Titres et résumés

Sylvain Maillot
3-orbifolds with positive scalar curvature
I will present results on the question of which compact orientable 3-dimensional orbifolds admit a metric of positive scalar curvature (PSC). In particular I will show that there exists a family of 3-orbifolds with free fundamental group which are not PSC, a phenomenon that does not exist for 3-manifolds.
This is joint work with L. Bessières, I. Mondello and T. Richard.

Francesca Oronzio
Harmonic functions in noncompact 3-manifolds with non-negative scalar curvature
In this talk, we describe some monotonicity formulas holding along the regular level sets of suitable harmonic functions in complete, noncompact, one-ended 3-manifolds, whose topology is sufficiently simple, with nonnegative scalar curvature and with minimal, compact, connected boundary if the boundary is present. Using such the formulas, we obtain a simple proof of the celebrated positive mass theorem and a capacity-to-area inequality. This talk is based on some results obtained by a collaboration with V. Agostiniani and L. Mazzieri, and on a work in progress.