相关论文: Further Analysis on \sigma-particle Properties
Motivated by the presence of nearby thresholds in other baryon-meson channels with I=1 and S=-1, we investigate whether the Lambda pi scattering phase shifts at a center-of-mass energy equal to the Xi mass could be larger than suggested by…
The phase variation of the sigma -> pi-pi amplitude is accurately determined as a function of mass from BES II data for J/Psi -> omega-pi-pi. The determination arises from interference with the strong b1(1235)-pi amplitude. The observed…
We calculate the S and P wave phase shifts in $\Lambda - \pi$ scattering at the $\Xi$ mass using the full relativistic $SU(3)_L \times SU(3)_R$ chiral perturbation theory. We get small phase shifts similar to previous calculations using $…
In this talk I summarize a recently proposed mechanism to understand pi pi scattering to 1 GeV. The model is motivated by the 1/Nc expansion to QCD, and includes a current algebra contact term and resonant pole exchanges. Chiral symmetry…
A set of well known once subtracted dispersion relations with imposed crossing symmetry condition is used to modify unitary multichannel $S$ ($\pi\pi$, $K \bar K$, and $\eta\eta$) and $P$ ($\pi\pi$, $\rho 2\pi$, and $\rho\sigma$) wave…
We have performed a new model independent amplitude analysis of reaction $\pi^- p \to \pi^- \pi^+ n$ measured at CERN at 17.2 GeV/c on polarized target. The analysis extends the range of dipion mass from 600--880 MeV used in the previous…
We set up a general framework to describe $\pi\pi$ scattering below 1 GeV based on chiral low-energy expansion with possible spin-0 and 1 resonances. Partial wave amplitudes are obtained with the $N/D$ method, which satisfy unitarity,…
The \sigma(600) and \kappa(900), observed in the phase shift analyses, satisfy rather well the mass and width relation predicted by the SU(3)LsM and the SU(3)LsM with the vector and axial-vector meson nonets, and deserve to be the members…
This work is a direct and model-independent measurement of the low mass $\pi^+\pi^-$ phase motion in the $D^+ \to \pi^-\pi^+\pi^+$ decay. The results show a strong phase variation, compatible with an isoscalar $\sigma(500)$ meson. This…
We study the strong interaction S-wave \Lambda\pi phase shift in the region of the \Xi mass in the framework of a relativistic chiral unitary approach based on coupled channels. All parameters have been previously determined in a fit to…
In the paper Phys. Rev. {\bf D83}, 054008 (2011) we constructed the $\pi\pi$ scattering amplitude $T^0_0$ with regular analytical properties in the $s$ complex plane, describing both experimental data and the results based on chiral…
A S-wave \pi\pi resonance below 1 GeV/c^2, sigma has been observed in analyses of the phase shift data of \pi\pi scatterings. It is important to observe it in production processes. A huge events of \pi^0\pi^0 below 1 GeV/c^2 is seen in the…
The scalar-isoscalar, scalar-isotensor and vector-isovector pi-pi amplitudes have been fitted simultaneously to experimental data and to to Roy's equations. Resulting pi-pi phase shifts up to 1600 MeV and near threshold observables have…
The $\pi\pi$ scattering amplitude in the $\sigma$-channel is studied at finite baryonic density in the framework of a chiral unitary approach which successfully reproduces the meson meson phase shifts and generates the $f_0$ and $\sigma$…
Threshold expansions of the $\pi\pi$ and $K\overline{K}$ spin 0 and isospin 0 scattering amplitudes are performed. Scattering lengths, effective ranges and so--called volume parameters are evaluated. Good agreement with the existing…
BES data on $J/\psi \to \gamma (K^{\pm} K_S^0 \pi^{\mp})$ are presented. There is a strong peak due to $\eta(1440)/\iota$, which is fitted with a Breit-Wigner amplitude with $s$-dependent widths for decays to $K^*K$, $\kappa K$, $\eta…
We extend our study of the $K\pi$ system to moving frames and present an exploratory extraction of the masses and widths for the $K^*$ resonances by simulating $K\pi$ scattering in p-wave with $I=1/2$ on the lattice. Using $K\pi$ systems…
The $\pi\pi$ scattering amplitude with regular analytical properties in the $s$ complex plane has been constructed. It describes simultaneously the data on the $\pi\pi$ scattering, $\phi\to\pi^0\pi^0\gamma$ decay and $\pi\pi\to K\bar K$…
We use a twice-subtracted partial-wave dispersion relation in the elastic unitarity approximation for final-state interactions to study the amplitude for the delta I = 1/2 CP-conserving weak process K+spurion->pi+pi. We use a simple…
From recent analysis of the $\pi\pi$ scattering amplitude, it has been claimed that there exists a broad and light $\sigma$ meson. However, if this meson really exists, it must also appear in other observables such as the pion scalar form…