相关论文: BELLE Data on the $\pi^0 \gamma* \gamma$ Form Fact…
The recent measurement of the tau -> Ks pion nu_tau spectrum by the Belle Collaboration provides the frame to set forth a theoretical description of the decay, which is based on the contributing vector F_+(s) and scalar F_0(s) form factors.…
Confronted with some surprising claims about experimentally measured or theoretically expected dependencies on the involved momentum transfer of various form factors of pseudoscalar mesons, we reassess the present status of these quantities…
The behaviour of the pion transition form factor for the process $\gamma^\star\gamma \to \pi^0$ and $\gamma^\star\gamma^\star\to \pi^0$ at space-like values of photon momenta is estimated within the nonlocal covariant quark-meson model. The…
Online controlled experiments, now commonly known as A/B testing, are crucial to causal inference and data driven decision making in many internet based businesses. While a simple comparison between a treatment (the feature under test) and…
We investigate the $(\pi^0,\eta,\eta')\to\gamma^*\gamma$ transitions both for the spacelike region and the timelike region using the light-front quark model (LFQM). In particular, we present the new direct method to explore the timelike…
The new CLEO and LEP data on the eta-gamma and eta'-gamma transition form factors have renewed the interest in simple interpolation formulas, valid at any value of momentum transfer. We are going to show that recent theoretical and…
A theoretical description of the differential decay spectrum for the decay tau- -> nu_tau K_S pi-, which is based on the contributing K pi vector and scalar form factors F_+^{K pi}(s) and F_0^{K pi}(s) being calculated in the framework of…
We develop a QCD sum rule analysis of the form factor $F_{\gamma^*\gamma^*\pi^0}(q^2,Q^2)$ in the region where virtuality of one of the spacelike photons is small $q^2 \ll 1 GeV^2$ while another is large: $Q^2 \gapprox 1 GeV^2$. We…
Functional data play a pivotal role across science and engineering, yet their infinite-dimensional nature makes representation learning challenging. Conventional statistical models depend on pre-chosen basis expansions or kernels, limiting…
The elastic and $\gamma \to \pi$ transition form factors of the pion along with its usual static observables are calculated within a light-front field approach to the constituent quark model. The focus of this exercise in a simple model is…
We measure the dependence of $\bar B^0 \to D^{*+}e^-\bar{\nu}_e$ on the decay angles and momentum transfer. The data sample consists of $\sim 86 \times 10^6$ $B\bar B$-pairs accumulated on the $\Upsilon(4{\rm S})$ resonance by the BABAR…
Motivated by the growing importance of fidelity in quantum critical phenomena, we establish a general relation between fidelity and structure factor of the driving term in a Hamiltonian through a newly introduced concept: fidelity…
We report a determination of the CKM angle $\phi_{3}$, also known as $\gamma$, from a combination of measurements using samples of up to 711~fb$^{-1}$ from the Belle experiment and up to 362~fb$^{-1}$ from the Belle II experiment. We…
We argue that high-quality data on the reaction $e^+e^-\to \pi^+\pi^-\eta$ will allow one to determine the doubly-virtual form factor $\eta\to \gamma^*\gamma^*$ in a model-independent way with controlled accuracy. This is an important step…
We discuss the effects of fixing the winding number in quantum Monte Carlo simulations. We present a simple geometrical argument as well as strong numerical evidence that one can obtain exact ground state results for periodic boundary…
It is shown that a chiral quark model of the Nambu--Jona-Lasinio type can be used to describe "soft"-momenta parts of the amplitudes with large momentum transfer. As a sample, the processes \gamma^* --> \gamma (\pi,\eta,\eta') where one of…
Precision tests of the Standard Model using $\beta$ decay have always relied on a careful choice of transition to minimize residual nuclear structure uncertainties. Following breakthroughs in nucleon-level radiative corrections in the last…
The method of light-cone QCD sum rules is applied to the calculation of the form factors of $\gamma^*\rho \to \pi$ and $\gamma^*\gamma \to \pi^0$ transitions. We consider the dispersion relation for the $\gamma^*(Q^2)\gamma^*(q^2) \to…
We briefly review the recent experimental results on possible variations of the fine structure constant $\alpha$ on the cosmological time scale and its position dependence. We outline the theoretical grounds for the assumption that $\alpha$…
We generalize a recent model-independent form factor parameterization derived from rigorous dispersion relations to include constraints from data in the timelike region. These constraints dictate the convergence properties of the…