Matching the electroweak penguins q7, q8 and spectral correlators
Exact analytical expressions for the ∆S = 1 coupling Im GE in terms of observable spectral functions are given. This coupling determines the size of the ∆I = 3/2 contribution to ε′ . We show analytically how the scheme-dependence and scale dependences vanish to all orders in 1/Nc and NLO in αS explicitly both for Q7 and Q8 . Numerical results are derived for both Q7 and Q8 from the τ-data and know
