Published November 1, 2005 | Version v1
Journal article

Υ spectrum and mb from full lattice QCD

  • 1. Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States)
  • 2. Department of Physics and Astronomy, University of Glasgow, Glasgow (United Kingdom)
  • 3. Laboratory of Elementary-Particle Physics, Cornell University, Ithaca, New York 14853 (United States)
  • 4. Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195 (United States)

Description

We show results for the Υ spectrum calculated in lattice QCD including for the first time vacuum polarization effects for light u and d quarks as well as s quarks. We use gluon field configurations generated by the MILC collaboration. The calculations compare the results for a variety of u and d quark masses, as well as making a comparison to quenched results (in which quark vacuum polarization is ignored) and results with only u and d quarks. The b quarks in the Υ are treated in lattice Nonrelativistic QCD through NLO in an expansion in the velocity of the b quark. We concentrate on accurate results for orbital and radial splittings where we see clear agreement with experiment once u, d and s quark vacuum polarization effects are included. This now allows a consistent determination of the parameters of QCD. We demonstrate this consistency through the agreement of the Υ and B spectrum using the same lattice bare b quark mass. A one-loop matching to continuum QCD gives a value for the b quark mass in full lattice QCD for the first time. We obtain mbMS(mbMS)=4.4(3) GeV. We are able to give physical results for the heavy quark potential parameters, r0=0.469(7) fm and r1=0.321(5) fm. Results for the fine structure in the spectrum and the Υ leptonic width are also presented. We predict the Υ-ηb splitting to be 61(14) MeV, the Υ'-ηb' splitting as 30(19) MeV and the splitting between the hb and the spin-average of the χb states to be less than 6 MeV. Improvements to these calculations that will be made in the near future are discussed

Additional details

Publishing Information

Journal Title
Physical Review. D, Particles Fields
Journal Volume
72
Journal Issue
9
Journal Page Range
p. 094507-094507.25
ISSN
0556-2821
CODEN
PRVDAQ

Optional Information

Notes
(c) 2005 The American Physical Society
Collaborations
HPQCD and UKQCD Collaborations