The Oktay–Kronfeld (OK) action extends the Fermilab improvement program for massive Wilson fermions to higher order in suitable power-counting schemes. It includes dimension-six and -seven operators necessary for matching to QCD through order O(ΛQCD3/mQ3) in HQET power counting, for applications to heavy–light systems, and O (v6) in NRQCD power counting, for applications to quarkonia. In the Symanzik power counting of lattice gauge theory near the continuum limit, the OK action includes all O (a2) and some O (a3) terms. To assess whether the theoretical improvement is realized in practice, we study combinations of heavy–strange and quarkonia masses and mass splittings, designed to isolate heavy-quark discretization effects. We find that, with one exception, the results obtained with the tree-level-matched OK action are significantly closer to the continuum limit than those obtained with the Fermilab action. The exception is the hyperfine splitting of the bottom–strange system, for which our statistical errors are too large to draw a firm conclusion. These studies are carried out with data generated with the tadpole-improved Fermilab and OK actions on 500 gauge configurations from one of MILC’s a≈ 0.12 fm, Nf= 2 + 1 -flavor, asqtad-staggered ensembles.
Bibliographical noteFunding Information:
Acknowledgements J.A.B. is supported by the Basic Science Research Program of the National Research Foundation of Korea (NRF) funded by the Ministry of Education (No. 2015024974). This project is supported in part by the U.S. Department of Energy under Grant No. DE-FC02-12ER-41879 (C.D.) and the U.S. National Science Foundation under Grant No. PHY14-14614 (C.D.). A.S.K. is supported in part by the German Excellence Initiative and the European Union Seventh Framework Programme under Grant Agreement No. 291763 as well as the European Union’s Marie Curie COFUND program. This manuscript has been co-authored by an employee of Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The research of W.L. is supported by the Creative Research Initiatives Program (No. 20160004939) of the NRF grant funded by the Korean government (MEST). W.L. would like to acknowledge the support from KISTI supercomputing center through the strategic support program for the supercomputing application research (No. KSC-2014-G3-003). Further computations were carried out on the DAVID GPU clusters at Seoul National University.
© 2017, The Author(s).
All Science Journal Classification (ASJC) codes
- Engineering (miscellaneous)
- Physics and Astronomy (miscellaneous)