943 research outputs found
The origin of scale-scale correlations of the density perturbations during inflation
We show that scale-scale correlations are a generic feature of slow-roll
inflation theories. These correlations result from the long-time tails
characteristic of the time dependent correlations because the long wavelength
density perturbation modes are diffusion-like. A relationship between the
scale-scale correlations and time-correlations is established providing a way
to reveal the time correlations of the perturbations during inflation. This
mechanism provides for a testable prediction that the scale-scale correlations
at two different spatial points will vanish.Comment: Accepted for publication, International Journal of Modern Physics,
vol. 8 No.6 (Dec 1999
A relativistic calculation of super-Hubble suppression of inflation with thermal dissipation
We investigated the evolution of the primordial density perturbations
produced by inflation with thermal dissipation. A full relativistic analysis on
the evolution of initial perturbations from the warm inflation era to a
radiation-dominated universe has been developed. The emphasis is on tracking
the ratio between the adiabatic and the isocurvature mode of the initial
perturbations. This result is employed to calculate a testable factor: the
super-Hubble suppression of the power spectrum of the primordial perturbations.
We show that based on the warm inflation scenario, the super-Hubble suppression
factor, , for an inflation with thermal dissipation is at least 0.5. This
prediction does not depend on the details of the model parameters. If is
larger than 0.5, it implies that the friction parameter is larger than
the Hubble expansion parameter during the inflation era.Comment: 22 pages, 3 figures, use RevTex, accepted by Class. Quant. Gra
Generalized metarationalities in the graph model for conflict resolution
AbstractA metarational tree is defined within the graph model for conflict resolution paradigm, providing a general framework within which rational behavior in models with two decision makers (DMs) can be described more comprehensively. A new definition of stability for a DM that depends on the total number, h, of moves and counter-moves allowed is proposed. Moreover, the metarational tree can be refined so that all moves must be unilateral improvements, resulting in a new set of stability definitions for each level of the tree. Relationships among stabilities at various levels of the basic and refined trees are explored, and connections are established to existing stability definitions including Nash stability, general metarationality, symmetric metarationality, sequential and limited-move stability, and policy equilibria
Protoplanetary Disks in Ophiuchus as Seen From ALMA
We present a high angular resolution (), high
sensitivity ( mJy) survey of the 870 m continuum emission
from the circumstellar material around 49 pre-main sequence stars in the
Ophiuchus molecular cloud. Because most millimeter instruments have resided in
the northern hemisphere, this represents the largest high-resolution,
millimeter-wave survey of the circumstellar disk content of this cloud. Our
survey of 49 systems comprises 63 stars; we detect disks associated with 29
single sources, 11 binaries, 3 triple systems and 4 transition disks. We
present flux and radius distributions for these systems; in particular, this is
the first presentation of a reasonably complete probability distribution of
disk radii at millimeter-wavelengths. We also compare the flux distribution of
these protoplanetary disks with that of the disk population of the
Taurus-Auriga molecular cloud. We find that disks in binaries are both
significantly smaller and have much less flux than their counterparts around
isolated stars. We compute truncation calculations on our binary sources and
find that these disks are too small to have been affected by tidal truncation
and posit some explanations for this. Lastly, our survey found 3 candidate
gapped disks, one of which is a newly identified transition disk with no
signature of a dip in infrared excess in extant observations.Comment: 26 pages, 16 figures. Accepted for publication in Ap
Theory of control of optomechanical transducers for quantum networks
We present a scheme of control for the arbitrary optical interface mediated by a nanoscale mechanical oscillator between flying qubits and optical nonactive solid-state qubits. This quantum interface lays the foundation for many key functions of a quantum network, such as transferring, swapping, and entangling qubits between distant nodes of a quantum network. Numerical simulations of the quantum interface operations show high fidelities and robust tolerance under realistic experimental conditions. Compared with a previous scheme, it may significantly increase the speed of state transfer operation of high fidelity
Environmental Effect on the Associations of Background Quasars with Foreground Objects: II. Numerical Simulations
Using numerical simulations of cluster formation in the standard CDM model
(SCDM) and in a low-density, flat CDM model with a cosmological constant
(LCDM), we investigate the gravitational lensing explanation for the reported
associations between background quasars and foreground clusters. Under the
thin-lens approximation and the unaffected background hypothesis , we show that
the recently detected quasar overdensity around clusters of galaxies on scales
of arcminutes cannot be interpreted as a result of the gravitational
lensing by cluster matter and/or by their environmental and projected matter
along the line of sight, which is consistent with the analytical result based
on the observed cluster and galaxy correlations (Wu, et al. 1996). It appears
very unlikely that uncertainties in the modeling of the gravitational lensing
can account for the disagreement between the theoretical predictions and the
observations. We conclude that either the detected signal of the quasar-cluster
associations is a statistical fluke or the associations are are generated by
mechanisms other than the magnification bias.Comment: 15 pages, 5 figures, accepted for publication in Ap
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