RT Journal Article
T1 Precision of chiral-dispersive calculations of π π scattering
A1 Peláez Sagredo, José Ramón
A1 Ynduráin, F. J.
AB We calculate the combination 2a⁰_(0)-5a₀(^2) (the Olsson sum rule) and the scattering lengths and effective ranges a₁,a₂^(2) and b₁,b₂^(I) dispersively (with the Froissart-Gribov representation) using, at low energy, the phase shifts for π π scattering obtained by Colangelo, Gasser, and Leutwyler (CGL) from the Roy equations and chiral perturbation theory, plus experiment and Regge behavior at high energy, or directly, using the CGL parameters for a's and b's. We find mismatch, both among the CGL phases themselves and with the results obtained from the pion form factor. This reaches the level of several (2 to 5) standard deviations, and is essentially independent of the detai᾿ls of the intermediate energy region (0.82 ≤ E ≤ 1.42 GeV) and, in some cases, of the high energy behavior assumed. We discuss possible reasons for this mismatch, in particular in connection with an alternate set of phase shifts.
PB Amer Physical Soc
SN 0556-2821
YR 2003
FD 2003-10-01
LK https://hdl.handle.net/20.500.14352/51737
UL https://hdl.handle.net/20.500.14352/51737
LA eng
NO ©2003 The American Physical Society.One of us (F.J.Y.) is grateful to G. Colangelo, J. Gasser, and H. Leutwyler for very interesting discussions that triggered his interest in this subject. Both of us thank again Professor Leutwyler for a very useful critical reading of a preliminary draft, which, in particular, allowed us to correct a few inconsistencies. J.R.P. acknowledges support from the Spanish CICYT projects PB98-0782 and BFM2000 1326, as well as from the Marie Curie Fellowship, grant No. MCFI- 2001-01155.
NO Spanish CICYT
NO Marie Curie Fellowship
DS Docta Complutense
RD 17 abr 2025