Related papers: First estimates of the $(\alpha + \beta)^{\pi}$ fr…
A new analysis of S-wave production amplitudes for the reaction $\pi^- p_{\uparrow} \rightarrow \pi^+ \pi^- n$ on a transversely polarized target is performed. It is based on the results obtained by the CERN-Cracow -Munich collaboration in…
A measurement of the double-polarization observable $E$ for the reaction $\gamma p\to \pi^0 p$ is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C$_4$H$_9$OH)…
The double-polarization observable $E$ was studied for the reaction $\gamma p\to p\omega$ using the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B at the Thomas Jefferson National Accelerator Facility and the longitudinally-polarized…
We calculate the electromagnetic corrections needed to obtain isospin invariant hadronic pion-pion s-wave scattering lengths a^0, a^2 from the elements a_cc, a_0c of the s-wave scattering matrix for the (\pi^+ \pi^-, \pi^0 \pi^0) system at…
We calculate the decay of pionium atoms into two photons. The pion polarizability gives rise to a 10% correction to the corresponding decay width for pointlike pions. This opens the possibility to obtain the difference between the electric…
Amplitudes for the reaction $\pi^-p\to \Lambda K^0$ are reconstructed from data on the differential cross section $d\sigma/d\Omega$, the recoil polarization $P$, and on the spin rotation parameter $\beta$. At low energies, no data on…
Recent data from the PIONS$@$MAX-lab Collaboration, measuring the total cross section of the pion incoherent photoproduction $\gamma d\to\pi^-pp$ near threshold, have been used to extract the E$_{0+}$ multipole and total cross section of…
We study decay distributions in B -> K pi pi gamma, combining contributions from several overlapping resonances in a K pi pi mass range near 1400 MeV, (1^+) K_1(1400), (2^+) K^*_2(1430) and (1^-) K^*(1410). A method is proposed for using…
Recently the radiative B decay to the strange axial-vector mesons, B --> K1(1270) gamma, has been observed with rather large branching ratio. This process is particularly interesting as the subsequent K1 decay into its three body final…
We reconsider Muskhelishvili-Omn\`es (MO) dispersive representations of photon-photon scattering to two pions, motivated by the very high statistics results recently released by the Belle collaboration for charged as well as neutral pion…
The Compton double-polarization observable $\Sigma_{2z}$ has been measured for the first time in the $\Delta(1232)$ resonance region using a circularly polarized photon beam incident on a longitudinally polarized target at the Mainz…
We perform an Amplitude Analysis of the world published data on $\gamma\gamma\to\pi^+\pi^-$ and $\pi^0\pi^0$. These are dominated in statistics by the recently published results from Belle on the charged pion channel. Nevertheless, having…
We report a measurement of the spin-dependent total cross section ratios delta_sigma_T/sigma_tot and delta_sigma_L/sigma_tot of the pp --> pp pi^0 reaction between 325 MeV and 400 MeV. The experiment was carried out with a polarized…
A precise measurement of the differential cross-sections $d\sigma/d\Omega$ and the linearly polarized photon beam asymmetry $\Sigma_3$ for Compton scattering on the proton below pion threshold has been performed with a tagged photon beam…
A first measurement of longitudinal as well as transverse spin correlation coefficients for the reaction $\vec{p}\vec{p}\to pn\pi^+$ was made using a polarized proton target and a polarized proton beam. We report kinematically complete…
We propose a model for $D^+ \to \pi^+ \pi^- \pi^+$ decays following experimental results which indicate that the two-pion interaction in the $S$-wave is dominated by the scalar resonances $f_0(600)/\sigma$ and $f_0(980)$. The weak decay…
The reaction $\gamma \, p \rightarrow K^0_S\,\Sigma^+$ is studied in the photon energy range from threshold. Linearly polarised photon beams from coherent bremsstrahlung enabled the first measurement of photon beam asymmetries in this…
A model for high-energy, small-angle pion-nucleus bremsstrahlung, $ \pi^- +A\to\pi^- +\gamma +A$,is developed within the Glauber diffraction theory. Special attention is focussed on the possibility of measuring the pion polarisability in…
Generalized nucleon polarizabilities for virtual photons can be defined in terms of electroproduction cross sections as function of the 4-momentum transfer $Q^2$. In particular, the sum of the generalized electric and magnetic…
The final state interactions in $K^\pm\to\pi^\pm\pi^0\pi^0$ decays are considered using the methods of non-relativistic quantum mechanics. We show how to take into account the largest electromagnetic effects in the analysis of experimental…