14,076 research outputs found
String theory extensions of Einstein-Maxwell fields: the static case
We present a new approach for generation of solutions in the four-dimensional
heterotic string theory with one vector field and in the five-dimensional
bosonic string theory starting from the static Einstein-Maxwell fields. Our
approach allows one to construct the solution classes invariant with respect to
the total subgroup of the three-dimensional charging symmetries of these string
theories. The new generation procedure leads to the extremal
Israel-Wilson-Perjes subclass of string theory solutions in a special case and
provides its natural continuous extension to the realm of non-extremal
solutions. We explicitly calculate all string theory solutions related to
three-dimensional gravity coupled to an effective dilaton field which arises
after an appropriate charging symmetry invariant reduction of the static
Einstein-Maxwell system.Comment: 19 pages in late
Charging Interacting Rotating Black Holes in Heterotic String Theory
We present a formulation of the stationary bosonic string sector of the whole
toroidally compactified effective field theory of the heterotic string as a
double Ernst system which, in the framework of General Relativity describes, in
particular, a pair of interacting spinning black holes; however, in the
framework of low--energy string theory the double Ernst system can be
particularly interpreted as the rotating field configuration of two interacting
sources of black hole type coupled to dilaton and Kalb--Ramond fields. We
clarify the rotating character of the --component of the
antisymmetric tensor field of Kalb--Ramond and discuss on its possible torsion
nature. We also recall the fact that the double Ernst system possesses a
discrete symmetry which is used to relate physically different string vacua.
Therefore we apply the normalized Harrison transformation (a charging symmetry
which acts on the target space of the low--energy heterotic string theory
preserving the asymptotics of the transformed fields and endowing them with
multiple electromagnetic charges) on a generic solution of the double Ernst
system and compute the generated field configurations for the 4D effective
field theory of the heterotic string. This transformation generates the
vector field content of the whole low--energy heterotic string
spectrum and gives rise to a pair of interacting rotating black holes endowed
with dilaton, Kalb--Ramond and multiple electromagnetic fields where the charge
vectors are orthogonal to each other.Comment: 15 pages in latex, revised versio
Induced inflation from a 5D purely kinetic scalar field formalism on warped product spaces
Considering a separable and purely kinetic 5D scalar field on a warped
product metric background we propose a new and more general approach for
inducing 4D scalar potentials on a 4D constant foliation of the 5D space-time.
We obtain an induced potential for a true 4D scalar field instead of a
potential for an effective 4D scalar field. In this formalism we can recover
the usual 4D inflationary formalism with a geometrically induced inflationary
potential. In addition the quantum confinement of the inflaton modes is
obtained naturally from the model for at least a class of warping factors.
Besides the 4D inflationary physics that results of this formalism is
independent of the 4D-hypersurface chosen.Comment: 8 pages Accepted for publication in European Physical Journal
Revisiting the composition dependence of the properties of water-dimethyl sulfoxide liquid mixtures. Molecular dynamics computer simulations
We have revisited the composition dependence of principal properties of
liquid water-DMSO mixtures by using the isobaric-isothermal molecular dynamics
computer simulations. A set of non-polarizable semi-flexible models for the
DMSO molecule combined with the TIP4P-2005 and TIP4P/ water models
is considered. We restrict calculations to atmospheric pressure, 0.1013 MPa,
and room temperature, 298.15 K. Composition trends of density, excess mixing
volume and excess mixing enthalpy, partial molar volumes and partial molar
enthalpies of species, apparent molar volumes are reported. Besides, we explore
composition trends of the self-diffusion of species, the static dielectric
constant and the surface tension. Evolution of the microscopic structure of the
mixture with composition is analyzed in terms of radial distributions
functions, coordination numbers and the fractions of hydrogen-bonded molecules.
We intend to capture the peculiarities of mixing the species in the mixture
upon the DMSO molar fraction and the anomalous behaviors, if manifested in each
of the properties under study. The quality of several combinations of the
models for species is evaluated in detail to establish the possibility of
necessary improvements.Comment: 19 pages, 11 figures, 1 tabl
Revisiting the wetting behavior of solid surfaces by water-like models within a density functional theory
We perform the analysis of predictions of a classical density functional
theory for associating fluids with different association strength concerned
with wetting of solid surfaces. The four associating sites water-like models
with non-associative square-well attraction parametrized by Clark et al. [Mol.
Phys., 2006, 104, 3561] are considered. The fluid-solid potential is assumed to
have a 10-4-3 functional form. The growth of water film on the substrate upon
changing the chemical potential is described. The wetting and prewetting
critical temperatures, as well as the prewetting phase diagram are evaluated
for different fluid-solid attraction strength from the analysis of the
adsorption isotherms. Moreover, the temperature dependence of the contact angle
is obtained from the Young equation. It yields estimates for the wetting
temperature as well. Theoretical findings are compared with experimental
results and in a few cases with data from computer simulations. The theory is
successful and quite accurate in describing the wetting temperature and contact
angle changes with temperature for different values of fluid-substrate
attraction. Moreover, the method provides an easy tool to study other
associating fluids on solids of importance for chemical engineering, in
comparison with laboratory experiments and computer simulations.Comment: 18 pages, 9 figure
Emergence of the pointer basis through the dynamics of correlations
We use the classical correlation between a quantum system being measured and
its measurement apparatus to analyze the amount of information being retrieved
in a quantum measurement process. Accounting for decoherence of the apparatus,
we show that these correlations may have a sudden transition from a decay
regime to a constant level. This transition characterizes a non-asymptotic
emergence of the pointer basis, while the system-apparatus can still be quantum
correlated. We provide a formalization of the concept of emergence of a pointer
basis in an apparatus subject to decoherence. This contrast of the pointer
basis emergence to the quantum to classical transition is demonstrated in an
experiment with polarization entangled photon pairs.Comment: 4+2 pgs, 3 figures. Title changed. Revised version to appear on PR
A hierarchy of bound states in the 1D ferromagnetic Ising chain CoNbO investigated by high resolution time-domain terahertz spectroscopy
Kink bound states in the one dimensional ferromagnetic Ising chain compound
CoNbO have been studied using high resolution time-domain terahertz
spectroscopy in zero applied magnetic field. When magnetic order develops at
low temperature, nine bound states of kinks become visible. Their energies can
be modeled exceedingly well by the Airy function solutions to a 1D
Schr\"odinger equation with a linear confining potential. This sequence of
bound states terminates at a threshold energy near two times the energy of the
lowest bound state. Above this energy scale we observe a broad feature
consistent with the onset of the two particle continuum. At energies just below
this threshold we observe a prominent excitation that we interpret as a novel
bound state of bound states -- two pairs of kinks on neighboring chains
EU External Relations: Exclusive Competence Revisited
This Article will focus on the question of exclusive competence in the field of EU external relations, especially in the light of recent developments. After a brief discussion on the origins and development of exclusive competence, a distinction will be made between common commercial policy, which has traditionally been the most important area of an explicit “a priori” exclusive competence, and what is often called an implicit exclusive competence, which, as it is today based on some general criteria enshrined in TFEU Article 3(2), may be called “supervening” exclusive competence. With regard to both categories, the main focus will be on recent developments, notably the impact of the Treaty of Lisbon, which introduced the TFEU and its Articles 2 and 3, as well as the case law of the European Court of Justice (“ECJ” or the “Court”) following the entry into force of the Treaty of Lisbon, on December 1, 2009
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