相关论文: pi-pi scattering: theory is ahead of experiment
We have analyzed pion-nucleon scattering using the manifestly relativistic covariant framework of Infrared Regularization up to {\cal O}(q^3) in the chiral expansion, where q is a generic small momentum. We describe the low-energy phase…
We show that a suitable setting for comparison of the low-energy representation for pion-pion scattering amplitudes, with dispersive representation for these amplitudes, is provided by certain manifestly crossing symmetric dispersion…
Present status of the study of the low energy $\pi\pi$ interaction is reviewed, including the recent results on reactions $\pi N \to\pi\pi N$ near threshold. Current experimental values of s-wave $\pi\pi$ scattering lengths are compared…
We review our analysis of $\pi K$ scattering using forward dispersion relations. The method yields a set of simple parameterizations that are compatible with forward dispersion relations up to 1.6 GeV while still describing the data. Once…
We study the properties of the Resonance-Spectrum Expansion near threshold in I=0 S-wave pion-pion scattering. The real part of the amplitude, when extrapolated from above threshold to below threshold, is found to vanish at a positive…
We review our recent analysis of pion-pion scattering data in terms of Roy equations and Forward Dispersion Relations, and present some preliminary results in terms of a new set of once-subtracted coupled equations for partial waves. The…
Following the Gauge Theory Bootstrap method proposed in our previous work [arXiv:2309.12402], we compute pion scattering phase shifts for all partial waves with angular momentum $\ell\le 3$ up to 2 GeV and calculate the low energy $\chi$PT…
The multichannel S- and P-wave amplitudes for the pion-pion scattering, constructed requiring analyticity and unitarity of the S-matrix and using the uniformization procedure, are elaborated using the dispersion relations with imposed…
We present a determination of the isospin-1/2 elastic $\pi K$ scattering amplitudes in S and P partial waves using lattice Quantum Chromodynamics. The amplitudes, constrained for a large number of real-valued energy points, are obtained as…
The S-wave scattering length of the strong pion-deuteron (pi D) scattering is calculated in the relativistic field theory model of the deuteron suggested in [1,2].The theoretical result agrees well with the experimental data. The important…
In a recent paper, Pelaez and Yndurain evaluate some of the low energy observables of pi pi scattering and obtain flat disagreement with our earlier results. The authors work with unsubtracted dispersion relations, so that their results are…
Starting from hyperbolic dispersion relations, we derive a closed system of Roy-Steiner equations for pion-nucleon scattering that respects analyticity, unitarity, and crossing symmetry. We work out analytically all kernel functions and…
Motivated by the $1/N_c$ expansion, we study a simple model in which the pi-K scattering amplitude is the sum of a current-algebra contact term and resonance pole exchanges. This phenomenological model is crossing symmetric and, when a…
Precise measurement of the $\pi\pi$-phase shift $\delta^0_0(E)$ at very low energies would provide, for the first time, the experimental evidence in favour of or against the existence of a large quark condensate in the QCD vacuum, which is…
We present a determination of the mass, width and coupling of the strange resonances appearing in pion-kaon scattering below 1.8 GeV, namely the much debated $K^*_0(800)$ or $\kappa$, the scalar $K^*_0(1430)$, the $K^*(892)$ and $K^*(1410)$…
Excited hadrons are seen as resonances in the scattering of lighter stable hadrons like $\pi$, $K$ and $\eta$. Many decay into multiple final states necessitating coupled-channel analyses. Recently it has become possible to obtain…
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…
We report about the recent results for s- and p-wave pion production in NN -> NNpi within effective field theory and discuss how the charge symmetry breaking in pn -> d pi^0 can be used to extract the strong contribution to the…
We establish the framework for the comparison of $\pi K$ scattering amplitudes from SU(3) chiral perturbation theory with suitable dispersive representations which result from the combination of certain fixed-t dispersion relations with…
The Roy equations determine the S- and P-wave pion-pion phase shifts on a low energy interval. They allow the derivation of threshold parameters from experimental data. We examine the solutions of these equations that are in the…