7.07.20 15:15

Elastic scattering amplitudes and resonant transition matrix elements from Lattice QCD

Marcus Petschlies (HISKP)

Large-scale computer simulations of fields on a discretized, finite-volume lattice in Euclidean spacetime have become a powerful approach to the numerical solution of strongly coupled field theories.  Within the framework of the Standard Model of elementary particle physics, the primary example is Quantum Chromodynamics on the Lattice (LQCD): starting from the first principles of the strong interaction of quarks and gluons, we arrive at the non-perturbative description of the interaction of e.g. pions, kaons, and nucleons in the low-energy regime with systematically improvable precision.


The theoretical framework for calculating elastic scattering amplitudes on the lattice has been introduced already in the early days of LQCD, while profound hard- and software developments were required to reach the present-day level of versatility and precision in hadron spectroscopy.  Likewise, the determination of QCD-matrix elements for electro-weak processes has a long and successful history in LQCD.  However, the combination of both to extract matrix elements including unstable initial or final states has only recently been developed to access a larger class of processes and applied in LQCD calculations.  It opens a new vast field for the rigorous investigation of such transition amplitudes. Important examples for such processes are the radiative transitions π π → ρ → π γ or N π → ∆ → N γ.  In the colloquium I discuss the theoretical background and describe our practical approach to the calculation of elastic scattering amplitudes and of resonant "2 → 1" transitions, at the hand of several examples.


The talk will be given via Zoom or similar; details t.b.a.

Kategorie: Kolloquium, HISKP News