4,235 research outputs found
ND Tadpoles as New String States and Quantum Mechanical Particle-Wave Duality from World-Sheet T-Duality
We consider new objects in bosonic open string theory -- ND tadpoles, which
have N(euman) boundary conditions at one end of the world-sheet and D(irichlet)
at the other, must exist due to s-t duality in a string theory with both NN
strings and D-branes. We demonstrate how to interpolate between N and D
boundary conditions. In the case of mixed boundary conditions the action for a
quantum particle is induced on the boundary. Quantum-mechanical particle-wave
duality, a dual description of a quantum particle in either the coordinate or
the momentum representation, is induced by world-sheet T-duality. The famous
relation between compactification radii is equivalent to the quantization of
the phase space area of a Planck cell. We also introduce a boundary operator -
a ``Zipper'' which changes the boundary condition from N into D and vice versa.Comment: 10 pages plain LateX2e, 4 eps figures included using epsf. Revised
version with extra reference
Boundary Logarithmic Conformal Field Theory
We discuss the effect of boundaries in boundary logarithmic conformal field
theory and show, with reference to both and models, how they
produce new features even in bulk correlation functions which are not present
in the corresponding models without boundaries. We discuss the modification of
Cardy's relation between boundary states and bulk quantities.Comment: 17 pages,3 eps figures, revised final section, clarification added in
a couple of other places, typos correcte
What does E_8 know about 11 dimensions ?
We discuss some possible relationships in gauge theories, string theory and M
theory in the light of some recent results obtained in gauge invariant
supersymmetric quantum mechanics. In particular this reveals a new relationship
between the gauge group E_8 and 11-dimensional space.Comment: 6 pages, Latex, no figure
Statistics of fluctuations for two types of crossover: from ballistic to diffusive regime and from orthogonal to unitary ensemble
In our previous publication [Kogan et al, Phys. Rev. {\bf 48}, 9404 (1993)]
we considered the issue of statistics of radiation diffusively propagating in a
disordered medium. The consideration was in the framework of diagrammatic
techniques and a new representation for the intensity distribution function in
terms of connected diagrams only was proposed. Here we use similar approach to
treat the issue of statistics in the regime of the crossover between ballistic
and diffusive transport. We find that even small contribution from coherent
component decreases by one half the intensity distribution function for small
values of intensity and also produces oscillations of the distribution
function. We also apply this method to study statistics of fluctuations of wave
functions of chaotic electrons in a quantum dot in an arbitrary magnetic field,
by calculating the single state local density in the regime of the crossover
between the orthogonal and unitary ensemble.Comment: Revtex, 3 pages + 2 ps.figures in uuencoded file, a version which
clarifies and unites the results of two previous submission
Dynamical chaos in the problem of magnetic jet collimation
We investigate dynamics of a jet collimated by magneto-torsional
oscillations. The problem is reduced to an ordinary differential equation
containing a singularity and depending on a parameter. We find a parameter
range for which this system has stable periodic solutions and study
bifurcations of these solutions. We use Poincar\'e sections to demonstrate
existence of domains of regular and chaotic motions. We investigate transition
from periodic to chaotic solutions through a sequence of period doublings.Comment: 11 pages, 29 figures, 1 table, MNRAS (published online
Time delay between the optical and X-ray outbursts in the high mass X-ray transient A0535+26/HDE245770
The optical behaviour of the Be star in the high mass X-ray transient
A0535+26/HDE245770 shows that at the periastron typically there is an
enhancement in the luminosity of order 0.02 to few tenths mag, and the X-ray
outburst happens about 8 days after the periastron. We construct a quantitative
model of this event, basing on the a nonstationary accretion disk behavior,
connected with a high ellipticity of the orbital motion. The ephemeris used in
this paper -- JD = JD(2,444,944) n(111.0 0.4)
days are derived from the orbital period of the system P days, determined by Priedhorsky & Terrell (1983), and from the optical
flare of December 5, 1981 (Giovannelli et al., 1985) (here after 811205-E; E
stands for the Event occurred at that date) that triggered the subsequent X-ray
outburst of December 13, 1981 (Nagase et al., 1982) (here after 811213-E). We
explain the observed time delay between the peaks of the optical and X-ray
outbursts in this system by the time of radial motion of the matter in the
accretion disk, after an increase of the mass flux in the vicinity of a
periastral point in the binary. This time is determined by the turbulent
viscosity, with the parameter . The increase of the mass flux
is a sort of flush that reaches the external part of the accretion disk around
the neutron star, producing an enhancement in the optical luminosity. The
consequent X-ray flare happens when the matter reaches the hot central parts of
the accretion disk, and the neutron star surface.Comment: 30 pages, 15 figures, with correction in abstrac
Durability of Output and Expected Stock Returns
The demand for durable goods is more cyclical than that for nondurable goods and services. Consequently, the cash flows and stock returns of durable-good producers are exposed to higher systematic risk. Using the benchmark input-output accounts of the National Income and Product Accounts, we construct portfolios of durable-good, nondurable-good, and service producers. In the cross-section, an investment strategy that is long on the durable-good portfolio and short on the service portfolio earns a risk premium exceeding 4 percent annually. In the time series, an investment strategy that is long on the durable-good portfolio and short on the market portfolio earns a countercyclical risk premium. We explain these findings in a general equilibrium asset-pricing model with endogenous production.
Analytic solution for kinetic equilibrium of beta-processes in nucleonic plasma with relativistic pairs
The analytic solution is obtained describing kinetic equilibrium of the
-processes in the nucleonic plasma with relativistic pairs. The nucleons
are supposed to be non-relativistic and non-degenerate, while the
electrons and positrons are ultra-relativistic due to high temperature
K), or high density g/cm), or both, where
is a number of nucleons per one electron. The consideration is simplified
because of the analytic connection of the density with the electron chemical
potential in the ultra-relativistic plasma, and Gauss representation of Fermi
functions. Electron chemical potential and number of nucleons per one initial
electron are calculated as functions of and .Comment: 16 pages, 6 figure
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