123488833
Scattering amplitudes in three-dimensional superconformal field theory
Recent progress in computation of loop amplitudes in three-dimensional superconformal models is reviewed.
119238771
Scattering in ABJ theories
A bstractWe study the correspondence between scattering amplitudes and Wilson loops in three-dimensional Chern-Simons matter theories. In particular, using $ \mathcal{N} = {2} $ superspace formalism, we compute at one loop the whole spectrum of four-point superamplitudes for generic $ \mathcal{N} \geqslant {2} $ supersymmetric theories and find a vanishing result for $ \mathcal{N} = {6} $ ABJ(M) and $ \mathcal{N} = {8} $ BLG models. This restricts the possible range of theories for which Wilson loops/scattering amplitudes duality might work. At two loops, we present the computation of the four-point ABJ scattering amplitude for external chiral superfields. Extending the known result for the ABJM Wilson loop to the ABJ case we find perfect agreement. We also discuss the dual conformal invariance of our results and the relationship between the Feynman diagram computation and unitarity methods. While for the ABJM theory dual conformally invariant integrals exactly reproduce the amplitude, for the ABJ case this happens only up to a residual constant depending on the parity-violating parameter. Finally we propose a BDS-like exponentiation for the amplitude based on an analogy with the four dimensional $ \mathcal{N} = {4} $ SYM case, and discuss its strong coupling dual counterpart.
102332810
Scattering amplitudes/Wilson loop duality in ABJM theory
A bstractFor $$ \mathcal{N} = 6 $$ superconformal Chern-Simons-matter theories in three dimensions, by a direct superspace Feynman diagram approach, we compute the two-loop four-point scattering amplitude with external chiral matter fields. We find that the result is in perfect agreement with the two-loop result for a light-like four-polygon Wilson loop. This is the first non-trivial evidence that an amplitudes/Wilson loop duality might work in three dimensions. Moreover, both the IR divergent and the finite parts of our two-loop result agree with a BDS-like ansatz for all-loop amplitudes where the scaling function is given in terms of the $$ \mathcal{N} = 4 $$ SYM one, according to the conjectured Bethe equations for ABJM. Consequently, we are able to make a prediction for the four-loop correction to the amplitude. We also discuss the dual conformal invariance of the two-loop result.
6821869
Duality symmetries in string theory
We review the status of duality symmetries in superstring theories. These discrete symmetries mark the striking differences between theories of pointlike objects and theories of extended objects. They prove to be very helpful in understanding non-perturbative effects in string theories. We will also briefly discuss the strange role played by open strings and their solitons in the emerging scenario.
53865790
Scattering higher spins off D-branes
A bstractWe study scattering amplitudes of higher spin closed-string states off D-branes. For states in the ‘first Regge trajectory’ we find remarkable simplifications both at tree level and at one loop. We discuss the high energy behavior in the Regge limit and comment on the validity of the eikonal approximation in this regime.
119112440
Perturbative and non-perturbative N=8 supergravity
Abstract We study extremal black holes, their ADM mass and area of the horizon in N = 8 supergravity. Contrary to intuition gained from N = 2 , 3 , 4 theories, in N = 8 , as well as in N = 5 , 6 , supergravity BPS states may become massless only at the boundary of moduli space. We show that stringy states described in Green, Ooguri, Schwarz (2007) [10] , which have no mass gap and survive in toroidal compactifications in addition to the massless states of perturbative N = 8 supergravity, display a null singularity in four-dimensional space–time, when viewed as solutions of the N = 8 version of Einstein equations. We analyze known methods of resolving such singularities and explain why they all fail in D = 4 , N = 8 supergravity. We discuss possible implications for the issue of UV finiteness of perturbative N = 8 supergravity and the plausibility of a non-perturbative completion that exclude singular states.
119438273
Instantons and Supersymmetry
The role of instantons in describing non-perturbative aspects of globally supersymmetric gauge theories is reviewed. The cases of theories with N = 1, N = 2 and N = 4 supersymmetry are discussed. Special attention is devoted to the intriguing relation between instanton solutions in field theory and branes in string theory.
117591378
Type I Vacua in the Web of String Dualities