# Würzburg 2018 – wissenschaftliches Programm

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# T: Fachverband Teilchenphysik

## T 13: Theorie: QFT / Gittereichtheorie

### T 13.6: Vortrag

### Montag, 19. März 2018, 17:15–17:30, Z6 - SR 1.013

**Trans-cutoff scattering in theory of a Goldstone boson** — •Lukas Eisemann — LMU, Muenchen, Deutschland

In a model of a Nambu-Goldstone-type scalar, we consider 2 → *n* scattering processes with the CM-energy *E* distributed equally over the *n* final quanta. We work out the scaling with *n* of the tree-level cross sections for these processes. At trans-cutoff energies, perturbative unitarity is violated for 2 → *few*, while for *n* sufficiently large, the theory behaves perturbatively. The turning point *n*_{t}, which sets the boundary between in- and decreasing behaviour of the cross section with *n*, can be found in terms of the CM-energy *E*.

We then investigate whether the existence of the turning point *n*_{t} may indicate that, in trans-cutoff scattering, non-perturbative states, which correspond to certain classical solutions, play a role. We do so by checking whether the spatial extension of those classical solutions *R*(*E*) scales in the same way with *E* as does the wavelength λ(*E*) = *n*_{t}(*E*) / *E* of the final quanta in the scattering processes 2 → *n*_{t}.