Articles

07/09/1993-- 07/09/1993

The impact of Stieltjes' work on continued fractions and orthogonal polynomials

Stieltjes' work on continued fractions and the orthogonal polynomials related to continued fraction expansions is summarized and an attempt is made to describe the influence of Stieltjes' ideas and work in research done after his death, with an emphasis on the theory of orthogonal polynomials.
Walter Van Assche
11/28/2011-- 11/18/2011

A remark on the ARE between Wilcoxon's and van~der~Waerden's scores

This paper is concerned with a comparison of van der Waerden's and Wilcoxon's scores.
Nadir Maaroufi Camille Sabbah Yvik Swan Thomas Verdebout
07/06/2015-- 06/01/2015

Cayley transforms of su(2) representations

Cayley rational forms for rotations are given as explicit spin matrix polynomials for any j. The results are compared to the Curtright-Fairlie-Zachos matrix polynomials for rotations represented as exponentials.
T. S. Van Kortryk
02/15/2018-- 02/15/2018

On the $L^p$ norm of the torsion unction

Bounds are obtained for the $L^p$ norm of the torsion function $v_{\Omega}$, i.e. the solution of $-\Delta v=1,\, v\in H_0^1(\Omega),$ in terms of the Lebesgue measure of $\Omega$ and the principal eigenvalue $\lambda_1(\Omega)$ of the Dirichlet Laplacian acting in $L^2(\Omega)$. We show that these bounds are sharp for $1\le p\le 2$.
Michiel van den Berg Thomas Kappeler
03/20/2003-- 03/20/2003

Formation and Evolution of Compact Stellar X-ray Sources

In this chapter we review the formation and evolution of compact binaries with neutron star and/or black hole components (i.e. LMXBs, HMXBs, binary pulsars). After an introduction we discuss stellar evolution in binaries and the processes involved in the mass-transfer phases of close binaries (RLO, CE, ang.mom.loss) with radiative/convective hydrogen or helium donor stars. We also describe the effects of accretion, asymmetric SN and systems merging as a result of gravitational wave radiation.
Thomas M. Tauris Ed van den Heuvel
07/09/1999-- 07/06/1999

Local-energy density functionals for an N-dimensional electronic system in a magnetic field

We present a general approach for the construction of the exact local-energy-density functionals for a uniform N-dimensional electronic system in a magnetic field. For arbitrary dimension, we obtain explicit expressions for the matter, kinetic, and exchange density functionals. In the zero-field limit, we recover the usual N-dimensional Thomas-Fermi theory. As an application of our results, we develop a current-density-functional theory, in the spirit of the Thomas-Fermi-Dirac approximation, for an inhomogeneous many-electron system in a magnetic field.
B. P. van Zyl
08/21/2000-- 08/21/2000

Van Hove Singularities in the Quark-Gluon Plasma

General arguments as well as different approximations for the in-medium quark propagator in a quark-gluon plasma lead to quark dispersion relations that exhibit a minimum in one branch (plasmino). This minimum causes Van Hove singularities in the dilepton production rate and mesonic correlators, which might have observable consequences.
Markus H. Thoma
11/21/2011-- 11/14/2011

On classical de Sitter solutions in higher dimensions

We derive necessary criteria for the existence of classical, meta-stable, de Sitter solutions in flux compactifications of type II supergravity down to dimensions higher than four. We find that the possibilities in higher dimensions are much more restricted than in four dimensions. The only models that satisfy the criteria are derived from O6 compactifications to D=5,6 and O5 compactifications to D=5 and no meta-stable solutions can exist in dimensions higher than six. All these models have in common that the compact dimensions are negatively curved.
Thomas Van Riet
04/17/2018-- 04/03/2018

What if string theory has no de Sitter vacua?

We present a brief overview of attempts to construct de Sitter vacua in string theory and explain how the results of this 20-year endeavor could point to the fact that string theory harbors no de Sitter vacua at all. Making such a statement is often considered controversial and "bad news for string theory". We discuss how perhaps the opposite can be true.
Ulf H. Danielsson Thomas Van Riet
05/19/2020-- 05/19/2020

Smearing orientifolds in flux compactifications can be OK

We present explicit examples of supergravity solutions corresponding to backreacting localised (non-intersecting) O6 planes in flux reductions of massive IIA supergravity and address some criticism towards the very existence of such solutions. We verify in detail how the smeared orientifold solution becomes a good approximation to the localised solution in the large volume/weak coupling limit, as expected. We also find an exotic solution where prior to backreaction the internal space has a boundary and when backreaction is included the boundary disappears and the space closes off. The exotic example is however outside of the supergravity approximation everywhere.
Stephanie Baines Thomas Van Riet


with thanks to arxiv.org/