## strings@ar

XXXIII Encuentro de la red strings@ar.

Lunes 13 de octubre de 2008, IAFE

PROGRAMA

XXXIII Encuentro de la red strings@ar - Programa (póster para imprimir)

Lunes 13 de octubre de 2008

IAFE, Ciudad Universitaria, Buenos Aires09h50 - 10h00 Apertura 10h00 - 11h00 Juan Maldacena (IAS, Princeton)

Chern Simons matter theories in 2+1 dimensions with six supersymmetries and gravity11h00 - 11h30 Café 11h30 - 12h30 Carmen Núñez (IAFE, Buenos Aires)

Fusion rules and four-point functions in the SL(2,R) WZNW model12h30 - 14h00 Almuerzo 14h00 - 15h00 Harald Ita (UCLA, Los Angeles)

The No-Triangle Hypothesis and unexpected cancellations in gravity theories15h00 - 15h30 Café 15h30 - 16h30 Alan Garbarz (UBA, Buenos Aires)

A boundary stress tensor for Topologically Massive Gravity

Juan Maldacena (IAS, Princeton)

Chern Simons matter theories in 2+1 dimensions with six supersymmetries and gravity

We consider a Chern Simons matter theory in 2+1 dimensions with six supercharges. This theory is related to N M2 branes on an R^{8}/Z_{k}singularity. We realize this theory as the low energy limit of some brane system and we explain how it is related to M2 branes. This gives us an example of AdS_{4}/CFT_{3}with a tunable coupling constant.

Harald Ita (UCLA, Los Angeles)

The No-Triangle Hypothesis and unexpected cancellations in gravity theories

Recent computations of scattering amplitudes show thatN=8 supergravity is surprisingly well behaved in the ultraviolet and may even be ultraviolet finite in perturbation theory. The novel cancellations necessary for ultraviolet finiteness first appear at one loop in the guise of the "no-triangle hypothesis". We will consider one-loop amplitudes inN=8 supergravity and discuss the "no-triangle hypothesis". We will then turn to one-loop amplitudes in pure Einstein gravity and point out the existence of cancellations similar to those found previously inN=8 supergravity. These cancellations go beyond those found in the one-loop effective action. Using unitarity, this suggests that generic theories of quantum gravity based on the Einstein-Hilbert action may be better behaved in the ultraviolet at higher loops than suggested by naive power counting, though without additional (supersymmetric) cancellations they diverge.