Spin density matrix of the ω in the reaction p¯p→ωπ0

The spin density matrix of the ω has been determined for the reaction p¯p→ωπ0 with unpolarized in-flight data measured by the Crystal Barrel LEAR experiment at CERN. The two main decay modes of the ω into π0γ and π+π-π0 have been separately analyzed for various p¯ momenta between 600 and 1940 MeV/c. The results obtained with the usual method by extracting the matrix elements via the ω decay angular distributions and with the more sophisticated method via a full partial wave analysis are in good agreement. A strong spin alignment of the ω is clearly visible in this energy regime and all individual spin density matrix elements exhibit an oscillatory dependence on the production angle. In addition, the largest contributing orbital angular momentum of the p¯p system has been identified for the different beam momenta. It increases from Lp¯pmax = 2 at 600 MeV/c to Lp¯pmax = 5 at 1940 MeV/c

Technical Design Report for PANDA Electromagnetic Calorimeter (EMC)

This document presents the technical layout and the envisaged performance of the Electromagnetic Calorimeter (EMC) for the PANDA target spectrometer. The EMC has been designed to meet the physics goals of the PANDA experiment, which is being developed for the Facility for Antiproton and Ion Research (FAIR) at Darmstadt, Germany. The performance figures are based on extensive prototype tests and radiation hardness studies. The document shows that the EMC is ready for construction up to the front-end electronics interface

Observation of Electromagnetic Dalitz decays J/ψ\to P e^+e^-

Based on a sample of (225.3\pm2.8)\times 10^{6} J/\psi events collected with the BESIII detector, the electromagnetic Dalitz decays of J/\psi \to P e^+e^-(P=\eta'/\eta/\pi^0) are studied. By reconstructing the pseudoscalar mesons in various decay modes, the decays J/\psi \to \eta' e^+e^-, J/\psi \to \eta e^+e^- and J/\psi \to \pi^0 e^+e^- are observed for the first time. The branching fractions are determined to be \mathcal{B}(J/\psi\to \eta' e^+e^-) = (5.81\pm0.16\pm0.31)\times10^{-5}, \mathcal{B}(J/\psi\to \eta e^+e^-) = (1.16\pm0.07\pm0.06)\times10^{-5}, and \mathcal{B}(J/\psi\to \pi^0 e^+e^-)=(7.56\pm1.32\pm0.50)\times10^{-7}, where the first errors are statistical and the second ones systematic

γ

For detection of neutral particles and for electron identification in the target spectrometer region, PANDA will use an electromagnetic calorimeter consisting of about 16000 lead tungstate crystals. In combination with the shashlyk type calorimeter in the forward spectrometer, which is optimized to detect high energy photons at small polar angles, PANDA can cover nearly the full solid angle, which is important for the exclusive reconstruction of channels with many photons in the final state. Due to the short radiation length and small Moliere radius of lead tungstate, good spatial resolution can be achieved with a compact detector design. Especially for the forward endcap, good spatial resolution is needed for reconstruction of high energetic π 0 with good mass resolution. Figure 1 shows the expected π 0 mass resolution as a function of the π 0 momentum for several opening angle resolutions σα. α is defined as the angle between the photons from π 0 decay. From Monte Carlo simulation studies σα = 0.1 ◦ can be achieved for 5 GeV π 0 reconstructed with the forward endcap, which results in a π 0 mass resolution of about 4 MeV

Physics Performance Report for PANDA: Strong Interaction Studies with Antiprotons

To study fundamental questions of hadron and nuclear physics in interactions of antiprotons with nucleons and nuclei, the universal PANDA detector will be built. Gluonic excitations, the physics of strange and charm quarks and nucleon structure studies will be performed with unprecedented accuracy thereby allowing high-precision tests of the strong interaction. The proposed PANDA detector is a state-of-the art internal target detector at the HESR at FAIR allowing the detection and identification of neutral and charged particles generated within the relevant angular and energy range. This report presents a summary of the physics accessible at PANDA and what performance can be expected

"Table 3" of "Study of the reaction γp→pπ0η\gamma p\to p\pi^0\eta"

Differential cross sections as a function of the angles of the individual final state particles for the W range 1.9 to 2.1 GeV.. Errors shown are statistical only

"Table 5" of "Study of the reaction γp→pπ0η\gamma p\to p\pi^0\eta"

Differential cross sections as a function of the angles of combinations of final state particles for the W range 1.7 to 1.9 GeV.. Errors shown are statistical only

"Table 7" of "Photoproduction of pi0 omega off protons for E(gamma) < 3-GeV."

Differential cross section as a function of T-TMIN, the squared four momentum transfer to the P PI0 system

"Table 12" of "Photoproduction of pi0 omega off protons for E(gamma) < 3-GeV."

Differential cross section as a function of T-TMIN, the squared four momentum transfer to the P PI0 system

"Table 6" of "Study of the reaction γp→pπ0η\gamma p\to p\pi^0\eta"

Differential cross sections as a function of the angles of combinations of final state particles for the W range 1.9 to 2.1 GeV.. Errors shown are statistical only