M. Jacewicz

Double-pionic fusion of nuclear systems and the "ABC" effect: approaching a puzzle by exclusive and kinematically complete measurements.

The ABC effect-a puzzling low-mass enhancement in the pipi invariant mass spectrum, first observed by Abashian, Booth, and Crowe-is well known from inclusive measurements of two-pion production in nuclear fusion reactions. Here we report on the first exclusive and kinematically complete measurements of the most basic double-pionic fusion reaction pn-->dpi;{0}pi;{0} at beam energies of 1.03 and 1.35 GeV. The measurements, which have been carried out at CELSIUS-WASA, reveal the ABC effect to be a (pipi)_{I=L=0} channel phenomenon associated with both a resonancelike energy dependence in the integral cross section and the formation of a DeltaDelta system in the intermediate state. A corresponding simple s-channel resonance ansatz provides a surprisingly good description of the data.

The WASA Detector Facility at CELSIUS

The WASA 4 pi multidetector system, aimed at investigating light meson production in light ion collisions and eta meson rare decays at the CELSIUS storage ring in Uppsala is presented. A unique fea ...

Precision measurement of σ(e+e−→π+π−γ)/σ(e+e−→μ+μ−γ) and determination of the π+π− contribution to the muon anomaly with the KLOE detector

We have measured the ratio

Two-pion production in proton-proton collisions ― experimental total cross sections and their isospin decomposition

\sigma(e^+e^-\rightarrow\pi^+\pi^-\gamma)/\sigma(e^+e^-\rightarrow \mu^+\mu^-\gamma)

Measurement of eta meson decays into lepton-antilepton pairs

, with the KLOE detector at DA

Delta Delta excitation in proton-proton induced pi(0)pi(0) production

\Phi

Test of CPT and Lorentz symmetry in entangled neutral kaons with the KLOE experiment

NE for a total integrated luminosity of

Exclusive measurements of pd→He3ππ: The ABC effect revisited

\sim

Measurement of the eta -> 3 pi(0) slope parameter alpha with the KLOE detector

240 pb

Exclusive measurement of two-pion production in the dd -g He-4 pi pi reaction

^{-1}