Now showing items 1-10 of 35
The Picard group of the moduli space of curves with level structures
For 4 - L and g large, we calculate the integral Picard groups of the moduli spaces of curves and principally polarized abelian varieties with level L structures. In particular, we determine the divisibility properties of ...
Higher-Order Signature Cocycles for Subgroups of Mapping Class Groups and Homology Cylinders
(Oxford University Press, 2012)
The second rational homology group of the moduli space of curves with level structures
Let Γ be a finite-index subgroup of the mapping class group of a closed genus g surface that contains the Torelli group. For instance, Γ can be the level L subgroup or the spin mapping class group. We show that H2(Γ;Q) ∼= Q ...
Cubic fourfolds containing a plane and a quantic del Pezzo surface
(Foundation Compositio Mathematica, 2014)
We isolate a class of smooth rational cubic fourfolds X containing a plane whose associated quadric surface bundle does not have a rational section. This is equivalent to the nontriviality of the Brauer class β of the even ...
New Anomalous Lieb-Robinson Bounds in Quasiperiodic XY Chains
(American Physical Society, 2014)
We announce and sketch the rigorous proof of a new kind of anomalous (or sub-ballistic) Lieb-Robinson (LR) bound for an isotropic XY chain in a quasiperiodic transversal magnetic field. Instead of the usual effective light ...
Homology cobordism and Seifert fibered 3-manifolds
(American Mathematical Society, 2014)
It is known that every closed oriented 3-manifold is homology cobordant to a hyperbolic 3-manifold. By contrast we show that many homology cobordism classes contain no Seifert fibered 3-manifold. This is accomplished by ...
Wigner-von Neumann type perturbations of periodic Schrödinger operators
(American Mathematical Society, 2015)
Schrödinger operators on the half line. More precisely, the perturbations we consider satisfy a generalized bounded variation condition at infinity and an LP decay condition. We show that the absolutely continuous spectrum ...
On the unirationality of del Pezzo surfaces of degree two
(London Mathematical Society, 2014)
Among geometrically rational surfaces, del Pezzo surfaces of degree 2 over a field k containing at least one point are arguably the simplest that are not known to be unirational over k. Looking for k-rational curves on ...
Generators for the hyperelliptic Torelli group and the kernel of the Burau representation at t=−1
We prove that the hyperelliptic Torelli group is generated by Dehn twists about separating curves that are preserved by the hyperelliptic involution. This verifies a conjecture of Hain. The hyperelliptic Torelli group can ...