String Theory Seminars

Thursday, November 9, 2017
from
to
(Asia/Kolkata)

at A 304

at A 304

Description |
Chern-Simons theories coupled to matter have a wide variety of applications ranging from anyonic physics to quantum gravity via the AdS/CFT correspondence. These theories enjoy a strong-weak duality that has been tested to a very good accuracy via large N computations. Scattering amplitudes are some of the most basic observables in QFT’s. S matrices computed to all orders in the ’t Hooft coupling serve as important testing grounds for the strong-weak duality. Although beginning with 4 point amplitudes this is doable, the complexity of the problem increases with the number of external legs. As a first step towards computing all loop arbitrary n point amplitudes, we address the problem of computing arbitrary n point tree level amplitudes. We show that BCFW recursion relations can be used to compute all tree level scattering amplitudes in terms of 2 → 2 scattering amplitude in U(N) N = 2 Chern- imons (CS) theory coupled to matter in fundamental representation. As a byproduct, we also obtain a recursion relation for the CS theory coupled to regular fermions, even though in this case standard BCFW deformations do not have a good asymptotic behavior. We then proceed to take the first steps towards all loop computations of arbitrary n point amplitudes. As a first step we explain the result of arXiv:1505.06571, where it was shown that the 2 → 2 scattering is tree level exact to all orders except in the anyonic channel, where it gets renormalized by a simple function of ’t Hooft coupling. We show that tree level 2 ! 2 scattering amplitudes in 3d N = 2 Chern-Simons theory coupled to a fundamental chiral multiplet are dual superconformal invariant. We further show that the large N all loop exact amplitude also has dual superconformal symmetry, which implies dual superconformal symmetry is all loop exact which is in contrast to other known highly supersymmetric examples such as N = 4 SYM and ABJM where the dual superconformal symmetry is in general anomalous The presence of superconformal and dual superconformal symmetry indicate the existence of a Yangian symmetry, further providing indications that the N=2 theory may be integrable. |