Guang-lie Li | Searcharxiv

arXiv2002

Studying Kaon-pion S-wave scattering in K-matrix formalism

We generalize our previous work on ππscattering to Kπscattering, and re-analyze the experiment data of Kπscattering below 1.6 GeV. Without any free parameter, we explain KπI=3/2 S-wave phase shift very well by using t-channel rho and u-channel K^* meson exchange. With the t-channel and u-channel meson exchange fixed as the background term, we fit the KπI=1/2 S-wave data of the LASS experiment quite well by introducing one or two s-channel resonances. It is found that there is only one s-channel resonance between Kπthreshold and 1.6 GeV, i.e., K_0^*(1430) with a mass around 1438~1486 MeV and a width about 346 MeV, while the t-channel rho exchange gives a pole at (450-480i) MeV for the amplitude.

hep-ph↗

arXiv2000

A New Decomposition of pion-pion S-wave Interaction

The experimental isoscalar $ππ\toππ$ S-wave amplitude squared below 1.75 GeV is characterized by a very broad structure $f_0(400-1200)$ with two narrow dips due to its destructive interference with the $f_0(980)$ and $f_0(1500)$. The $f_0(1370)$ and $f_0(1710)$ do not show up clearly in the $ππ\toππ$ S-wave amplitude due to their weak coupling to $ππ$. This paper is about the controversial nature of the broad $f_0(400-1200)$. We decompose it into two parts, i.e., t-channel $ρ$ meson exchange plus an additional s-channel resonance $f_0(X)$. With the t-channel $ρ$ meson exchange fixed by the isotensor $ππ\toππ$ S-wave scattering, we re-fit the CERN-Munich (CM) data on $ππ$ scattering to get parameters for the $f_0(X)$. We find that the $f_0(X)$ is very broad with a nearby pole at (1.67-0.26i) GeV, while the t-channel $ρ$ meson exchange part produces a pole at (0.36-0.53i) GeV. The implication of our results for the study of $σ$ and glueball is discussed.

hep-ph↗