arXiv subjects

Saša Ceci

Publications and source records attributed to Saša Ceci.

3 recordsLinked to original sources

arXiv2025

Resolving the $Δ(1232)$ partial width anomaly: Complex pole residue is not a fundamental resonance property

The resonant properties of excited hadrons are commonly identified with the complex pole positions and residues of the scattering amplitude. The mass and total decay width are given by position, whereas the partial width is given by the magnitude of the residue. If this identification was correct, the partial width of famous $Δ(1232)$ would be larger than its total width. By using a simple model that predicts residue phases of prominent baryons $N^*$, $Δ$, $Λ$, $Σ$, and low mass mesons, we resolve this anomaly and show that the residue cannot be a fundamental resonant property.

hep-ph↗

arXiv2020

The strangest non-strange meson is not so strange after all

The broad non-strange meson $f_0$(500) is considered to be a non-Breit-Wigner resonance. It is generally assumed that if a resonance is broad it can hardly be described by a Breit-Wigner form. We show here that is not true neither for the broad Z boson, nor for the much narrower $Δ(1232)$, and explain why the $f_0$(500) fits with them perfectly. Key differences between them boil down to a single parameter: the angle at which we see the resonance pole from the threshold, which explains the background, the residue phase, and the difference between the pole and Breit-Wigner parameters.

hep-ph↗

arXiv2017

Physical properties of resonances as the building blocks of multichannel scattering amplitudes

We propose a simple formula for multichannel resonant scattering with parameters related to physical resonant properties. It can be used to predict residue phase from other resonant parameters and describe the shape of scattering amplitudes close to the resonance without any background contributions or fitting. It works well even for overlapping resonances. Imposing unitarity to the proposed formula enabled us to explain some puzzling features of much more advanced models.

hep-ph↗