相关论文: Khuri-Treiman equations for $\pi\pi$ scattering
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…
The scattering of $\gamma \pi \to \pi \pi$ is studied using the axial anomaly, elastic unitarity, analyticity and crossing symmetry. Using the technique to derive the Roy's equation, an integral equation for the P-wave amplitude is obtained…
Starting from hyperbolic dispersion relations, we derive a system of Roy--Steiner equations for pion Compton scattering that respects analyticity, unitarity, gauge invariance, and crossing symmetry. It thus maintains all symmetries of the…
We describe a rearrangement of the standard expansion of the symmetry breaking part of the QCD effective Lagrangian that includes into each order additional terms which in the standard chiral perturbation theory ($\chi$PT) are relegated to…
We study dispersive representations of nonlocal form factors in $K^+ \to \pi^+ \ell^+ \ell^-$ and $K^+ \to \pi^+ \nu \bar{\nu}$ decays, with an aim of improving the theoretical description of the spectrum and decay rate of the neutrino…
Compound resonances in nucleon-nucleus scattering are related to the discrete spectrum of the target. Such resonances can be studied in a unified and general framework by a scattering model that uses sturmian expansions of postulated…
We summarize the application of dispersion relations for the determination of low energy $\pi K$ interactions. In particular, we present our recent dispersive analyses for the complete study of both $\pi K\to \pi K$ and $\pi \pi \rightarrow…
We study the decay $J/\psi\to\pi^{+}\pi^{-}\pi^{0}$ within the framework of the Khuri-Treiman equations. We find that the BESIII experimental di-pion mass distribution in the $\rho(770)$-region is well reproduced with a once-subtracted…
Coupled-channel dynamics for scattering and production processes in partial-wave amplitudes is discussed from a perspective that emphasizes unitarity and analyticity. We elaborate on several methods that have driven to important results in…
The theoretical predictions for the subtraction constants lead to a very accurate dispersive representation of the pi pi scattering amplitude below 0.8 GeV. The extension of this representation up to the maximum energy of validity of the…
A unitary framework based on the Bakamjian-Thomas construction of relativistic quantum mechanics is used to describe two-pion scattering from threshold to 1400 MeV. The framework properly includes unitarity cuts for one-, two- and…
In the context of chiral SU(2) perturbation theory, pion-kaon scattering is analysed near the threshold to fourth chiral order. The scattering amplitude is calculated both in the relativistic framework and by using an approach similar to…
Low energy theorems are derived for the coefficients of the effective range expansion in s-wave nucleon-nucleon scattering valid to leading order in an expansion in which both $m_\pi$ and $1/a$ (where $a$ is the scattering length) are…
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…
In this talk we discuss the relevance of dispersive methods and their different applications to obtain simple but rigorous parameterizations of pion-pion and kaon-pion scattering. We show as an example our latest dispersive analysis of $\pi…
Medium and high energy absorptive parts contribute to dispersive expressions for D- wave scattering lengths, $a^0_2$ and $a^2_2$. For the model employed by Basdevant, Frogatt and Peterson we find the D- wave driving term contributions to…
We carry out an analysis of $\pi\pi$ scattering in the $IJ=00$, $11$ and $20$ channels in configuration space up to a maximal center-of-mass energy $\sqrt{s}=1.4$ GeV. We separate the interaction into two regions marked by an elementarity…
A method is presented which makes considerably more transparent possible patterns behind low-energy scattering data. In particular, structures associated with resonances, such as locations, widths and heights, become visible with a naked…
Starting from hyperbolic dispersion relations, we present a system of Roy--Steiner equations for pion Compton scattering that respects analyticity and unitarity requirements, gauge invariance, as well as crossing symmetry, and thus all…
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…