production enhancement at 14 TeV LHC due to heavy higgs
contribution is considered.Comment: 18 pages, 7 figures. v2: one equation added; references received
after the publication of v1 are adde
New Physics at 1 TeV?
If decays of a heavy particle S are responsible for the diphoton excess with
invariant mass 750 GeV observed at the 13 TeV LHC run, it can be easily
accomodated in the Standard Model. Two scenarios are considered: production in
gluon fusion through a loop of heavy isosinglet quark(s) and production in
photon fusion through a loop of heavy isosinglet leptons. In the second case
many heavy leptons are needed or/and they should have large electric charges in
order to reproduce experimental data on .Comment: 7 pages, 4 figures, 1 tabl
Spectral singularities and Bragg scattering in complex crystals
Spectral singularities that spoil the completeness of Bloch-Floquet states
may occur in non-Hermitian Hamiltonians with complex periodic potentials. Here
an equivalence is established between spectral singularities in complex
crystals and secularities that arise in Bragg diffraction patterns. Signatures
of spectral singularities in a scattering process with wave packets are
elucidated for a PT-symmetric complex crystal.Comment: 6 pages, 5 figures, to be published in Phys. Rev.
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