Nonperturbative Renormalisation Group: Applications to the few and many-body systems
School of Physics and Astronomy, University of
2 Institute for Theoretical and Experimental Physics, 117259, Moscow, Russia
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We consider the applications of functional renormalisation group to few and many-body systems. As an application to the few-body dynamics we study the ratio between the fermion-fermion scattering length and the dimer-dimer scattering length for systems of few nonrelativistic fermions. We ﬁnd a strong dependence on the cutoﬀ function used in the renormalisation ﬂow for a two-body truncation of the action. Adding a simple threebody term substantially reduces this dependence. In the context of many-body physics we study the dynamics of both symmetric and asymmetric many-fermion systems using the same functional renormalisation technique. It is demonstrated that functional renormalisation group gives sensible and reliable results and provides a solid theoretical ground for the future studies. Open questions as well as lines of further developments are discussed.
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