Model independent extraction of the pole and Breit-Wigner resonance parameters

Abstract

We show that a slightly modified Breit-Wigner formula can successfully describe the total cross section even for the broad resonances, from light rho(770) to the heavy Z boson. In addition to mass, width, and branching fraction, we include another resonance parameter that turns out to be directly related to the pole residue phase. The new formula has two mathematically equivalent forms: one with the pole, and the other with the Breit-Wigner parameters.

Final version with corrected typo in Eq. (14); 5 pages, 5 figures, 2 tables