Related papers: New interactions in the radiative pion decay
The weak decays of hyperons and hypernuclei are studied from the chiral symmetry viewpoint. The soft pion relations are useful in understanding the isospin properties of the weak hyperon decays. Recent development on the short-range part of…
The behavior of the pion dispersion relation in a pion medium is strongly modified by the introduction of a finite chemical potential associated to the finite pion number density. Such behavior is particularly important during the hadronic…
We consider the three CP-conserving dimension-6 operators that encode the leading new-physics effects in the triple gauge couplings. The contributions to the standard-model electromagnetic dipole and semi-leptonic vector and axial-vector…
We complement studies of the neutral pion transition form factor pi^0 --> gamma^(*) gamma^(*) with calculations for the electromagnetic decay widths of the processes pi^0 --> e^+ e^-, pi^0 --> e^+ e^- gamma and pi^0 --> e^+ e^- e^+ e^-.…
The electric ${\alpha}_{\pi}$ and magnetic $\beta_{\pi}$ charged pion Compton polarizabilities are of fundamental interest in the low-energy sector of quantum chromodynamics (QCD).They are directly linked to the phenomenon of spontaneously…
The excess of electron-like events measured by MiniBooNE challenges our understanding of neutrinos and their interactions. We review the status of this open problem and ongoing efforts to resolve it. After introducing the experiment and its…
We evaluate the two pion decay of the Roper resonance in a model where explicit re-scattering of the two final pions is accounted for by the use of unitarized chiral perturbation theory. Our model does not include an explicit $\epsilon$ or…
We study the effect of anomalous Wtb couplings on the B -> Xs gamma branching ratio. The considered couplings are introduced as parts of gauge-invariant dimension-six operators that are built out of the Standard Model fields only. One-loop…
The N*(1440) -> N pi pi decay is studied by making use of the chiral reduction formula. This formula suggests a scalar-isoscalar pion-baryon contact interaction which is absent in the recent study of Hern{\'a}ndez et al. The contact…
We discuss the decay tau^- -> nu_tau pi^- pi^0 gamma in terms of a model with the correct low-energy structure and with the relevant resonance degress of freedom. The nontrivial radiative dynamics becomes visible for large photon momenta…
The neutrino produced in the pion decay reveals a new diffraction phenomenon due to many-body interactions in an intermediate time region when wave functions of the parent and daughters overlap. Because of diffraction, the probability to…
Probing signatures of anomalous interactions of the Higgs boson with pairs of weak vector bosons is an important goal of an $e^+e^-$ collider commissioned as a Higgs factory. We perform a detailed analysis of such potential of a collider…
Recent analyses of low-energy pion-nucleon experimental data have provided clear evidence for the violation of the isospin symmetry of the strong interaction. In the present work, it is shown that the single-charge-exchange reaction is the…
In the present paper we explore various dynamical scenarios for New Physics (NP) which could be generated by very heavy particles and observed in the form of non-standard "low energy" interactions affecting the scalar sector, the gauge…
We present the sensitivity limits on the coefficients of a dimension-6 effective operators that parametrizes the possible effects of new physics beyond the Standard Model. Our results are based on the study of the processes $e^+ e^- \to W^+…
We analyze the possibility of experimental investigation of new low-energy relations between the values of resonance masses in the meson form factors and the differential rate of radiative kaon decay $K^+\to \pi^+ e^+e^-(\mu^+\mu^- )$ at…
We have measured the $\pi^+\to {\rm e}^+\nu\gamma$ branching ratio over a wide region of phase space, based on a total of 65,460 events acquired using the PIBETA detector. Minimum-$\chi^2$ fits to the measured $(E_{e^+},E_\gamma)$ energy…
The mass and the decay width of a Higgs boson in the minimal standard model are evaluated by a variational method in the limit of strong self-coupling interaction. The non-perturbative technique provides an interpolation scheme between…
Surprisingly, until recently CP violation in pion decay was not ruled out experimentally even at the percent level. I have derived the first experimental limit, $-0.01<A_{CP}<0.02$, from old data on the anomalous magnetic moment $g-2$ of…
The "pion-decay" bump is a distinct signature of the differential energy spectrum of $\gamma$-rays between 100 MeV and 1 GeV produced in hadronic interactions of accelerated particles (cosmic rays) with the ambient gas. We use the recent…