Mathematics Problem Archive
Showing 1-27 of 27 problems
Soft Phases in Two-Dimensional O(N) Models
v1.3 research notesDo spin correlations in the classical Heisenberg model, and other $O(N)$ models with $N>2$, decay exponentially at every nonzero temperature, or do th...
Long-Range Order for the Quantum Heisenberg Model
v1.3 research notes(A) Prove long-range order for the quantum Heisenberg ferromagnet in dimension $D>2$ at temperature $T>0$. (B) Prove long-range order for spin $1/2$ i...
Extended States with Extensive Disorder
v1.3 research notesEstablish, in some energy range, the existence of extended eigenstates or continuous spectrum for linear operators with extensive disorder, such as a ...
One-Dimensional Fermi Gas with Attractive Interaction
v1.3 research notesDetermine the large-distance behavior of the one-particle reduced density matrix for a one-dimensional Fermi gas with spin and attractive interaction....
Entropy Production in Nonequilibrium Statistical Mechanics
v1.3 research notesGive a fundamental and experimentally accessible definition of the entropy creation rate for general classical systems in stationary nonequilibrium st...
Separatrix Splitting under Quasiperiodic Forcing
v1.3 research notesFind an asymptotic expression for the splitting of the separatrix of a quasiperiodically forced pendulum in the regime where the perturbation series i...
Meaning and Impossibility of Exact Helium Energy Levels
v1.3 research notesGive a mathematically precise meaning to determining the energy levels of the helium atom exactly, in the sense that hydrogen energy levels are exact,...
Absolutely Continuous Spectrum Under a Weighted L2 Condition
v1.3 research notesLet $V$ be a function on $\mathbb R^\nu$, $\nu\geq2$, satisfying $\int |x|^{-\nu+1}|V(x)|^2\,d^\nu x<\infty$. Prove that $-\Delta+V$ has absolutely co...
Bounded Excess Electrons
v1.3 research notesFor the $N$-electron Coulomb Hamiltonian with nuclear charge $Z$, let $N_0(Z)$ be the least $N$ after which adding electrons no longer lowers the grou...
First-Principles Molecular Configurations
v1.3 research notesGive a mathematically rigorous justification of the techniques used to determine molecular configurations from first principles....
Continuity of the Integrated Density of States
v1.3 research notesProve that the integrated density of states $k(E)$ is continuous as a function of the energy $E$....
One-Dimensional Lieb-Thirring Constants
v1.3 research notesFor spatial dimension $\nu=1$ and $1/2<\gamma<3/2$, determine the optimal constants $L_{\gamma,1}$ in the Lieb-Thirring inequality as predicted by the...
Riemann-Hilbert Problem with non-analytic data
v1.3 research notesIn many situations one is concerned with the asymptotic behavior of Riemann-Hilbert problems with exponentially varying data of the form $e^{in\phi(z)...
Multivariate analysis
v1.3 research notesRandom matrix theory was introduced into theoretical physics by Wigner in the 1950s in his study of neutron scattering resonances, but as a subject, R...
$\beta$-ensembles
v1.3 research notesRandom point processes corresponding to $\beta$-ensembles, or, equivalently, log gases at inverse temperature $\beta$, are defined for arbitrary $\bet...
Non-self adjoint spectral problems
v1.3 research notesMuch is now known, theoretically and also numerically, about the spectrum of self-adjoint operators. This is in great contrast to the situation regard...
Long-time behavior with non-generic initial data
v1.3 research notesThe long-time behavior of the solution of the Cauchy problem for a great many integrable systems on the line is now well-understood, using, for exampl...
The parking problem
v1.3 research notesA number of so-called ``transportation'' problems have now been analyzed in terms of RMT. These include: the ``vicious'' walker problem of M. Fisher, ...
The Toda lattice with random initial data
v1.3 research notesLet $J$ be a random tridiagonal matrix drawn from the tridiagonal Gaussian orthogonal ensemble and evolve it by the finite nonperiodic Toda flow, so i...
Perturbation theory for infinite dimensional integrable systems
v1.3 research notesThe bijective mapping properties of the scattering transform for a variety of integrable systems on the line between appropriate weighted Sobolev spac...
Initial/boundary value problems for integrable systems
v1.3 research notesIn the late 1990s Fokas introduced a new, more flexible approach to inverse scattering theory, and in recent years a number of researchers (Fokas, Its...
Multi-matrix models and models with an external field
v1.3 research notesThere has been considerable progress (Kuijlaars,...) in understanding basic statistics such as the correlation functions for the 2-matrix random matri...
KdV with almost periodic initial data
v1.3 research notesConsider the Korteweg--de Vries (KdV) equation u_t + u u_x + u_{xxx} =0 with initial data u(x, t=0) = u_0(x),\qquad x\in \mathbb{R}. In the 1970's, Mc...
interacting particle systems and KPZ
v1.3 research notesIn 1999, J. All these early examples were ``integrable'' in the sense that certain powerful algebraic tools, e.g., determinantal particle systems, the...
numerical computation with random data
v1.3 research notesStandard algorithms to compute the eigenvalues of a random matrix $H$ are completely integrable Hamiltonian systems (see ). The question raised in was...
initial boundary value problems for integrable systems (IBVP)
v1.3 research notesInitial boundary value problems for integrable systems in $1+1$ dimensions are of great interest. It turns out, however, that in Fokas' approach the g...
numerical solution of integrable systems
v1.3 research notesSolutions of the Cauchy problem for linear dispersive equations can be expressed in terms of Fourier integral operators. This is a very challenging pr...