Darmstadt 2016 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 31: Hauptvorträge I

HK 31.1: Invited Talk

Wednesday, March 16, 2016, 11:00–11:30, S1/01 A1

Extracting two- and three-particle resonances from the lattice — •Maxwell Hansen — Helmholtz Institut Mainz, Mainz, Germany

The theory of the strong force, QCD, is non-perturbative at low energies. For this reason, numerical techniques are needed to extract the low-lying resonance spectrum from the underlying theory. Lattice QCD offers a numerically tractable non-perturbative method that can be systematically improved to reach reliable physical predictions. However, numerical lattice calculations are necessarily performed in a finite volume and with Euclidean time coordinates. This greatly complicates the calculation of scattering amplitudes, which are needed to study resonances. In this talk I discuss formalism that circumvents these issues, allowing one to rigorously extract scattering observables and determine resonance widths and masses. The approach, based on early work from Martin Lüscher, is to us the finite-volume energy spectrum as the lattice observable, and then map it via non-perturbative formal relations to the desired scattering amplitudes. I will summarize the formal work of Lüscher and its modern extensions and also give examples of how the method has been applied in state-of-the-art calculations.