1,478 research outputs found
Inflation on Fractional Branes: D--Brane Inflation as D--Term Inflation
We describe a D--brane inflation model which consists of two fractional D3
branes separated on a transverse . Inflation arises due to the
resolved orbifold singularity of which corresponds to an anomalous D--term
on the brane. We show that D--brane inflation in the bulk corresponds to
D--term inflation on the brane. The inflaton and the trigger field parametrize
the interbrane distances on an respectively. After inflation the
branes reach a supersymmetric configuration in which they are at the origin of
but separated along the directions.Comment: 15 pages in phyzzx.tex; minor corrections including all factors of
2\pi; v3: more minor correction
The Inflaton and Time in the Matter-Gravity System
The emergence of time in the matter-gravity system is addressed within the
context of the inflationary paradigm. A quantum minisuperspace-homogeneous
minimally coupled inflaton system is studied with suitable initial conditions
leading to inflation and the system is approximately solved in the limit for
large scale factor. Subsequently normal matter (either non homogeneous inflaton
modes or lighter matter) is introduced as a perturbation and it is seen that
its presence requires the coarse averaging of a gravitational wave function
(which oscillates at trans-Planckian frequencies) having suitable initial
conditions. Such a wave function, which is common for all types of normal
matter, is associated with a ``time density'' in the sense that its modulus is
related to the amount of time spent in a given interval (or the rate of flow of
time). One is then finally led to an effective evolution equation (Schroedinger
Schwinger-Tomonaga) for ``normal'' matter. An analogy with the emergence of a
temperature in statistical mechanics is also pointed out.Comment: 14 pages, late
Proton-neutron quadrupole interactions: an effective contribution to the pairing field
We point out that the proton-neutron energy contribution, for low multipoles
(in particular for the quadrupole component), effectively renormalizes the
strength of the pairing interaction acting amongst identical nucleons filling
up a single-j or a set of degenerate many-j shells. We carry out the
calculation in lowest-order perturbation theory. We perform a study of this
correction in various mass regions. These results may have implications for the
use of pairing theory in medium-heavy nuclei and for the study of pairing
energy corrections to the liquid drop model when studying nuclear masses.Comment: 19 pages, TeX, 3 tables, 2 figures. Accepted in PR
Emotional eating is related with temperament but not with stress biomarkers in preschool children.
Emotional eating (EE) corresponds to a change in eating behavior in response to distress and results in an increase of food intake (overeating (EOE)) or in food avoidance (undereating (EUE)). EE has been related to temperament (i.e. negative emotionality) and dysregulated stress biomarkers in school-aged children; parenting has been understood to influence this relationship in older children. The aim of the study was to investigate to which extent stress biomarkers and negative emotionality are related to EE and to understand the role of parenting in this relationship. The sample consisted of 271 children aged 2-6 years of the Swiss cohort study SPLASHY. We assessed the child's EE, negative emotionality and parenting by parent based reports. Salivary samples were collected over two days to analyze cortisol and salivary alpha-amylase levels. From the whole sample of children, 1.1% showed EOE and 32.9% EUE. Negative emotionality was related to EOE and EUE (0.13 (CI 0.06, 021), p < 0.001; 0.25 (CI 0.14, 0.35), p < 0.001). There was no relationship between stress biomarkers and EE and parenting had any moderating role (all p > 0.05). Similar to a Danish study, parents reported more often EUE than EOE of their child. Both are related to the temperament. Even though the course of EE has not yet been well documented, we conclude that a certain subgroup of children with difficult temperament could be at-risk for eat and weight regulation problems in later childhood
Generation and dynamics of large scale flows in magnetized plasmas and rotating fluids (Invited paper)
Fluctuations of the Gravitational Constant Induced by Primordial Bubbles
We consider the classical fluctuations of the gravitational constant
generated by bubbles in the inflationary universe. For extended inflation, we
demonstrate numerically how and how large fluctuations are produced during
bubble expansion. The amplitude of the fluctuations depends on the Brans-Dicke
parameter : if is of the order of unity, the amplitude becomes
of the order of unity within one Hubble expansion time; if is large
(say, ), the growth rate of the fluctuations is small, but it
keeps growing without freezing during inflation. We also discuss some
astrophysical implications of our results.Comment: 8 pages, revtex, postscript figures, some comments are corrected, to
appear in Phys. Rev.
Monopole Inflation in Brans-Dicke Theory
According to previous work, topological defects expand exponentially without
an end if the vacuum expectation value of the Higgs field is of the order of
the Planck mass. We extend the study of inflating topological defects to the
Brans-Dicke gravity. With the help of numerical simulation we investigate the
dynamics and spacetime structure of a global monopole. Contrary to the case of
the Einstein gravity, any inflating monopole eventually shrinks and takes a
stable configuration. We also discuss cosmological constraints on the model
parameters.Comment: 17 pages, revtex, including figures, discussions in more general
theories are added, to appear in Phys. Rev.
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