Related papers: Rescattering effects in eta {\to} 3pi decays
The cusp effect in K \to 3\pi and data on K_e4 decays allow one to extract experimental information on the elastic \pi\pi scattering amplitude near threshold, and to confront the outcome of the analyses with predictions made in the…
The charged $K_{\ell 4}$ decay, $K^+\to\pi^+\pi^-\ell^+\nu_{\ell}$ is studied in the framework of chiral perturbation theory based on the effective Lagrangian including mesons, photons, and leptons. We give analytic expressions for the two…
Rates for particle interaction processes and decays will be modified in a Lorentz-violating quantum field theory, because of changes to the particle kinematics$-$particularly through the modified dispersion relations affecting the outgoing…
A precision measurement of the matrix elements for $\eta\to\pi^+\pi^-\pi^0$ and $\eta\to\pi^0\pi^0\pi^0$ decays is performed using a sample of $(10087\pm44)\times10^6$ $J/\psi$ decays collected with the BESIII detector. The decay $J/\psi…
We have searched for the rare decays of the eta prime meson to e+ e- eta, e+ e- pizero, e+ e- gamma, and e mu in hadronic events at the CLEO II detector. The search is conducted on 4.80 fb^-1 of e+ e- collisions at the Cornell Electron…
We examine the ratio of the decay rate of the eta_c into light hadrons to the decay rate into photons and find that most of the large next-to-leading-order (NLO) correction is associated with running of the strong coupling alpha_s. We resum…
In this master thesis I discuss how the weak three-body decay B^+ --> pi^- pi^+ K^+ is related to the strong interactions between the final-state particles. Current issues in hadron spectroscopy define a region of interest in a Dalitz plot…
In this paper we perform an amplitude analysis of $\eta'\to\pi^+\pi^-\gamma$ and confront it with the latest BESIII data. Based on the final-state interaction theorem, we represent the amplitude in terms of an Omn\'es function multiplied by…
The elastic pi-N scattering amplitude in the isospin limit is calculated in the framework of heavy baryon chiral perturbation theory, up to the third order. Threshold parameters like scattering lengths, volumes, effective ranges, etc. are…
1. Introduction: a) motivations, b) status, c) purpose, d) results 2. Kinematics and couplings 3. Decay amplitude (analytic expression): a) tree level, b) one loop 4. Decay width (numerical): a) diphoton energy spectrum [energy cut] 5.…
We analyze the hadronic uncertainty from light-quark loops coupled to (anti)neutrino in low-energy neutral-current (anti)neutrino scattering, estimated at the $3$-$4$ permille level. This uncertainty arises from limited knowledge of the…
We study the decay K^+ -> pi^+ pi^0 e^+ e^-, currently under analysis by the NA62 Collaboration at CERN. In particular, we provide a detailed analysis of the Dalitz plot for the long-distance, gamma^*-mediated, contributions…
We examine the results of Chiral Effective Field Theory ($\chi$EFT) for the scalar- and spin-dipole polarisabilities of the proton and neutron, both for the physical pion mass and as a function of $m_\pi$. This provides chiral…
Using the analysis of ChPT to two loops, we perform an error analysis of the threshold and low energy parameters, based on the uncertainties for the one loop low energy parameters and the resonance saturation mechanism. Different sets of…
Using the BaBar measurements of the Dalitz plots for the decays $B^0 \to K^+\pi^0\pi^-$, $B^0 \to K^0\pi^+\pi^-$, $B^+ \to K^+\pi^+\pi^-$, $B^0 \to K^+ K^0 K^-$, and $B^0 \to K^0 K^0 \bar K^0$, we demonstrate that it is possible to cleanly…
We present a new determination of the parity of the neutral pion via the double Dalitz decay pi^0 -> e+ e- e+ e-. Our sample, which consists of 30511 candidate decays, was collected from K_L -> pi0 pi0 pi0 decays in flight at the KTeV-E799…
We present a calculation of the decays $\eta^{(')}\to\pi^+\pi^-\gamma^{(\ast)}$ at the one-loop level up to and including next-to-next-to-leading order (NNLO) in large-$N_c$ chiral perturbation theory. The numerical evaluation of the…
We predict neutron-proton scattering cross-sections and polarization observables up to next-to-next-to-next-to leading order in a renormalization-group invariant description of the strong nucleon-nucleon interaction. Low-energy constants…
The CP conserving amplitudes for the decays $K\to3\pi$ are calculated in Chiral Perturbation Theory. The calculation is made at the next-to-leading order including strong and local electromagnetic isospin breaking. A comparison is made…
We calculate the nucleon-nucleon scattering amplitudes in the 1S0 and 3S1-3D1 channels at next-to-next to leading order starting from a recently proposed non-relativistic chiral effective theory, which includes dibaryon fields as…