25,764 research outputs found
Soekarno: His Mannerism and Method of Communication
The main purpose of this article is to discuss Soekarno\u27s mannerism and method of communication. Certain aspects such as Soekarno\u27s use of language in his speeches are highlighted here in order to provide some basic understanding of Soekarno - both as a person and a political leader of the nation. The article aims at stimulating further discussions concerning this very well known leader. This article also examines Soeharto\u27s style of speech for a comparison
The transition temperature of the dilute interacting Bose gas for internal degrees of freedom
We calculate explicitly the variation of the Bose-Einstein
condensation temperature induced by weak repulsive two-body interactions
to leading order in the interaction strength. As shown earlier by general
arguments, is linear in the dimensionless product
to leading order, where is the density and the scattering length. This
result is non-perturbative, and a direct perturbative calculation of the
amplitude is impossible due to infrared divergences familiar from the study of
the superfluid helium lambda transition. Therefore we introduce here another
standard expansion scheme, generalizing the initial model which depends on one
complex field to one depending on real fields, and calculating the
temperature shift at leading order for large . The result is explicit and
finite. The reliability of the result depends on the relevance of the large
expansion to the situation N=2, which can in principle be checked by systematic
higher order calculations. The large result agrees remarkably well with
recent numerical simulations.Comment: 10 pages, Revtex, submitted to Europhysics Letter
The asymmetric ABAB matrix model
In this letter, it is pointed out that the two matrix model defined by the
action S=(1/2)(tr A^2+tr B^2)-(alpha_A/4) tr A^4-(alpha_B/4) tr B^4-(beta/2)
tr(AB)^2 can be solved in the large N limit using a generalization of the
solution of Kazakov and Zinn-Justin (who considered the symmetric case
alpha_A=alpha_B). This model could have useful applications to 3D Lorentzian
gravity.Comment: 7 pages, 1 figur
Unified Treatment of Even and Odd Anharmonic Oscillators of Arbitrary Degree
We present a unified treatment, including higher-order corrections, of
anharmonic oscillators of arbitrary even and odd degree. Our approach is based
on a dispersion relation which takes advantage of the PT-symmetry of odd
potentials for imaginary coupling parameter, and of generalized quantization
conditions which take into account instanton contributions. We find a number of
explicit new results, including the general behaviour of large-order
perturbation theory for arbitrary levels of odd anharmonic oscillators, and
subleading corrections to the decay width of excited states for odd potentials,
which are numerically significant.Comment: 5 pages, RevTe
Generating Scale-Invariant Perturbations from Rapidly-Evolving Equation of State
Recently, we introduced an ekpyrotic model based on a single, canonical
scalar field that generates nearly scale invariant curvature fluctuations
through a purely "adiabatic mechanism" in which the background evolution is a
dynamical attractor. Despite the starkly different physical mechanism for
generating fluctuations, the two-point function is identical to inflation. In
this paper, we further explore this concept, focusing in particular on issues
of non-gaussianity and quantum corrections. We find that the degeneracy with
inflation is broken at three-point level: for the simplest case of an
exponential potential, the three-point amplitude is strongly scale dependent,
resulting in a breakdown of perturbation theory on small scales. However, we
show that the perturbative breakdown can be circumvented -- and all issues
raised in Linde et al. (arXiv:0912.0944) can be addressed -- by altering the
potential such that power is suppressed on small scales. The resulting range of
nearly scale invariant, gaussian modes can be as much as twelve e-folds, enough
to span the scales probed by microwave background and large scale structure
observations. On smaller scales, the spectrum is not scale invariant but is
observationally acceptable.Comment: 42 pages, 1 figur
Constraining renormalon effects in lattice determination of heavy quark mass
The Borel summation technique of infrared renormalons is applied to the
lattice determination of heavy quark mass. With Borel summation a physical
heavy quark pole mass and binding energy of a heavy-light meson can be defined
in a rigorous and calculable manner. A notable feature of the Borel summation,
compared to the usual perturbative cancellation of IR renormalons, is an
automatic scale separation. The two approaches of handling renormalon
divergence are compared in the B-meson as well as in an (imaginary) heavy-light
meson with a mass much larger than the inverse of the lattice spacing.Comment: References and NNLO analysis added. Version to appear in Phys Rev
Symmetric path integrals for stochastic equations with multiplicative noise
A Langevin equation with multiplicative noise is an equation schematically of
the form dq/dt = - F(q) + e(q) xi, where e(q) xi is Gaussian white noise whose
amplitude e(q) depends on q itself. I show how to convert such equations into
path integrals. The definition of the path integral depends crucially on the
convention used for discretizing time, and I specifically derive the correct
path integral when the convention used is the natural, time-symmetric one that
time derivatives are (q_t - q_{t-\Delta t}) / \Delta t and coordinates are (q_t
+ q_{t-\Delta t}) / 2. [This is the convention that permits standard
manipulations of calculus on the action, like naive integration by parts.] It
has sometimes been assumed in the literature that a Stratanovich Langevin
equation can be quickly converted to a path integral by treating time as
continuous but using the rule \theta(t=0) = 1/2. I show that this prescription
fails when the amplitude e(q) is q-dependent.Comment: 8 page
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