4,207 research outputs found
Two-dimensional Riemannian and Lorentzian geometries from second order ODEs
In this note we give an alternative geometrical derivation of the results
recently presented by Garcia-Godinez, Newman and Silva-Ortigoza in [1] on the
class of all two-dimensional riemannian and lorentzian metrics from 2nd order
ODEs which are in duality with the two dimensional Hamilton-Jacobi equation. We
show that, as it happens in the Null Surface Formulation of General Relativity,
the Wuschmann-like condition can be obtained as a requirement of a vanishing
torsion tensor. Furthermore, from these second order ODEs we obtain the
associated Cartan connections.Comment: 9 pages, final version to appear in J. Math. Phy
International liquidity swaps: is the Chiang Mai Initiative pooling reserves efficiently?
We analyze the network of bilateral liquidity swaps (BSAs) among the ASEAN+3 countries. We find that the network has taken the correlation of capital flows in the region into account, in the sense that countries with lower correlation of reserve growth have engaged in larger BSAs. All else equal, a decimal point increase in the correlation of international reserve growth decreases the size of a bilateral swap agreement between 18 and 27%. Moreover, we find that the approximatedly $ 60bn of BSAs have had a limited impact, if any, on government bond spreads so far. Finally, we identify potential gains from inter-regional BSAs
Equation of State of the Fermionic 2D Hubbard Model
We present results for the equation of state of the two-dimensional Hubbard
model on an isotropic square lattice as obtained from a controlled and
numerically exact large-cluster dynamical mean field simulation. Our results
are obtained for large but finite systems and are extrapolated to infinite
system size using a known finite size scaling relation. We present the energy,
entropy, double occupancy and nearest-neighbour spin correlations extrapolated
to the thermodynamic limit and discuss the implications of these calculations
on pseudogap physics of the 2D-Hubbard model away from half filling. We find a
strong behavioural shift in energy below a temperature which becomes more
pronounced for larger clusters. Finally, we provide reference calculations and
tables for the equation of state for values of doping away from half filling
which are of interest to cold atom experiments.Comment: 8 pages 6 figures - See Source for Supplementary Material File
International Liquidity Swaps : Is the Chiang Mai Initiative Pooling Reserves Efficiently ?
We analyze the network of bilateral liquidity swaps (BSAs) among the ASEAN+3 countries. We find that the network has taken the correlation of capital flows in the region into account, in the sense that countries with lower correlation of reserve growth have engaged in larger BSAs. All else equal, a decimal point increase in the correlation of international reserve growth decreases the size of a bilateral swap agreement between 18 and 27%. Moreover, we find that the approximatedly $ 60bn of BSAs have had a limited impact, if any, on government bond spreads so far. Finally, we identify potential gains from inter-regional BSAs.insurance ; international reserves ; liquidity ; sovereign risk ; swaps
The Information Metric on the moduli space of instantons with global symmetries
In this note we revisit Hitchin's prescription \cite{Hitchin} of the Fisher
metric as a natural measure on the moduli space of instantons that encodes the
space-time symmetries of a classical field theory. Motivated by the idea of the
moduli space of supersymmetric instantons as an emergent space in the sense of
the gauge/gravity duality, we extend the prescription to encode also global
symmetries of the underlying theory. We exemplify our construction with the
instanton solution of the sigma model on .Comment: 5 pages, no figures, sorr
Superconductivity and Pairing Fluctuations in the Half-Filled Two-Dimensional Hubbard Model
The two-dimensional Hubbard model exhibits superconductivity with d-wave
symmetry even at half-filling in the presence of next-nearest neighbor hopping.
Using plaquette cluster dynamical mean-field theory with a continuous-time
quantum Monte Carlo impurity solver, we reveal the non-Fermi liquid character
of the metallic phase in proximity to the superconducting state. Specifically,
the low-frequency scattering rate for momenta near (\pi, 0) varies
non-monotonously at low temperatures, and the dc conductivity is T-linear at
elevated temperatures with an upturn upon cooling. Evidence is provided that
pairing fluctuations dominate the normal-conducting state even considerably
above the superconducting transition temperature.Comment: 4.3 pages, 4 figure
opendf - an implementation of the dual fermion method for strongly correlated systems
The dual fermion method is a multiscale approach for solving lattice problems
of interacting strongly correlated systems. In this paper, we present the
\texttt{opendf} code, an open-source implementation of the dual fermion method
applicable to fermionic single-orbital lattice models in dimensions
and . The method is built on a dynamical mean field starting point, which
neglects all local correlations, and perturbatively adds spatial correlations.
Our code is distributed as an open-source package under the GNU public license
version 2.Comment: 7 pages, 6 figures, 28th Annual CSP Workshop proceeding
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