Reminder: Today, Wednesday 17 March at 16:00 CET: Joint ICTP-SISSA Webinar Colloquium by Prof. Anton Alekseev, Université de Genève

[ICTP/director]

Dear All,

You are most cordially invited to the Joint ICTP-SISSA Webinar 
Colloquium by Prof. Anton Alekseev, Université de Genève, Switzerland 
<https://en.wikipedia.org/wiki/Anton_Alekseev_(mathematician)>,  on 
Wednesday 17 March 2021 at 16:00 hrs.

Pre-registration is required at the following url: 
https://sissa-it.zoom.us/webinar/register/WN_ePkh_5CvR3-30CJmzc_PyA

The talk will be available on livestream via the ICTP website, and also 
on ICTP's YouTube channel.

After registering, you will receive a confirmation email containing 
information about joining the webinar.

*Biosketch:* Anton Alekseev studied at the Leningrad State University 
and was trained at the Steklov Mathematical Institute in St. Petersburg 
where he obtained his PhD in Mathematical Physics in 1991. After 
research positions in Zurich and Uppsala, he became full professor for 
mathematics at the University of Geneva in 2001.

Alekseev has worked on a wide range of topics in mathematical physics 
and pure mathematics including algebra and geometry, as well as 
mechanics and field theory. He has made seminal contributions in these 
disciplines, and often his work uncovers connections and unexpected 
links between them.

*Talk abstract:*

Integral calculus is an art. One of the most surprising techniques in 
the calculation of multi-dimensional integrals is called localisation. 
In a typical example of localisation, an integral is presented as a sum 
of a finite number of simple contributions associated to fixed points of 
an action of a compact group (e.g. a circle) on the integration domain.

Localisation was discovered by Duistermaat and Heckman in their study of 
symplectic geometry of coadjoint orbits. They showed that certain 
oscillatory integrals can be computed exactly by taking the first two 
terms of their stationary phase expansion. Berline and Vergne, and 
Atiyah and Bott, gave a conceptual explanation of this phenomenon in 
terms of equivariant cohomology.

In this talk, we will start with some simple low dimensional examples, 
and then we will consider an infinite dimensional example of coadjoint 
orbits of the Virasoro algebra. Elements of Virasoro coadjoint orbits 
can be thought of as Schroedinger operators on the circle. Recently, 
Stanford and Witten considered formal Duistermaat-Heckman localisation 
formulas for the corresponding orbital integrals. If time permits, we 
will discuss possible mathematical interpretations of these formulas. 
(Based on a joint work with S. Shatashvili.)

For info, please check the following link: http://indico.ictp.it/event/9608/

We look forward to seeing you online!

With best regards,

Office of the Director, ICTP