Invitation to the Joint ICTP-SISSA Webinar Colloquium by Prof. Anton Alekseev, Université de Genève, on Wednesday 17 March 2021 at 16:00 hrs.

[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

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

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

*Biosketch: *please follow the link: 
https://www.unige.ch/math/en/people/alekseev/

*Abstract: *Integration by localisation in finite and infinite 
dimensions 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 asum 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.

The talk will be followed by a question/answer session

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