Related papers: Precise strength of th piNN coupling constant
Sum rules for the nonperturbative piece of correlators (specifically, the vector current correlator) are discussed. The sum rule subtracting the perturbative part is of the superconvergent type. Thus it is dominated by the bound states and…
The COMPASS collaboration at CERN has investigated pion Compton scattering, $\pi^-\gamma\rightarrow \pi^-\gamma$, at centre-of-mass energy below 3.5 pion masses. The process is embedded in the reaction…
By matching the world of hadrons to that of some effective chiral quark theory, we determine the induced condensates for QCD sum rules in the presence of an external pion field. The observed values of the strong and weak $\pi NN$ coupling…
We discuss two precision experiments which will measure fundamental weak interaction parameters: MuLAN's goal is the measurement of the positive muon lifetime to 1 ppm, which will in turn determine the Fermi coupling constant G_F to 0.5 ppm…
Polarized beam gamma p Compton scattering provides a theoretically clean way to extract the isovector parity violating pion-nucleon coupling constant $h_{\pi NN}^{(1)}$. This channel is more tractable experimentally than the recently…
The forward neutron production in the ep collisions at 300 GeV measured by H1 and ZEUS Collaborations at DESY has been used to estimate the total probability for proton fluctuation into n pi^+ and p pi^0. The probability found is on the…
Astrophysical tests of the stability of fundamental couplings are becoming an increasingly important probe of new physics. Motivated by the recent availability of new and stronger constraints we update previous works testing the consistency…
We determine the values of the one- and two-loop low energy constants appearing in the SU(2) Chiral Perturbation Theory calculation of pion-pion scattering. For this we use a recent and precise sum rule determination of some scattering…
We calculate (g-2) of the muon and the QED coupling alpha(M_Z^2), by improving the determination of the hadronic vacuum polarization contributions and their uncertainties. We include the recently re-analysed CMD-2 data on e^+e^- -> pi^+…
The $\textit{axial coupling of the nucleon}$, $g_A$, is the strength of its coupling to the $\textit{weak}$ axial current of the Standard Model of particle physics, in much the same way as the electric charge is the strength of the coupling…
To leading order in alpha_s, the leading and non-leading 1/m_b corrections to the excited g_B^(**) meson coupling g_B^(**)BPi is calculated in the framework of QCD spectral moment sum rules in the full theory. Our prediction is in good…
We analyze forward Compton scattering, using real analytic amplitudes. By fitting the total \gamma p scattering cross section data in the high energy region 5 GeV < \sqrt s < 20 GeV, using a cross section rising as \ln^2 s, we calculate…
The SciBooNE Collaboration reports a measurement of neutral current coherent neutral pion production on carbon by a muon neutrino beam with average energy 0.8 GeV. The separation of coherent from inclusive neutral pion production has been…
Using recent CLEO III results for the cross section for $e^+e^- \to {\rm hadrons}$ at seven centre-of-mass energies between 6.964 and 10.538 GeV, we derive a value for the strong coupling constant…
New QCD sum rules for the nucleon axial-vector current coupling constants are derived. One set is derived from a generalized correlator of spin-1/2 interpolating fields, and the other with a mixed correlator of spin-1/2 and spin-3/2 fields.…
The couplings between the soft pion and the doublet of heavy-light mesons are basic parameters of the ChPT approach to the heavy-light systems. We compute the unquenched (Nf=2) values of two such couplings in the static heavy quark limit:…
The recent TRIUMF experiment for $\mu^- p \to n \nu_{\mu} \gamma$ gave a surprising result that the induced pseudoscalar coupling constant $g_P$ was larger than the value obtained from $\mu^- p \to n \nu_{\mu}$ experiment as much as 44 %.…
The SciBooNE Collaboration has performed a search for charged current coherent pion production from muon neutrinos scattering on carbon, \nu_\mu ^{12}C \to \mu^- ^{12}C \pi^+, with two distinct data samples. No evidence for coherent pion…
We extend previous work on sum rules for the invariant amplitudes of pion Compton scattering by deriving a complete lowest order perturbative spectral function - and its leading non perturbative power corr ections - for a specific…
In this article, we firstly analyze the mass and pole residue of negative parity nucleon $N^*(1535)$ within the two-point QCD sum rules. Basing on these results, we continuously study the strong coupling constants of vertices…