Highly improved staggered quarks on the lattice with applications to charm physics
Abstract
We use perturbative Symanzik improvement to create a new staggeredquark action (HISQ) that has greatly reduced oneloop tasteexchange errors, no treelevel order a^{2} errors, and no treelevel order (am)^{4} errors to leading order in the quark’s velocity v/c. We demonstrate with simulations that the resulting action has tasteexchange interactions that are 3 4 times smaller than the widely used ASQTAD action. We show how to bound errors due to taste exchange by comparing ASQTAD and HISQ simulations, and demonstrate with simulations that such errors are likely no more than 1% when HISQ is used for light quarks at lattice spacings of 1/10fm or less. The suppression of (am)^{4} errors also makes HISQ the most accurate discretization currently available for simulating c quarks. We demonstrate this in a new analysis of the ψη_{c} mass splitting using the HISQ action on lattices where am_{c}=0.43 and 0.66, with fullQCD gluon configurations (from MILC). We obtain a result of 111(5) MeV which compares well with the experiment. We discuss applications of this formalism to D physics and present our first highprecision results for D_{s} mesons.
 Publication:

Physical Review D
 Pub Date:
 March 2007
 DOI:
 10.1103/PhysRevD.75.054502
 arXiv:
 arXiv:heplat/0610092
 Bibcode:
 2007PhRvD..75e4502F
 Keywords:

 11.15.Ha;
 12.38.Aw;
 12.38.Gc;
 Lattice gauge theory;
 General properties of QCD;
 Lattice QCD calculations;
 High Energy Physics  Lattice
 EPrint:
 21 pages, 8 figures, 5 tables