Related papers: $\Delta$ Contribution to $ pp \to pp\pi^0$
Model independent formulae are derived for the polarizations and spin correlations of protons in the final state of $pp \to pp\omega $, taking into consideration all the six threshold partial wave amplitudes $f_1, ..., f_6$ covering $Ss,…
We solve the dispersion relation for the P-wave pi pi amplitude.We discuss the role of the left hand cut vs Castillejo-Dalitz-Dyson (CDD), pole contribution and compare the solution with a generic quark model description. We review the the…
The large two-pion exchange amplitudes are calculated in HB$\chi$PT and their net contribution to the reaction cross section is large.
A model-independent irreducible tensor formalism which has been developed earlier to analyze measurements of $\vec{p}\vec{p}\to pp \pi^\circ$, is extended to present a theoretical discussion of $\vec{p}\vec{p}\to pp \omega$ and the…
The amplitudes for photoproduction of two pseudoscalars on a nucleon are expanded in the overall c.m. frame in a model independent way with respect to the contribution of the final state partial wave of total angular momentum $J$ and its…
Within fixed-t dispersion relations the results of new VPI partial-wave analysis for the multipole amplitudes $M_{1+}^{3/2},E_{1+}^{3/2}$ are successfuly described, and the resonance and nonresonance contributions into these amplitudes are…
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…
We have used a conventional model for the $pp \rightarrow pp \pi^{0}$ reaction consisting of the Born term plus the $s$-wave rescattering term. As a novelty we have introduced the off shell dependence of the $\pi N$ $s$-wave isoscalar…
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 $pp \to nK^+\Sigma^+$ reaction is a very good isospin 3/2 filter for studying $\Delta^{++*}$ decaying to $K^+\Sigma^+$. With an effective Lagrangian approach, contributions from a previous ignored sub-$K^+\Sigma^+$-threshold resonance…
In this report, we present our recent studies on the Lambda(1405,1/2-)=Lambda* photoproduction via the gamma p -> K+ pi Sigma scattering process, employing a coupled-channel formalism, i.e., the chiral unitary model, which respects chiral…
The total cross section for the pp -> pp pi^0 reaction at energies close to threshold is calculated using a covariant one-boson-exchange model, where a boson B created on one of the incoming protons is converted into a neutral pion on the…
A recent analysis of pion photo-production multipoles using p(g,pi0) data from Mainz is repeated, successively adding constraints from other observables and varying the number of fitted partial waves. The original analysis is shown to have…
We present a theoretical analysis of the $D^-\to \pi^+\pi^- \ell\bar\nu$ and $\bar D^0\to \pi^+\pi^0 \ell\bar\nu$ decays. We construct a general angular distribution which can include arbitrary partial waves of $\pi\pi$. Retaining the…
The amplitudes of the pion electroproduction from the nucleon are derived up to third order in the chiral effective theory including explicit $\Delta$(1232) >. The Q^2 evolutions of weighted integrals of amplitudes are presented.
The single-pion production reactions $pp\to d\pi^+$, $pp\to np\pi^+$ and $pp\to pp\pi^0$ were measured at a beam momentum of 0.95 GeV/c ($T_p \approx$ 400 MeV) using the short version of the COSY-TOF spectrometer. The implementation of a…
A model calculation for pion production in nucleon-nucleon collisions is presented. Direct production, pion rescattering and contributions from pair diagrams are taken into account. The amplitudes for the elementary processes are based on…
The gamma p ---> pi+ pi- p reaction, in combination with data from the pi N ---> pi pi N reaction, allows one to obtain the s- and d-wave amplitudes for the N*(1520) decay into Delta pi with absolute sign with respect to the N*(1520) ---> N…
This paper presents results from partial-wave analyses of the photoproduction reactions $\gamma p \rightarrow \eta p$ and $\gamma n \rightarrow \eta n$. World data for the observables \DSG, $\Sigma$, $T$, $P$, $F$, and $E$ were analyzed as…
The recoil proton polarization in the $\pi^0$ production off the proton with longitudinally polarized electron beam has been studied as a means to measure quadrupole components in the N to $\Delta$ transition. On top of the $\Delta$…