4 research outputs found
Alpha_s from the Lattice Potential
We present an extensive study on the direct determination of the running
coupling alpha_s from the static quark antiquark force at short distances, in
quenched QCD. We find from our high statistics potential analysis that alpha_qq
exhibits two-loop asymptotic behaviour for momenta as low as .5 GeV. As a
result, we determine the zero flavour Lambda-parameter to be Lambda^0_MSBAR =
0.630(38)\sqrt{\sigma} = 293(18)^{+25}_{-63} MeV. A rough estimate of full QCD
effects leads to the five flavour value alpha_MSBAR(m_Z) = .102^{+6}_{-11}. A
comparison with other lattice results is made.Comment: 6 pages (LaTeX) with 7 postscript figures (epsf required), Invited
talk by K. Schilling held at Lattice '93 conference, Dallas, T
Can a Logarithmically Running Coupling Mimic a String Tension?
It is shown that a Coulomb potential using a running coupling slightly
modified from the perturbative form can produce an interquark potential that
appears nearly linear over a large distance range. Recent high-statistics SU(2)
lattice gauge theory data fit well to this potential without the need for a
linear string-tension term. This calls into question the accuracy of string
tension measurements which are based on the assumption of a constant
coefficient for the Coulomb term. It also opens up the possibility of obtaining
an effectively confining potential from gluon exchange alone.Comment: 13 pages, LaTeX, two figures not included, available from author.
revision - Line lengths fixed so it will tex properl