Related papers: On the CVC problem in tau-decay
The preliminary results of PIBETA experiment strongly suggest the presence of non V-A anomalous interactions in the radiative pion decay. Without a guiding idea about the nature of these new interactions it is very difficult to interpret…
Recently a strong indication for a deviation from the standard model (SM) has been obtained by PIBETA Collaboration. Namely, SM fails to describe the energy distribution and the branching ratio of the radiative decays of the positive pions…
The recent results of the PIBETA experiment strongly suggest the presence of a non-(V-A) anomalous interaction in the radiative pion decay. The same interaction should inevitably contribute to the neutron decay and in particular it should…
We report interim results of the PIBETA experiment analysis for the pion beta decay and pion radiative decay. The former is in excellent agreement with the SM predictions at the 1% accuracy level.
Bose-Einstein correlations of pairs of identical charged pions produced in hadronic Z decays and in 7 TeV pp minimum bias interactions are investigated within the framework of the tau-model.
We find that, in the local V-A theory, the radiative corrections to pion beta-decay involving the weak vector current, when evaluated in the current algebra (CA) formulation in which quarks are the fundamental underlying fields, show a…
We present a new method to measure the transverse spin correlation in the $H\to\tau^+\tau^-$ decay. The method has been devised to be insensitive to the beamstrahlung which affects the definition of the beam energy at a linear collider. In…
I consider some selected topics in chiral perturbation theory (CHPT) as probed at colliders such as DA$\Phi$NE. Emphasis is put on processes involving pions in the isospin zero S-wave which require multi-loop calculations. These include the…
The $\eta'$ meson is associated with the U(1) anomaly. In this paper, a successful effective chiral theory of mesons has been applied to study the anomalous decay of $\eta'\rightarrow \pi^+\pi^-\pi^{+(0)}\pi^{-(0)}$. In this study, the…
We analyse tau -> (3 pions) nu_tau decays within the framework of the resonance chiral theory of QCD. We have worked out the relevant Lagrangian that describes the axial-vector current hadronization contributing to these processes, and the…
A reanalysis of the radiative pion decay together with the calculation of the radiative corrections within chiral perturbation theory (CHPT) is performed. The amplitude of this decay contains an inner Bremsstrahlung contribution and a…
We review two manifestations of chiral symmetry breaking in the pion sector. First, we examine the $\pi\pi$ scattering amplitude at threshold, which is completely determined by the chiral symmetry breaking part of the strong interaction,…
A study is presented of anomalous HVV interactions of the Higgs boson, including its $CP$ properties. The study uses Higgs boson candidates produced mainly in vector boson fusion and gluon fusion that subsequently decay to a pair of $\tau$…
f large fluctuations of quark chirality occur in heavy ion collisions, they result in macroscopic CP-odd "spots" of the so called theta-vacua, with a non-zero $\theta(x)$. We consider particular decays of mesons, CP-forbidden in the vacuum…
We study the possible signals of a pion string associated with the QCD chiral phase transition in LHC Pb - Pb collision at energy $ \sqrt{s}=5.5$ TeV. In terms of the Kibble-Zurek mechanism we discuss the production and evolution of the…
We show that a simple and reasonable generalization of the anomalous interaction between the neutral pion and two photons can induce the C-violating three photon decay of the neutral pion in noncommutative quantum electrodynamics. We find…
The interplay between the chiral anomaly and the strong magnetic or vortical fields created in noncentral heavy-ion collisions can lead to various anomalous chiral effects in the quark--gluon plasma, including the chiral magnetic effect…
Within the framework of chiral perturbation theory with virtual photons and leptons, we present an updated analysis of the pionic beta decay including all electromagnetic contributions of order e**2 p**2. We discuss the extraction of the…
We have revisited the isospin-breaking corrections relating $\sigma(e^+e^-\to\pi^+\pi^-)$ and $\Gamma(\tau^-\to\pi^-\pi^0\nu_\tau)$. We confirm that the associated uncertainty is under control, so that tau data can also be used to predict…
In case of chiral U_A(1) symmetry restoration the mass of the eta' boson (the ninth, would-be Goldstone boson) is decreased, thus its production cross section is heavily enhanced. The eta' decays (through one of its decay channels) into…