Sigma-Meson and Confinement Singularity

Abstract

We describe the meson-meson data for the ($I{J}^{PC}=00^{++}$) wave at $280\le \sqrt{s}\le 1900$ MeV in two approaches: (i) the K-matrix approach and (ii) the dispersion relation D-matrix method. With a good description of low energy data (at $280\le \sqrt{s}\le 900$ MeV) as well as the data of two-meson transition amplitudes and antiproton-proton annihilation into three pseudoscalar meson states (at $450\le \sqrt{s}\le 1950$ MeV) we have found the positions of the resonance poles: (i) for the $\sigma$ meson pole: $M_{\sigma }=(390\pm 35)-i(235\pm 50)$ MeV; (ii) two poles for the $f_0(980)$, on the second sheet (under the $\pi \pi$ cut): $M_I=(1011\pm 5)-i(35\pm 5)$ MeV, and on the third sheet (under the $\pi \pi$ and $K\bar{K}$ cuts), $M_{II}=(1035\pm 50)-i(460\pm 50)$ MeV; for the $f_0(1370)$ meson, $M=(1285\pm 30)-i(160\pm 20)$ MeV; for the $f_0(1500)$ meson, $M=(1488\pm 4)-i(53\pm 5)$ MeV; for the $f_0(1790)$ meson, $M=(1775\pm 25)-i(140\pm 15)$ MeV and for the broad state $f_0(1200-1600)$ $M=(1540\pm 120)-i(550\pm 70)$ MeV. Our estimation of the scalar-isoscalar scattering length obtained under different parameterizations and assumptions about the quality of low energy $\pi \pi$ scattering data is $a_0^0=(0.215\pm 0.040){\mu }_{\pi }^{-1}$. We also discuss the idea according to which the $\sigma$-meson could be a remnant of the confinement singularity, $1/s^2$, in a white channel.

23 pages

References in corpus (2)

• The pion-pion scattering amplitude. IV: Improved analysis with once subtracted Roy-like equations up to 1100 MeV
• The mass of the sigma pole