Related papers: Two photon width of eta_c
Based on a QED Lagrangian with additional photon-photon coupling an explicit bound state description is presented, attempting a physical correct and parameter free description of free particles. Applied to p-e- and e+-e- systems, with a…
The physical reasons in favour of a two dimensional topological model of quantum electrodynamics are discussed. It is shown that in accord with this model there is a new uncertainty relation for photon which is compatible with QED.
Prompted by several potential tetraquark states that have been reported by the LHCb, CMS and ATLAS collaborations in the di-$J/\Psi$ and $J/\Psi \Psi(2S)$ spectra, we investigate their contribution to two-photon processes. Within a…
Both the mass spectra and the wave functions of the light pseudoscalar ($\pi,K,\eta,\eta'$) and vector($\rho,K^{*},\omega,\phi$) mesons are analyzed within the framework of the light-cone constituent quark model. A gaussian radial wave…
In this work, we illustrate the recently introduced concept of the cavity Born-Oppenheimer approximation for correlated electron-nuclear-photon problems in detail. We demonstrate how an expansion in terms of conditional electronic and…
We study the photon spectrum line-shape of the $J/\psi \to \gamma\eta_c\to \gamma X$ decay process in a nonrelativistic effective field theory (EFT) framework of quantum chromodynamics (QCD). We take into account the finite width of the…
There has long been speculation about the nature of the $\sigma$-resonance. For three decades Jaffe has argued for a tetraquark composition, while others have claimed it is largely a glueball. A key pointer to its nature is its coupling to…
We employ a cascaded system approach to numerically simulate the interaction of photon pulses with a two-level scatterer in a chiral waveguide QED setup. It is possible to expand any pure state of two photons as a superposition of…
This is the second one of a series of four papers devoted to a first calculation of the scalar and spinor QED four-photon amplitudes completely off-shell. We use the worldline formalism which provides a gauge-invariant decomposition for…
Using a recently proposed method arXiv:1910.11597 (Yu Meng et al.), we study the two-photon decay rate of $\eta_c$ using two $N_f=2$ twisted mass gauge ensembles with lattice spacings $0.067$fm and $0.085$fm. The results obtained from these…
A truncated partial wave analysis for the photoproduction of two pseudoscalar mesons on a nucleon is discussed with respect to the determination of a complete set of observables. For the selection of such a set we have applied a criterion…
Recently obtained polarized target and photon asymmetry data in eta photoproduction are shown to be very powerful, in conjunction with the differential cross-section data, in yielding model-insensitive constraints on the electrostrong…
We present a realistic lattice QCD study on low-energy $N$-$J/\psi$ and $N$-$\eta_c$ interactions based on (2+1) flavor configurations with nearly physical pion mass $m_\pi=146$ MeV. The interactions, extracted from the spacetime…
We measure the cross section of $e^+e^-\rightarrow\eta_c J/\psi$ at the $\Upsilon(nS) (n=1$ -- $5)$ on-resonance and 10.52 GeV off-resonance energy points using the full data sample collected by the Belle detector with an integrated…
Properties of $2^{-+}$ charmonium $\eta_{c2}$ are investigated in quenched lattice QCD. The mass of $\eta_{c2}$ is determined to be 3.80(3) GeV, which is close to the mass of $D$-wave charmonium $\psi(3770)$ and in agreement with quark…
The excitation spectrum of the nucleon consists of several overlapping resonances. To identify these resonances and their contributions to the measured cross sections, a partial wave analysis is used. A set of at least eight, well chosen,…
We discuss a possibility of detecting a coherent photon pair emission and related radiative neutrino pair emission from excited atoms. It is shown that atoms of lambda- and ladder-type three level system placed in a pencil-like cylinder…
The properties of the d-wave superconducting state in the two-dimensional system have been studied. It has been assumed, that the pairing mechanism is based on the electron-phonon and the electron-electron-phonon interactions. The obtained…
We study the process $\gamma \gamma \to J/\psi \omega$ using a data sample of 519.2 $fb^{-1}$ recorded by the BaBar detector at SLAC at the PEP-II asymmetric-energy $e^+ e^-$ collider at center-of-mass energies near the $\Upsilon(nS)$ ($n =…
After operations at the LHC and e^+e^- Linear Colliders it may be found that a Standard-Model-like scenario is realized. In this scenario no new particle will be discovered, except a single Higgs boson having partial widths or coupling…