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abstract: 'We review the status of the coupling constants of chiral Lagrangians in the meson sector, the so-called low-energy constants (LECs). Special emphasis is put on the chiral $SU(2)$ and $SU(3)$ Lagrangians for the strong interactions of light mesons. The theoretical and experimental input for determining the corresponding LECs is discussed. In the two-flavour sector, we review the knowledge of the $O(p^4)$ LECs from both continuum fits and lattice QCD analyses. For chiral $SU(3)$, NNLO effects play a much bigger role. Our main new results are fits of the LECs $L_i$ both at NLO and NNLO, making extensive use of the available knowledge of NNLO LECs. We compare our results with available lattice determinations. Resonance saturation of LECs and the convergence of chiral $SU(3)$ to NNLO are discussed. We also review the status of predictions for the LECs of chiral Lagrangians with dynamical photons and leptons.'
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LU TP 14-16\
UWThPh-2014-10\

[**Mesonic low-energy constants**]{}\
[**Johan Bijnens$^{1}$ and Gerhard Ecker$^{2}$**]{}\

${}^{1)}$ Department of Astronomy and Theoretical Physics, Lund University,\
Sölvegatan 14A, SE 223-62 Lund, Sweden\
${}^{2)}$ University of Vienna, Faculty of Physics,\
Boltzmanngasse 5, A-1090 Wien, Austria

INTRODUCTION
============

Low-energy meson physics and the study of the strong 