20,389 research outputs found
and mesons with NRQCD and Clover actions
We present preliminary results from our study of the heavy-light spectrum and
decay constants. For the heavy quark, we use NRQCD at various masses around and
above the quark mass. For the first time, the heavy quark action and the
heavy-light current consistently include corrections at second order in the
non-relativistic expansion, as well as the leading finite corrections. The
light quarks are simulated using a tadpole-improved Clover action at various
masses in the strange and quark region.Comment: 6 Pages LaTex. Axis files of figures included. Joint writeup of two
talks presented at LATTICE96(heavy quarks
Entropy of a generic null surface from its associated Virasoro algebra
Null surfaces act as one-way membranes, blocking information from those
observers who do not cross them (e.g., in the black hole and the Rindler
spacetimes) and these observers associate an entropy (and temperature) with the
null surface. The black hole entropy can be computed from the central charge of
an appropriately defined, local, Virasoro algebra on the horizon. We show that
one can extend these ideas to a general class of null surfaces, all of which
possess a Virasoro algebra and a central charge, leading to an entropy density
(i.e., per unit area) which is just . All the previously known results
of associating entropy with horizons arise as special cases of this very
general property of null surfaces demonstrated here and we believe this work
represents the derivation of the entropy-area law in the most general context.
The implications are discussed.Comment: v2, 7pp; added references, discussions and clarifications; improved
presentation; published in PL
Large q expansion of the 2D q-states Potts model
We present a recursive method to calculate a large q expansion of the 2d
q-states Potts model free energies based on the Fortuin-Kasteleyn
representation of the model. With this procedure, we compute directly the
ordered phase partition function up to order 10 in 1/sqrt{q}. The energy
cumulants at the transition can be obtained with suitable resummation and come
out large for q less or around 15. As a consequence, expansions of the free
energies around the transition temperature are useless for not large enough
values of q. In particular the pure phase specific heats are predicted to be
much larger, at q < 15, than the values extracted from current finite size
scaling analysis of extrema, whereas they agree very well with recent values
extracted at the transition point.Comment: 31 pages (tex) including 15 figures (Postscript
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