Dear B-Physics Friends,
we have a theory seminar tomorrow that might be interesting for some of you (please see details below).
Best regards,
Robert
Begin forwarded message:
From: Damien George dpgeorge@nikhef.nl Date: April 27, 2011 12:36:23 PM GMT+02:00 To: theory-wide@nikhef.nl Subject: [Theory-wide] Nikhef theory seminar -- Thursday 28th @ 2pm
Dear all,
Tomorrow we have a theory seminar at 2pm in room H331. The speaker is Michele Della Morte from Mainz. See below for details.
Regards, Damien George and Mert Aybat.
Date/place: Thursday 28th April, 2pm, H331 Speaker: Michele Della Morte (Mainz) Title: Non-perturbative Heavy Quark Effective Theory on the lattice
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 to infinity. 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.
We have introduced a framework for non-perturbative HQET on the lattice. 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_bfor the b-quark mass, the B_s spectrum and decay constant in the quenched approximation and with two dynamical flavors. Perspectives on other phenomenologically interesting quantities (as semileptonic form factors) are also discussed.
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