1,444 research outputs found
Reparametrization-Invariant Path Integral in GR and "Big Bang" of Quantum Universe
The reparametrization-invariant generating functional for the unitary and
causal perturbation theory in general relativity in a finite space-time is
obtained. The region of validity of the Faddeev-Popov-DeWitt functional is
studied. It is shown that the invariant content of general relativity as a
constrained system can be covered by two "equivalent" unconstrained systems:
the "dynamic" (with "dynamic" evolution parameter as the metric scale factor)
and "geometric" (given by the Levi-Civita type canonical transformation to the
action-angle variables where the energy constraint converts into a new
momentum). "Big Bang", the Hubble evolution, and creation of matter fields by
the "geometric" vacuum are described by the inverted Levi-Civita (LC)
transformation of the geomeric system into the dynamic one. The particular case
of the LC transformations are the Bogoliubov ones of the particle variables
(diagonalizing the dynamic Hamiltonian) to the quasiparticles (diagonalizing
the equations of motion). The choice of initial conditions for the "Big Bang"
in the form of the Bogoliubov (squeezed) vacuum reproduces all stages of the
evolution of the Friedmann-Robertson-Walker Universe in their conformal
(Hoyle-Narlikar) versions.Comment: 21 pages, latex, 4 figures in postscrip
Description of Supernova Data in Conformal Cosmology without Cosmological Constant
We consider cosmological consequences of a conformal invariant formulation of
Einstein's General Relativity where instead of the scale factor of the spatial
metrics in the action functional a massless scalar (dilaton) field occurs which
scales all masses including the Planck mass. Instead of the expansion of the
universe we get the Hoyle-Narlikar type of mass evolution, where the
temperature history of the universe is replaced by the mass history. We show
that this conformal invariant cosmological model gives a satisfactory
description of the new supernova Ia data for the effective magnitude - redshift
relation without a cosmological constant and make a prediction for the
high-redshift behavior which deviates from that of standard cosmology for
.Comment: 13 pages, 1 figure, includes discussion of SN1997ff, text revise
Sarma phase in relativistic and non-relativistic systems
We investigate the stability of the Sarma phase in two-component fermion
systems in three spatial dimensions. For this purpose we compare
strongly-correlated systems with either relativistic or non-relativistic
dispersion relation: relativistic quarks and mesons at finite isospin density
and spin-imbalanced ultracold Fermi gases. Using a Functional Renormalization
Group approach, we resolve fluctuation effects onto the corresponding phase
diagrams beyond the mean-field approximation. We find that fluctuations induce
a second order phase transition at zero temperature, and thus a Sarma phase, in
the relativistic setup for large isospin chemical potential. This motivates the
investigation of the cold atoms setup with comparable mean-field phase
structure, where the Sarma phase could then be realized in experiment. However,
for the non-relativistic system we find the stability region of the Sarma phase
to be smaller than the one predicted from mean-field theory. It is limited to
the BEC side of the phase diagram, and the unitary Fermi gas does not support a
Sarma phase at zero temperature. Finally, we propose an ultracold quantum gas
with four fermion species that has a good chance to realize a zero-temperature
Sarma phase.Comment: version published in Phys.Lett.B; 10 pages, 5 figure
On the relation between Bell inequalities and nonlocal games
We investigate the relation between Bell inequalities and nonlocal games by
presenting a systematic method for their bilateral conversion. In particular,
we show that while to any nonlocal game there naturally corresponds a unique
Bell inequality, the converse is not true. As an illustration of the method we
present a number of nonlocal games that admit better odds when played using
quantum resourcesComment: v3 changes: Updates to reflect PLA version. 1 examples changed.
Physics Letters A (accepted for publication
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