# Heidelberg 2015 – wissenschaftliches Programm

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# SYEP: Symposium Efimov Physics

## SYEP 2: Symposium Efimov Physics II

### SYEP 2.1: Hauptvortrag

### Montag, 23. März 2015, 14:30–15:00, C/gHS

**Efimov Physics from Quantum Field Theory** — •Eric Braaten — Ohio State University, Columbus, USA

The quantum-field-theory formulation of the problem of identical bosons interacting through a large scattering length provides deep insights into Efimov physics. In this approach, the zero-range limit is taken exactly, and the consequent short-distance singularities are dealt with using renormalization. The renormalization is governed by an ultraviolet limit cycle, which is reflected in low-energy physics through a 3-body parameter upon which physical observables can only depend log-periodically. In few-body physics, this feature can be exploited to obtain remarkable analytic results for some 3-body observables. One implication for many-body physics is that the momentum distribution approaches its asymptotic form C/k^4 at large momentum k though a subleading D(k)/k^5 term with a log-periodic coefficient. This effect may have been observed in recent experiments on the unitary Bose gas.