Two loop gluon condensate contributions to heavy quark current correlators: Exact results and approximations

Mar, 1994
9 pages
Published in:
  • Phys.Lett.B 329 (1994) 103-110
e-Print:
Report number:
  • OUT-4102-49,
  • INP-94-1-323,
  • BI-TP-94-02,
  • MPI-PHT-94-2

Citations per year

199420012008201520220246810
Abstract:
The coefficient functions of the gluon condensate G 2\langle G~2\rangle, in the correlators of heavy-quark vector, axial, scalar and pseudoscalar currents, are obtained analytically, to two loops, for all values of z=q 2/4m 2z=q~2/4m~2. In the limiting cases z0z\to0, z1z\to1, and zz\to-\infty, comparisons are made with previous partial results. Approximation methods, based on these limiting cases, are critically assessed, with a view to three-loop work. High accuracy is achieved using a few moments as input. A {\em single\/} moment, combined with only the {\em leading\/} threshold and asymptotic behaviours, gives the two-loop corrections to better than 1\% in the next 10 moments. A two-loop fit to vector data yields αsπG 20.021\langle\frac{\alpha_{\rm s}}{\pi}G~2\rangle\approx0.021GeV 4~4.
  • heavy quark
  • quark: current
  • correlation function
  • gluon: condensation
  • Feynman graph: higher-order
  • renormalization
  • numerical calculations