Eur. Phys. J. C 19, 681-691
DOI: 10.1007/s100520100598
Improving
and the charm mass
by analytic continuation
A.D. Martin1, J. Outhwaite1 and M.G. Ryskin1, 2
1 Department of Physics and Institute for Particle Physics Phenomenology, University of Durham, Durham, DH1 3LE
2 Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg, 188300, Russia
(Received: 19 December 2000 / Published online: 6 April 2001 -© Springer-Verlag 2001 )
Abstract
The standard determination of the QED coupling on the Z pole is performed using the
latest available
data for R. The direct application of analytic continuation techniques is found not to
improve the
accuracy of the value of
. However they
help to resolve an ambiguity in the values of R in the energy region
, which, in turn, reduces the uncertainty in
.
Moreover, they provide a sensitive determination of the mass of the
charm quark. The
favoured solution, which uses the inclusive data for R for
, has a pole mass
and
; whereas if the sum of the exclusive channels is used to determine R in
this region, we find
.
© Società Italiana di Fisica, Springer-Verlag 2001