4 research outputs found
Inflation without inflatons
(abridged)We present a model which predicts inflation without the presence of
inflaton fields, based on the \epsilon R^2 and Starobinsky models. It links the
above models to the observable universe, in particular, to the ratio r of
tensor to scalar fluctuations. In our model, we assume the existence of
particles with the mass M that have a long decay time. These particles which
were gravitationally produced \sim 60e-folds before the end of inflation
produced the nearly scale invariant scalar density fluctuations which are
observed. Gravitational waves (tensor fluctuations) were also produced at this
epoch. The ratio of tensor to scalar fluctuations r (which are to be measured
in the near future to good accuracy) determines M, which together with H_0,
determine the time at the end of inflation, t_end. At t_end, the Hubble
parameter begins to oscillate rapidly, gravitationally producing the bulk of
the M particles, which we identify with the matter content of the universe
today. The time required for the universe to dissipate its vacuum energy into M
particles is found to be t_dis \simeq 6M_Pl^2/M^3. We assume that the time
t_RH, (called the reheating time) needed for the M particles to decay into
relativistic particles, is very much greater than that necessary to create the
M particles, t_dis. From the ratio f\equiv t_dis/t_RH and g_\ast (the total
number of degrees of freedom of the relativistic particles) we can, then,
evaluate the maximum temperature of the universe, T_max, and the reheat
temperature, T_RH, at t_RH. Our model, thus, predicts M, t_dis, t_end, T_max,
T_RH, t_max, and t_RH as a function of r, f, and g_\ast (and to a weaker extent
the particle content of the vacuum near the Planck epoch).Comment: 11 pages, 2 figures. Revised version, accepted for publication in
Phys. Rev.
World-Sheet Duality, Space-Time Foam, and the Quantum Fate of a Stringy Black Hole
We interpret Minkowski black holes as world-sheet {\it spikes } which are
related by world-sheet { \it duality} to {\it vortices } that correspond to
Euclidean black holes. These world-sheet defects induce defects in the gauge
fields of the corresponding coset Wess-Zumino descriptions of
spherically-symmetric black holes. The low-temperature target space-time foam
is a Minkowski black hole (spike) plasma with confined Euclidean black holes
(vortices). The high-temperature phase is a {\it dense} vortex plasma described
by a topological gauge field theory on the world-sheet, which possesses
enhanced symmetry as in the target space-time singularity at the core of a
black hole. Quantum decay via higher-genus effects induces a back-reaction
which causes a Minkowski black hole to lose mass until it is indistinguishable
from intrinsic fluctuations in the space-time foam.Comment: 16 pages, CERN-TH.6534/92, (correction of a minor typographical error
on page 12
SNI: a new mechanism for gamma ray burst. I. Weak magnetic field
Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal