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T: Fachverband Teilchenphysik

T 8: Eingeladene Vorträge III

T 8.3: Eingeladener Vortrag

Donnerstag, 31. März 2011, 15:00–15:30, 30.21: 001

Non-perturbative Heavy Quark Effective Theory on the lattice — •Michele Della Morte — Institut fuer Kernphysik, Becherweg 45, Mainz

The b-quark is too heavy to be treated dynamically on the lattice. Indeed, in units of nowadays affordable resolutions am_b >> 1. A theoretically attractive option is to use effective theories like Heavy Quark Effective Theory (HQET), which provides the correct asymptotic description of QCD correlation functions in the limit m_b → ∞. Subleading effects are described by higher dimensional operators whose coupling constants are formally O(1/m_b) to the appropriate power. The degrees of freedom in the effective theory are strongly coupled and therefore a non-perturbative approach is needed. In addition HQET has to be matched to the full theory, a step, which must as well be performed non-perturbatively beyond leading order in 1/m_b.

A framework for non-perturbative HQET on the lattice has been recently introduced. In a first step we match HQET and QCD in a small volume (L=0.4 fm). To make contact with phenomenology the HQET expressions of the relevant quantities are then evolved to large volume. The essential tools in this step are the step scaling functions, which we introduce to describe the effects of a change in the linear size L of the system by a factor two. We present non-perturbative results at NLO in 1/m_b for the b-quark mass, the B_s spectrum and decay constant in the quenched approximation and with two dynamical flavors.