Related papers: The mass of the sigma pole
Using 14M $\psi(2S)$ events accumulated by BESII at the BEPC, a Covariant Helicity Amplitude Analysis is performed for $\psi(2S)\to\pi^+\pi^-J/\psi, J/\psi\to \mu^+\mu^-$. The $\pi^+\pi^-$ mass spectrum, distinctly different from phase…
We investigate the determination of the $\sigma$ pole from $\pi\pi$ scattering data below the $K\bar{K}$ threshold, including the new precise results obtained from $K_{e4}$ decay by NA48/2 Collaboration. We discuss also the experimental…
Using a sample of 58 million $J/\psi$ events recorded in the BESII detector, the decay $J/\psi \to \omega \pi^+ \pi^-$ is studied. There are conspicuous $\omega f_2(1270)$ and $b_1(1235)\pi$ signals. At low $\pi \pi$ mass, a large broad…
Partial wave analyses have been performed on BES data to study scalar mesons. There is evidence for the $\kappa$ near the $K\pi$ threshold and the pole position is $(760\sim840) -$i$(310\sim 420)$ MeV. The $\sigma$ peak is seen in…
New Focus data on Dplus -> Kminus piplus piminus are fitted to the kappa, together with earlier data from LASS, E791 and BES 2. There is a clear low mass K-pi peak due to the kappa pole. Inclusion of the I=3/2 K-pi amplitude gives only a…
We show how the new precise data on kaon decays together with forward dispersion relations, sum rules and once- and twice-subtracted Roy's equations allow for a precise determination of the sigma meson pole position. We present a comparison…
Resonance pole positions of the $f_0(500)$ alias $\sigma(500)$ meson are computed and plotted as a continuous function of pion mass in the framework of a unitary and analytic coupled-channel model for scalar mesons as dynamical $q\bar{q}$…
Based on a sample of 7.8 million BESI $J/\psi$ events, the decay of $ J/\psi \to \omega \pi^+ \pi^-$ is studied. A low mass enhancement in the $\pi^+ \pi^-$ invariant mass spectrum recoiling against $\omega$ particle is clearly seen which…
We investigate the determination of the pole associated to $\sigma$ from $\pi\pi$ scattering data below the $K\bar{K}$ threshold, including the new precise data from $K_{e4}$ decay reported recently by the NA48/2 Collaboration. Using a…
The hypothesis of sigma meson pole dominance in the Delta I = 1/2 K -> pi pi amplitudes is tested by using the K_L-K_S mass difference.
We study two coupling constants reported as predictions of the sigma model. We obtain an spectral distribution, in terms of the \sigma meson regularized self- energy in one loop order, which is consistently with the Breit-Wigner…
We review how the use of recent precise data on kaon decays together with forward dispersion relations (FDR) and Roy's equations allow us to determine the sigma resonance pole position very precisely, by using only experimental input. In…
BES II data for J/Psi->K*(890)Kpi reveal a strong kappa peak in the Kpi S-wave near threshold. Both magnitude and phase are determined in slices of Kpi mass by interferences with strong Ko(1430), K1(1270) and K1(1400) signals. The phase…
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…
Both sigma and kappa are well established from E791 data on D->3pi and Ds->Kpipi and BES II data on J/Psi -> omega pi pi and KKpipi. These fits are accurately consistent with pipi and Kpi elastic scattering when one allows for the Adler…
We review how the use of recent precise data on kaon decays together with forward dispersion relations (FDR) and Roy's equations allow us to determine the sigma resonance pole position very precisely, by using only experimental input. In…
A combined fit is made to E791 data on D->K-pi-pi, LASS data on K-pi elastic scattering, and BES II data on J/Psi->K*(890)-K-pi.In all cases, the K-pi S-wave is fitted well with a kappa resonance and Ko(1430); the kappa requires an…
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…
A pole in the D-pi S-wave analogous to the sigma and kappa is predicted at 2098 +- 40 - i(260 +- 40) MeV. The main objective of this paper is to provide formulae for fitting it to data.
We use the available data on e+ e- -> hadrons to determine the value of the QED coupling at the Z pole. The inclusion of recent preliminary BES-II data in the analysis is found to reduce the ambiguity in the determination of the coupling,…