Twisted Pseudodifferential Calculus and Application to the Quantum Evolution of Molecules

Twisted Pseudodifferential Calculus and Application to the Quantum Evolution of Molecules
Author: AndrŽ Martinez
Publisher: American Mathematical Soc.
Total Pages: 96
Release: 2009-06-05
Genre: Mathematics
ISBN: 082184296X

The authors construct an abstract pseudodifferential calculus with operator-valued symbol, suitable for the treatment of Coulomb-type interactions, and they apply it to the study of the quantum evolution of molecules in the Born-Oppenheimer approximation, in the case of the electronic Hamiltonian admitting a local gap in its spectrum. In particular, they show that the molecular evolution can be reduced to the one of a system of smooth semiclassical operators, the symbol of which can be computed explicitely. In addition, they study the propagation of certain wave packets up to long time values of Ehrenfest order.

Generalized Noncrossing Partitions and Combinatorics of Coxeter Groups

Generalized Noncrossing Partitions and Combinatorics of Coxeter Groups
Author: Drew Armstrong
Publisher: American Mathematical Soc.
Total Pages: 176
Release: 2009-10-08
Genre: Mathematics
ISBN: 0821844903

This memoir is a refinement of the author's PhD thesis -- written at Cornell University (2006). It is primarily a desription of new research but also includes a substantial amount of background material. At the heart of the memoir the author introduces and studies a poset $NC^{(k)}(W)$ for each finite Coxeter group $W$ and each positive integer $k$. When $k=1$, his definition coincides with the generalized noncrossing partitions introduced by Brady and Watt in $K(\pi, 1)$'s for Artin groups of finite type and Bessis in The dual braid monoid. When $W$ is the symmetric group, the author obtains the poset of classical $k$-divisible noncrossing partitions, first studied by Edelman in Chain enumeration and non-crossing partitions.

Hypocoercivity

Hypocoercivity
Author: CŽdric Villani
Publisher: American Mathematical Soc.
Total Pages: 154
Release: 2009-10-08
Genre: Mathematics
ISBN: 0821844989

This memoir attempts at a systematic study of convergence to stationary state for certain classes of degenerate diffusive equations, taking the general form ${\frac{\partial f}{\partial t}}+ L f =0$. The question is whether and how one can overcome the degeneracy by exploiting commutators.

Yang-Mills Connections on Orientable and Nonorientable Surfaces

Yang-Mills Connections on Orientable and Nonorientable Surfaces
Author: Nan-Kuo Ho
Publisher: American Mathematical Soc.
Total Pages: 113
Release: 2009-10-08
Genre: Mathematics
ISBN: 0821844911

In ``The Yang-Mills equations over Riemann surfaces'', Atiyah and Bott studied Yang-Mills functional over a Riemann surface from the point of view of Morse theory. In ``Yang-Mills Connections on Nonorientable Surfaces'', the authors study Yang-Mills functional on the space of connections on a principal $G_{\mathbb{R}}$-bundle over a closed, connected, nonorientable surface, where $G_{\mathbb{R}}$ is any compact connected Lie group. In this monograph, the authors generalize the discussion in ``The Yang-Mills equations over Riemann surfaces'' and ``Yang-Mills Connections on Nonorientable Surfaces''. They obtain explicit descriptions of equivariant Morse stratification of Yang-Mills functional on orientable and nonorientable surfaces for non-unitary classical groups $SO(n)$ and $Sp(n)$.

Affine Insertion and Pieri Rules for the Affine Grassmannian

Affine Insertion and Pieri Rules for the Affine Grassmannian
Author: Thomas Lam
Publisher: American Mathematical Soc.
Total Pages: 103
Release: 2010
Genre: Mathematics
ISBN: 0821846582

The authors study combinatorial aspects of the Schubert calculus of the affine Grassmannian ${\rm Gr}$ associated with $SL(n,\mathbb{C})$.Their main results are: Pieri rules for the Schubert bases of $H^*({\rm Gr})$ and $H_*({\rm Gr})$, which expresses the product of a special Schubert class and an arbitrary Schubert class in terms of Schubert classes. A new combinatorial definition for $k$-Schur functions, which represent the Schubert basis of $H_*({\rm Gr})$. A combinatorial interpretation of the pairing $H^*({\rm Gr})\times H_*({\rm Gr}) \rightarrow\mathbb Z$ induced by the cap product.

Classification of Radial Solutions Arising in the Study of Thermal Structures with Thermal Equilibrium or No Flux at the Boundary

Classification of Radial Solutions Arising in the Study of Thermal Structures with Thermal Equilibrium or No Flux at the Boundary
Author: Alfonso Castro
Publisher: American Mathematical Soc.
Total Pages: 87
Release: 2010
Genre: Mathematics
ISBN: 0821847260

The authors provide a complete classification of the radial solutions to a class of reaction diffusion equations arising in the study of thermal structures such as plasmas with thermal equilibrium or no flux at the boundary. In particular, their study includes rapidly growing nonlinearities, that is, those where an exponent exceeds the critical exponent. They describe the corresponding bifurcation diagrams and determine existence and uniqueness of ground states, which play a central role in characterizing those diagrams. They also provide information on the stability-unstability of the radial steady states.

Topological Automorphic Forms

Topological Automorphic Forms
Author: Mark Behrens
Publisher: American Mathematical Soc.
Total Pages: 167
Release: 2010-02-22
Genre: Mathematics
ISBN: 082184539X

The authors apply a theorem of J. Lurie to produce cohomology theories associated to certain Shimura varieties of type $U(1,n-1)$. These cohomology theories of topological automorphic forms ($\mathit{TAF}$) are related to Shimura varieties in the same way that $\mathit{TMF}$ is related to the moduli space of elliptic curves.

Symplectic Actions of $2$-Tori on $4$-Manifolds

Symplectic Actions of $2$-Tori on $4$-Manifolds
Author: Alvaro Pelayo
Publisher: American Mathematical Soc.
Total Pages: 96
Release: 2010-02-22
Genre: Mathematics
ISBN: 0821847139

In this paper the author classifies symplectic actions of $2$-tori on compact connected symplectic $4$-manifolds, up to equivariant symplectomorphisms. This extends results of Atiyah, Guillemin-Sternberg, Delzant and Benoist. The classification is in terms of a collection of invariants of the topology of the manifold, of the torus action and of the symplectic form. The author constructs explicit models of such symplectic manifolds with torus actions, defined in terms of these invariants.