Domain decomposition improvement of quark propagator estimation

Abstract

Applying domain decomposition to the lattice Dirac operator and the associated quark propagator, we arrive at expressions which, with the proper insertion of random sources therein, can provide improvement to the estimation of the propagator. Schemes are presented for both open and closed (or loop) propagators. In the end, our technique for improving open contributions is similar to the ``maximal variance reduction'' approach of Michael and Peisa, but contains the advantage, especially for improved actions, of dealing directly with the Dirac operator. Using these improved open propagators for the Chirally Improved operator, we present preliminary results for the static-light meson spectrum. The improvement of closed propagators is modest: on some configurations there are signs of significant noise reduction of disconnected correlators; on others, the improvement amounts to a smoothening of the same correlators.Comment: 19 pages, 8 figures, version to appear in Computer Physics Communication

Radial and orbital excitations of static-light mesons

“…The static-light excited-state spectrum in dynamical QCD has previously been studied in Refs. [20,21].…”

B-meson spectroscopy in HQET at order1/m

“…CDF has claimed the observation of a resonant state B(5970) that may be interpreted as a B 0 state [16]. Lattice predictions for the radial excitation energies of the B system have been made in the framework of NRQCD [17,18] and HQET [19][20][21][22][23][24][25][26][27], but, with the exception of the most recent HQET studies, control of the continuum extrapolation has been limited, if possible at all. An additional difficulty that always needs to be addressed is in disentangling single particle excitations from multiparticle states.…”

B meson excitations with chirally improved light quarks

“…It will also be interesting to watch the 2S − 1S splitting (holding thus far ∼ 650 − 700 MeV for m q ≈ m s ; see also [1]) as we proceed to higher statistics and finer lattice spacing.…”

“…This so-called "domain decomposition improvement" was outlined and tested in Ref. [1] and amounts to a variant of the "maximal variance reduction" approach [2]. We present the basics of the method here.…”