Abstract
Abstract
Following the recent analysis done in collaboration with Jason Aebischer and Christoph Bobeth, I summarize the optimal, in our view, strategy for the present evaluation of the ratio ε
′/ε in the Standard Model. In particular, I emphasize the importance of the correct matching of the long-distance and short-distance contributions to ε
′/ε, which presently is only achieved by RBC-UKQCD lattice QCD collaboration and by the analytical Dual QCD approach. An important role play also the isospin-breaking and QED effects, which presently are best known from chiral perturbation theory, albeit still with a significant error. Finally, it is essential to include NNLO QCD corrections in order to reduce unphysical renormalization scheme and scale dependences present at the NLO level. Here µ
c
in m
c
(µ
c
) in the case of QCD penguin contributions and µ
t
in m
t
(µ
t
) in the case of electroweak penguin contributions play the most important roles. Presently the error on ε
′/ε is dominated by the uncertainties in the QCDP parameter
B
6
(
1
/
2
)
and the isospin-breaking parameter
Ω
^
eff
. We present a table illustrating this.
Subject
General Physics and Astronomy
Cited by
1 articles.
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