494 citations · 1.7k across the 10 of their papers we have counts for
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Solutions of Roy equations for variable pion mass
Gilberto Colangelo
The Roy equations for the and waves are solved for pion masses below the physical value in the region between threshold and $s_A=0.84\GeV^2$. The analysis is based on the a…
Mass and width of the lowest resonance in QCD
Irinel Caprini, Gilberto Colangelo, Heinrich Leutwyler
We demonstrate that near the threshold, the pi pi scattering amplitude contains a pole with the quantum numbers of the vacuum - commonly referred to as the sigma - and determine it…
On the precision of the theoretical predictions for pi pi scattering
I. Caprini, G. Colangelo, J. Gasser +1
In a recent paper, Pelaez and Yndurain evaluate some of the low energy observables of pi pi scattering and obtain flat disagreement with our earlier results. The authors work with…
The quark condensate from K_{e_4} decays
G. Colangelo, J. Gasser, H. Leutwyler
We show that, independently of the size of the quark condensate, chiral symmetry correlates the two S-wave ππscattering lengths. In view of this constraint, the new precision data…
The pi pi S-wave scattering lengths
G. Colangelo, J. Gasser, H. Leutwyler
We match the known chiral perturbation theory representation of the pi pi scattering amplitude to two loops with a phenomenological description that relies on the Roy equations. On…
Roy equation analysis of pi pi scattering
B. Ananthanarayan, G. Colangelo, J. Gasser +1
We analyze the Roy equations for the lowest partial waves of elastic pi pi scattering and demonstrate that the two S-wave scattering lengths a_0^0 and a_0^2 are the essential param…
Supersymmetric contributions to direct CP violation in K -> pi pi gamma decays
G. Colangelo, G. Isidori, J. Portoles
We analyze the supersymmetric contributions to direct-CP-violating observables in decays induced by gluino-mediated magnetic-penguin operators. We find that $\epsp_{+-γ…
Double Chiral Logs
J. Bijnens, G. Colangelo, G. Ecker
We determine the full structure of the leading (double-pole) divergences of O(p^6) in the meson sector of chiral perturbation theory. The field theoretic basis for this calculation…
The Vector and Scalar Form Factors of the Pion to Two Loops
J. Bijnens, G. Colangelo, P. Talavera
We calculate the vector and scalar form factors of the pion to two loops in Chiral Perturbation Theory. We estimate the unknown O(p^6) constants using resonance exchange. We make a…
Tau Decays and Chiral Perturbation Theory
G. Colangelo, M. Finkemeier, R. Urech
In a small window of phase space, chiral perturbation theory can be used to make standard model predictions for tau decays into two and three pions. For , we give the a…
Elastic scattering to two loops
J. Bijnens, G. Colangelo, G. Ecker +2
We evaluate analytically the elastic scattering amplitude to two loops in chiral perturbation theory and give numerical values for the two --wave scattering lengths and for…