Assessment of systematic theory uncertainties in IAM unitarization
Abstract
Effective Field Theories (EFTs) for Goldstone Boson scattering at a low order allow the computation of nearthreshold observables in terms of a few coefficients arranged by a counting. As a matter of principle they should make sense up to an energy scale E ∼ 4πF but the expansion in powers of momentum violates exact elastic unitarity and renders the derivative expansion unreliable at much lower energies. If newphysics deviations from the Standard Model are found and encoded in lowenergy coefficients, perhaps at the LHC, it will be profitable to extend the reach of the EFT to regimes where partial waves are saturating unitarity. The methods known in hadron physics as "Unitarized Chiral Perturbation Theory" extend the EFT up to its nominal reach or up to the first new physics resonance or structure (if found below that energy reach) in the partial wave amplitude, but they usually have unknown uncertainties. We recapitulate our analysis of the systematic theory uncertainties of the well known Inverse Amplitude Method (IAM).
 Publication:

Nuclear and Particle Physics Proceedings
 Pub Date:
 July 2021
 DOI:
 10.1016/j.nuclphysbps.2021.05.022
 arXiv:
 arXiv:2012.02616
 Bibcode:
 2021NPPP..312...82E
 Keywords:

 Theoretical uncertainties;
 Unitarization;
 Effective Theory;
 Inverse Amplitude Medhod;
 High Energy Physics  Phenomenology
 EPrint:
 5 page letter for the proceedings of QCD20, 23TH International Conference in Quantum Chromodynamics (2720 October 2020, Montpellier)