Nonperturbative Parameters for B-mixing from Lattice QCD

Welcome to the web pages of the B-mixing subgroup of the CKM Lattice Working Group. This group will consider B-meson decay constants, the B-mixing parameter B_B and the ratio xi.

A summary by Hartmut Wittig (EPS Conference, July 2003)

The experimental counterpart of this subgroup is the B mixing (oscillations) subgroup of the Heavy Flavour Averaging Group (HFAG):

Background

Since the literature on heavy-light decay constants and B_B is pretty vast, it may be useful to divide the task of compiling the data according to the various formulations used, i.e.

We could then form sub-groups which scan the literature for data using a particular formulation and compile the data tables. In the course of this the various criteria, which will be used to arrive (we hope) at a common estimate, should emerge as well. We recall that the CKM-LWG has already agreed only to use results from refereed publications. The advantage of this procedure would be that we can use the experience of our individual members in a particular formalism.

We should also consider the issue of correlations. One could certainly imagine that certain systematic effects will be correlated for calculations performed within a single formulation. We need to decide how to take this into account when trying to produce a single output number.

Here are some thoughts on what information to record:

• all cases
  • standard publication information, date, authors, collab, journal and archive reference, ...
  • number of dynamical flavours
  • continuum extrapolation and/or lattice spacings used
  • lattice volume(s)
  • heavy quark formulation
  • type of improvement of action and operators
  • type of matching to continuum
  • scale-setting
  • chiral extrapolation
  • is this result taken into account in reaching output number?
  • comments (eg result superseded by later work of same group, why result is not used in producing output number, ...)
• relativistic formulations
  • what range of heavy quark masses simulated
  • model ansatz for extrapolation to B-meson
• nrqcd
  • what order in 1/m included in action/operators
  • range of heavy masses
• fermilab
  • ...
• static
  • procedure for reliable isolation of ground state
  • ...

Organisation