Nonperturbatively improved heavy-light mesons: Masses and decay constants

We present a study of the heavy-light spectrum and of the D- and B-meson decay constants. The results were obtained in the quenched approximation, by using the nonperturbatively improved clover lattice action at (Formula presented) with a sample of (Formula presented) configurations, on a (Formula presented) lattice. After a careful analysis of the systematic errors present in the extraction of the physical results, by assuming quite conservative discretization errors, we find (Formula presented) (Formula presented) (Formula presented) (Formula presented) (Formula presented) (Formula presented) Our results, which have smaller discretization errors than many previous estimates at fixed value of the lattice spacing a, support a large value of (Formula presented) in the quenched approximation. © 1999 The American Physical Society.