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Chiral limit prediction for ε′/KK at NLO in 1/Nc

We report on a calculation of ε′K/εK at next-to-leading in the 1/Nc expansion and to lowest order in Chiral Perturbation Theory. We discuss the short-distance matching, the scale and scheme dependence as well as the long-distance short-distance matching. We include the two known chiral corrections to our result and discuss further order p4 corrections to it.

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

Chlorinated persistent organic pollutants and type 2 diabetes - A population-based study with pre- and post- diagnostic plasma samples

Background: Persistent organic pollutants (POPs) have been associated with type 2 diabetes (T2D), but causality is uncertain. Objective: Within longitudinal population-based data from northern Sweden, we assessed how POPs associated with T2D prospectively and cross-sectionally, and further investigated factors related to individual changes in POP concentrations. Methods: For 129 case-controls pair

QCD signatures of narrow graviton resonances in hadron colliders

We show that the characteristic p⊥ spectrum yields valuable information for the test of models for the production of narrow graviton resonances in the TeV range at LHC. Furthermore, it is demonstrated that in those scenarios the parton showering formalism agrees with the prediction of NLO matrix element calculations.

QCD isospin breaking in meson masses, decay constants and quark mass ratios

The procedure to calculate masses and matrix-elements in the presence of mixing of the basis states is explained in detail. We then apply this procedure to the two-loop calculation in Chiral Perturbation Theory of pseudoscalar masses and decay constants including quark mass isospin breaking. These results are used to update our analysis of Kℓ4 done previously and obtain a value of mu/md in additio

Scheme dependence of weak matrix elements in the 1/Nc expansion

We show how the scheme- and scale-dependence of the short-distance operator product expansion with four-quark operators can be correctly accounted for in the framework of the 1/Nc-expansion once the hadronization of two-quark currents has been fixed. We show formulas explicitly in the case of the BK-parameter. We then use them together with our earlier estimates of the long-distance effects. We co

Renormalization of chiral perturbation theory to order p6

The renormalization of chiral perturbation theory is carried out to next-to-next-to-leading order in the meson sector. We calculate the divergent part of the generating functional of Green functions of quark currents to O(p6) for chiral SU(n), involving one- and two-loop diagrams. The renormalization group equations for the renormalized low-energy constants of O(p6) are derived. We compare our res

Two-point functions at two loops in three flavour chiral perturbation theory *

The vector and axial-vector two-point functions are calculated to next-to-next-to-leading order in Chiral Perturbation Theory for three light flavours. We also obtain expressions at the same order for the masses, m2 π, m2 Κ and m2 η, and the decay constants, Fπ, FΚ and Fη. We present some numerical results after a simple resonance estimate of some of the new O(p6) constants.

Low energy constants from K(l4) form-factors

We have calculated the form-factors F and G in K → ππlν decays (K(l4)) to two-loop order in Chiral Perturbation Theory (ChPT). Combining this together with earlier two-loop calculations an updated set of values for the L(i)/(r), the ChPT constants at O(p4), is obtained. We discuss the uncertainties in the determination and the changes compared to previous estimates. (C) 2000 Elsevier Science B.V.

Kℓ4 form-factors and π - π scattering

The F and G form-factors of Kℓ4 and the quark condensates are calculated to O(p6) in Chiral Perturbation theory (CHPT). Full formulas are presented as much as possible. A full refit of most of the O(p4) CHPT parameters is done with a discussion of all inputs and underlying assumptions. We discuss the consequences for the vacuum expectation values, decay constants, pseudoscalar masses and π - π sca

A parametrization for K+ → π+π-e+ν

We discuss various models and chiral perturbation theory results for the K14 form factors F and G. We check to what extent a simple parametrization with a few parameters can be used to extract information from experiment.

The mesonic chiral lagrangean of order p6

We construct the effective chiral lagrangean for chiral perturbation theory in the mesonic even-intrinsic-parity sector at order p6. The lagrangean contains 112 in principle measurable + 3 contact terms for the general case of n light flavours, 90+4 for three and 53+4 for two flavours. The equivalence between equations of motion and field redefinitions to remove spurious terms in the lagrangeans i

The vector and scalar form factors of the pion to two loops

We calculate the vector and scalar form factors of the pion to two loops in Chiral Perturbation Theory. We estimate the unknown O(p6) constants using resonance exchange. We make a careful comparison to the available data and determine two O(p4) constants rather precisely, and two O(p6) constants less precisely. We also use Chiral Perturbation Theory to two loops to extract in a model-independent m

Matching the heavy vector meson theory

We show how to obtain a "heavy" meson effective lagrangian for the case where the number of heavy particles is not conserved. We apply the method in a simple example at tree level and perform then the reduction for the case of vector mesons in Chiral Perturbation Theory in a manifestly chiral invariant fashion. Some examples showing that "heavy" meson effective theory also reproduces the correct n

Double chiral logs

We determine the full structure of the leading (double-pole) divergences of O(p6) in the meson sector of chiral perturbation theory. The field theoretic basis for this calculation is described. We then use an extension of this result to determine the p6 contributions containing double chiral logarithms (L2), single logarithms times p4 constants (L × Lr i) and products of two p4 constants (Lr i × L

Chiral corrections to vector meson decay constants

We calculate the leading quark mass corrections of order mqlog(mq), mq and m3/2 q to the vector meson decay constants within heavy vector meson chiral perturbation theory. We discuss the issue of electromagnetic gauge invariance and the heavy mass expansion. Reasonably good fits to the observed decay constants are obtained.

Obtaining K → ππ from off-shell K → π amplitudes

We properly define off-shell K → π transition amplitudes and use them to extract information for on-shell K → ππ amplitudes within Chiral Perturbation Theory. At order p2 in the chiral expansion all three parameters of weak interaction can be determined. At order p4 we are able to fix eleven additional constants out of thirteen contributing to off-shell K → π transitions, which leaves four undeter

π → lνγ form factors at two-loop

Within Chiral Perturbation Theory (CHPT) we compute the form factors A, V and γ = A/V in the π → lνγ decay to O(p6). A and γ obtain corrections of order 25%.