Related papers: Isospin violation in pion-kaon scattering
We calculate the one--loop corrections to the Kroll--Ruderman low--energy theorems for charged pion photoproduction in the framework of heavy baryon chiral perturbation theory. We predict the threshold S--wave multipole $E_{0+}$ to be…
We compare the most used approximations to calculate the contribution from pion re-scattering mechanisms to pion production from proton-proton scattering, near threshold. Our calculation employs a pseudo-vector coupling for the pi NN vertex…
A single-spin asymmetry in the azimuthal distribution of neutral pions relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. The…
We examine the process of Compton scattering, in the presence of a Lorentz- and CPT-violating modification to the structure of the electron. We calculate the complete tree-level contribution to the cross section; our result is valid to all…
Influence of the isospin-violating (\rho^0, \omega)-mixing is discussed for any pair of decays of \rho^0, \omega into the same final state. It is demonstrated, in analogy to the CP-violation in neutral kaon decays, that isospin violation…
We examine the role of the elementary isoscalar pion--nucleon scattering amplitude in the description of the processes $pp \to pp\pi^0$ and $pp\to d\pi^+$ at threshold. We argue that the presently used tree level dimension two approximation…
Coulomb and mass difference corrections to low-energy pion-nucleon scattering are calculated and compared with previous work including potential models, dispersion relation methods and chiral perturbation theory calculations. Particular…
The polarizabilities of light pseudoscalar mesons can be extracted from differential cross sections for Compton scattering near threshold. While this has been accomplished for charged pions employing Primakoff reactions, a corresponding…
A new evaluation of the universal $\pi\pi$ scattering length relation is used to extract the $\pi\pi$ $s$-wave scattering lengths from threshold pion production data. Previous work has shown that the chiral perturbation series relating…
Isospin symmetry is well fulfilled in the QCD vacuum, as evidenced by small mass differences of isospin partners and suppressed isospin-violating decays. Recently, the NA61/SHINE collaboration reported an unexpectedly large…
We use chiral perturbation theory (ChPT) to calculate the $\pi^- d$ scattering length with an accuracy of a few percent, including isospin-violating corrections both in the two- and three-body sector. In particular, we provide the technical…
The low energy scattering of pions is investigated in the presence of electromagnetic interactions at leading order and at next-to-leading order for the amplitudes involving at most one pair of charged pions. The size of the electromagnetic…
Current predictions for the ratio of phi -> K^+K^-/K_LK_S decay rates exceed the corresponding experimental value in about five standard deviations. By far, the dominant sources of isospin breaking to this ratio are the phase-space (52%)…
The effect of isoscalar S-wave multi-channel pion-pion scattering ($\pi\pi\to\pi\pi,K\bar{K},\eta\eta$) is considered in the analysis of data on decays of the $\Upsilon$-meson family -- $\Upsilon(2S)\to\Upsilon(1S)\pi\pi$,…
It is demonstrated that there is a dynamic isospin breaking effect in the near threshold $\gamma^{*} N\to \pi N$ reaction due to the mass difference of the up and down quarks, which also causes isospin breaking in the $\pi N$ system. The…
We discuss the isospin-breaking effects on threshold cusp structures in multichannel scattering near two-body thresholds. In hadronic systems with isospin symmetry, two or more nearly degenerate thresholds can appear, and their small…
In the last few years it has become possible to study low energy pi pi scattering in kaon decays to three pions, thanks to the high statistics measurement of K+- -> pi+- pi0 pi0 decays performed by the NA48/2 experiment at the CERN SPS. At…
We summarize our lattice QCD determinations of the pion-pion, pion-kaon and kaon-kaon s-wave scattering lengths at maximal isospin with a particular focus on the extrapolation to the physical point and the usage of next-to-leading order…
CP violation is an important tool to test the Standard Model and his extensions. We describe kaon physics observables testing CP violation and more in general short distance physics. Channels under consideration will be K -> pi nu nu, K ->…
Rare Kaon decays and CP violation are important tools to test the Standard Model and its extensions. We describe kaon physics observables testing CP violation and more generally short distance physics. Channels under consideration will be K…