Related papers: Light-by-light scattering sum rules constraining m…
At leading-twist accuracy the form factors for the transitions from a virtual photon to the $\eta$ or $\eta'$ can be expanded into a power series of the variable $\omega$, being related to the difference of two photon virtualities. The…
The radiative $\Delta \to \gamma N$ transition is examined at the real photon point $Q^2=0$ using the framework of light-cone QCD sum rules. In particular, we determine the sum rules for the transition form factors $G_M(0)$ and $R_{EM}$ up…
The on-shell matrix elements, or couplings $g_{H H^*(H_1)\gamma}$, describing the $B(D)_q^* \to B(D)_q \gamma$ and $B_{1 q} \to B_q \gamma$ ($q = u,d,s$) radiative decays, are determined from light-cone sum rules at next-to-leading order…
The surprising results by the BarBar collaboration on the $\pi\gamma$ transition form factor require new thoughts about the high-$Q^2$ dependence of the form factors with virtual photons. We make use of the anomaly sum rule [J. Horejsi and…
We suggest a new approach for calculating heavy-to-light form factors. The method is based on light cone sum rules (LCSR) and covers the whole kinematical range of momentum transfer. The derivation of the new sum rule uses a suitable…
In the present work, we analyze the properties of the transition form factors (TFFs) for the $\gamma\gamma^*\to \eta^{(\prime)}$ process, employing the $\eta^{(\prime)}$-meson light-cone distribution amplitude (LCDA) derived within the…
The transition form factors of $B_{(s)} \to S$, with $S$ denoting a scalar meson, are investigated in the light-cone sum rules approach. The numerical values are approximately twice as large as that estimated in the light-front quark model…
We revisit QCD sum rules for the decay constants of heavy-light mesons. In the sum rules for the vector mesons B^*_(s) and D^*_(s) we improve the accuracy of OPE, taking into account the O(alpha_s^2) terms in the perturbative part and…
The physics of light-matter interactions is strongly constrained by both the small value of the fine-structure constant and the small size of the atom. Overcoming these limitations is a long-standing challenge. Recent theoretical and…
Based on analyticity, unitarity, and Lorentz invariance the contribution from hadronic vacuum polarization to the anomalous magnetic moment of the muon is directly related to the cross section of e^+e^- --> hadrons. We review the main…
Though the predictions of the Standard Model (SM) are in excellent agreement with experiments there are still several theoretical problems, such as fine-tuning and the hierarchy problem. These problems are associated with the Higgs sector…
In this article, we calculate the form-factors of the transitions $B \to a_1(1260)$, $b_1(1235) $ in the leading-order approximation using the light-cone QCD sum rules. In calculations, we choose the chiral current to interpolate the…
I present a mini-review of the masses and couplings of the bare (unmixed) light scalar mesons : $\bar qq, (\overline{qq})(qq), (\bar qq)(\bar qq), gg$ from QCD spectral sum rules (QSSR) and low-energy theorems (LET) which we compare with…
We present the results of our recent analysis of the meson-photon transition form factors $F_{P\gamma}(Q^2)$ for the pseudoscalar mesons $P = \pi^0,\eta,\eta',\eta_c$, using the local-duality version of QCD sum rules.
We present the first complete results for the semileptonic and rare radiative form factors of B-mesons weak decay into a light vector-meson (rho, omega, K*, phi) in the light-cone sum-rule approach. The calculation includes radiative…
We study the transition form factors of the light vector to pseudoscalar mesons as functions of the momentum transfer $q^2$ within the light-front quark model. With these form factors, we calculate the decay branching ratios of all possible…
The advent of a next linear $e^\pm e^-$ collider and back-scatterd laser beams will allow the study of a vast array of high energy processes of the Standard Model through the fusion of real and virtual photons and other gauge bosons. As…
Evidence for light-by-light (LbL) scattering, $\gamma\gamma\to\gamma\gamma$, in ultraperipheral PbPb collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV is reported. LbL scattering processes are selected in events with just…
We have analyzed the $B\to \pi $ and $B_{s}\to K$ semileptonic form factors and $B\to V\gamma (V=K^*,\rho,\omega)$ processes in the light-cone QCD sum rules. In order to enhance the predictivity and reliability of numerical results the…
Scattering relativistic electrons with optical lasers can result in a significant frequency upshift for the photons, potentially producing $\gamma$-rays. This is what linear Compton scattering taught us. Ultra-intense lasers offer nowadays…