Week 19.10.2019 – 27.10.2019

Tuesday

TBA

Regular Seminar Bernd Braunecker (St. Andrews)

 at: 15:00 City U.room B104 abstract:

Wednesday

TBA

Regular Seminar Fischbacher Thomas (Google Research)

 at: 14:00 ICroom H503 abstract:

Differential equations for one-loop string integrals

Regular Seminar Oliver Schlotterer (Uppsala)

 at: 13:15 KCLroom S2.29 abstract: In this talk, I will describe new mathematical structures in the low-energy expansion of one-loop string amplitudes. The insertion of external states on the open- and closed-string worldsheets requires integration over punctures on a cylinder boundary and a torus, respectively. Suitable bases of such integrals will be shown to obey simple first-order differential equations in the modular parameter of the surface. These differential equations will be exploited to perform the integrals order by order in the inverse string tension, similar to modern strategies for dimensionally regulated Feynman integrals. Our method manifests the appearance of iterated integrals over holomorphic Eisenstein series in the low-energy expansion. Moreover, infinite families of Laplace equations can be generated for the modular forms in closed-string low-energy expansions.

Anomalous supersymmetry

Polygon Seminar Kostas Skenderis (University of Southampton)

 at: 15:00 QMWroom Bancroft 2.40 abstract: I will present an introduction to anomalies and then discuss the recently discovered anomalies for supersymmetry.

Thursday

Differential equations for one-loop string integrals

Regular Seminar Oliver Schlotterer (Uppsala University)

 at: 14:00 QMWroom G O Jones 610 abstract: In this talk, I will describe new mathematical structures in the low-energy expansion of one-loop string amplitudes. The insertion of external states on the open- and closed-string worldsheets requires integration over punctures on a cylinder boundary and a torus, respectively. Suitable bases of such integrals will be shown to obey simple first-order differential equations in the modular parameter of the surface. These differential equations will be exploited to perform the integrals order by order in the inverse string tension, similar to modern strategies for dimensionally regulated Feynman integrals. Our method manifests the appearance of iterated integrals over holomorphic Eisenstein series in the low-energy expansion. Moreover, infinite families of Laplace equations can be generated for the modular forms in closed-string low-energy expansions.