An overview is given of Chiral Perturbation Theory and various applications to eta decays. In particular, the main decay η → 3π is discussed at the one-loop level, and estimates of the higher order corrections are given. The importance of p6 and higher order effects in double Dalitz and η → π0γγ decays is pointed out. In all these cases the need for new experimental results is stressed.

Objective: To investigate if muscle strength and muscle activation patterns are associated with increased knee abduction during two functional tasks, commonly used in rehabilitation for individuals with anterior cruciate ligament reconstruction (ACLR). Design: Cross-sectional study. Setting: Laboratory. Participants: 24 women and 29 men approximately 7 months after ACLR. Main outcome measures: Iso

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.

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

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

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.

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

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

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

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.

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.

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

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.

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

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

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

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

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.