Related papers: Phase-shift analysis of low-energy pi+ p data
We develop a relativistic covariant and unitary description of the pion-nucleon interaction in a hadron-exchange model. The model is based on the solution of a dimensionally reduced (quasipotential) Bethe-Salpeter equation for the…
We show that the large corrections due to final state interactions (FSI) in the D^+\to \pi^-\pi^+\pi^+, D^+_s\to \pi^-\pi^+\pi^+, and D^+\to K^-\pi^+\pi^+ decays can be accounted for by invoking scattering amplitudes in agreement with those…
We use 2HEX smeared gauge configurations generated with an $\mathrm{N}_\mathrm{f}\mathrm{=2+1}$ clover improved Wilson action to investigate $\pi\pi$ scattering in the $\rho$ channel. The range of lattice spacings (0.054 to 0.12 fm) and…
The $\psi'\to J/\psi\pi^+\pi^-$ decay process provides a new way to extract the $\pi\pi$ $S$ wave phase shifts up to $0.59GeV$. In this paper we derive the formulae for extracting the $\pi\pi$ $S$ wave phase shifts from the invariant mass…
We improve our description of pion-pion scattering data by imposing additional requirements to our previous fits, in the form of once-subtracted Roy-like equations, while extending our analysis up to 1100 MeV. We provide simple and ready to…
Electromagnetic effects in the leptonic decay rates $\pi^+ \to \mu^+ \nu$ and $K^+ \to \mu^+ \nu$ are evaluated for the first time on the lattice. Following a method recently proposed in Ref. [1] the emission of virtual photons at leading…
We analyze the recent total cross section data for $pp \to p\Lambda K^+$ near threshold measured at COSY. Using an effective range approximation for the on-shell $p\Lambda$ S-wave final state interaction we extract from these data the…
The pi N --> eta N and eta N --> eta N partial wave T-matrices for the eight lowest partial waves have been obtained in a three coupled channel model with unitarity manifestly imposed. The two physical channels are pi_N and eta_N, and the…
A partial wave analysis of the centrally produced pi+pi- channel has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found. Evidence is found for the f0(980), f0(1300),…
A comprehensive analysis of $\pi K\rightarrow \pi K$ and $\pi\pi\rightarrow K\bar K$ amplitudes at large unphysical pion mass for all important partial waves is presented. A set of crossing-symmetric partial-wave hyperbolic dispersion…
We analyze the new threshold data for neutral pion photoproduction off protons in the framework of heavy baryon chiral perturbation theory. We show that large loop corrections are needed to understand the S--wave multipole $E_{0+}$ and that…
We perform a simultaneous analysis of s- and p-waves of the $S=-1$ meson-baryon scattering amplitude using all low-energy experimental data. For the first time, differential cross section data are included for chiral unitary coupled-channel…
Recent JLab data of the differential cross section for the reaction p(e,e'p)pi0 in the invariant mass region of 1.1 < W < 1.4 GeV at four-momentum transfer squared Q^2= 2.8 and 4.0 (GeV/c)$^2$ are analyzed with two models, both of which…
A sophisticated coupled-channel analysis is presented that combines different processes: the channels $\pi^0\pi^0\eta$, $\pi^0\eta\eta$ and $K^+K^-\pi^0$ from $\bar{p}p$ annihilations, the P- and D-wave amplitudes of the $\pi\eta$ and…
We extend the quark Born diagram formalism for hadron-hadron scattering to processes with valence $q\bar q$ annihilation, specifically $I=0$ and $I=1$ $\pi\pi$ and $I=1/2$ $K\pi$ elastic scattering. This involves the $s$-channel hybrid…
We carry out the semi--model analysis of existing data on the angular distributions of the $\gamma\gamma\rightarrow\pi^+ \pi^- ,\ \pi^0 \pi^0$ reactions with purpose to obtain S-wave cross section and D-wave's parameters. In the first time…
Experimental values of the lifetime of the 1s level of pionium and of the difference between the energies of the 2s and 2p levels yield values of the a(0c) and a(cc) elements of the s-wave scattering matrix for the 2-channel (pi+ pi-, pi0…
In this work, the two-photon-exchange (TPE) effects in $ep\rightarrow en\pi^+$ at small $-t$ are discussed within a hadronic model. Under the pion dominance approximation the TPE contribution to the amplitude can be described by a scalar…
The measurement of the pion-nucleon scattering lengths constitutes a high-precision test of the methods of Chiral Pertubation Theory, which is the low-energy approach of QCD. The pion-nucleon s-wave scattering lengths are related to the…
We present measurements of decay matrix elements for hadronic transitions of the form Upsilon(nS) -> pi pi Upsilon(mS) where (n, m) = (3, 1), (2, 1), and (3, 2). We reconstruct charged and neutral pion modes with the final state Upsilon…