Properties of the Lambda(1520) Resonance from High-Precision Electroproduction Data

TL;DR

This study precisely measures the mass and width of the Lambda(1520) resonance using high-resolution electroproduction data, highlighting the importance of background assumptions and providing the first pole position estimate.

Contribution

It offers new high-precision measurements of the Lambda(1520) resonance's parameters and introduces the first estimation of its pole position, improving understanding of its properties.

Findings

Mass = 1520.4 ± 0.6 (stat) ± 1.5 (syst) MeV

Width = 18.6 ± 1.9 (stat) ± 1 (syst) MeV

Pole position estimates are smaller than Breit-Wigner values

Abstract

High-resolution spectrometer measurements of the reaction H(e,e'K+)X at small Q2 are used to extract the mass and width of the Lambda(1520). We investigate the influence of various assumptions used in the extraction. The width appears to be more sensitive to the assumptions than the mass. To reach a width uncertainty about 1 MeV or better, one needs to know the structure of the non-resonant background. Based on the new Jefferson Lab Hall A data, our final values for the Breit-Wigner parameters are M = 1520.4 +- 0.6 (stat) +- 1.5 (syst) MeV, Gamma = 18.6 +- 1.9 (stat) +- 1 (syst) MeV. For the first time, we also estimate the pole position for this resonance and find that both the pole mass and width seem to be smaller than the Breit-Wigner values.