Found 3 result(s)

18.02.2021 (Thursday)

OPE for form factors

Regular Seminar Amit Sever (Tel Aviv U.)

16:00 QMW
room zoom

We propose an operator product expansion for planar form factors of local operators in N = 4 SYM theory. This expansion is based on the dual conformal symmetry of these objects or, equivalently, the conformal symmetry of their dual description in terms of periodic Wilson loops. A form factor is decomposed into a sequence of known pentagon transitions and a new universal object that we call the “form factor transition”. This transition is subject to a set of non-trivial bootstrap constraints, which allows us to bootstrap it at any value of the coupling. We evaluate the form factor transition for MHV form factors of the chiral half of the stress tensor supermultiplet at leading order in perturbation theory and use it to produce OPE predictions at any loop order. We match the one-loop and two-loop predictions with data available in the literature. [for zoom link contact jung-wook(dot)kim(at)qmul(dot)ac(dot)uk]

08.02.2018 (Thursday)

S-matrix bootstrap for large N confining gauge theories

Exceptional Seminar Amit Sever (Tel-Aviv University)

13:00 KCL
room S -2.23

In the talk I'll consider theories of weakly interacting higher spin particles in flat spacetime. We will focus on the four-point scattering amplitude at high energies and imaginary scattering angles. Both, the leading asymptotic of the amplitude and the first sub-leading correction in this regime turn out to be universal. The leading asymptotic is equal to the corresponding limit of the Veneziano amplitude. We will compute the first sub-leading correction using a model of relativistic strings with massive endpoints and argue that it is unique using holography, the effective theory of long strings and bootstrap techniques.

07.02.2018 (Wednesday)

Scattering Amplitudes -- Wilson Loops Duality for the first non-planar correction

Triangular Seminar Amit Sever (CERN)

17:30 City U.
room A130

We study non-planar corrections to gluon scattering amplitudes in N = 4 SYM theory. In this talk, we focus on the first correction. It is computed by the double trace amplitude and is suppressed by one power of 1/Nc with respect to the leading single trace contribution. We extend the duality between planar scattering amplitudes and null polygonal Wilson loops to the double trace amplitude. The new duality allows us to extend the notion of loop integrand beyond the planar limit and to determine it using recursion relation. It also allows us to apply the integrability pentagon approach to the first non-planar order. We shortly discuss higher orders in the 't Hooft 1/Nc expansion.