Related papers: Two-photon decay of a light scalar quark-antiquark…
After discussing the intrinsic ambiguity in determining the light quark mass ratio $m_u/m_d$, we reexamine the recent proposal that this ambiguity can be resolved by applying the QCD multipole expansion for the heavy quarkonium decays. It…
A precision determination of the neutral-pion width would improve determinations of the splitting between the up- and down-quark masses, and matrix elements for the decay of neutral mesons into two photons could play a role in the attempt…
The perturbative QCD approach to quarkonium decay into a photon and hadrons is reconsidered. It is shown that a consistent treatment within perturbative QCD calls for the introduction of a fragmentation contribution which has been neglected…
The orthopositronium decay to three photons is studied in the phase-space region where one of the photons has an energy comparable to the relative three-momentum of the e+e- system (w ~ m alpha). The NRQED computation in this regime shows…
With usage of obvious mechanisms of quark currents the amplitudes of leptonic decaies of pseudoscalar mesons are investigated. The estimation for a constant of leptonic decay of the D+ meson is obtained, f_D+ ~ 0.23 GeV.
The applicability of the quasi-static approximation for calculating the two-photon annihilation rate of the scalar f_0(980) meson envisaged as a K\bar K molecule is critically re-examined. It is shown that the validity of this approximation…
Two--photon decay of hydrogen--like ions is studied within the framework of second--order perturbation theory, based on relativistic Dirac's equation. Special attention is paid to the effects arising from the summation over the…
The present talk consists of two parts. The first one is allocated for consideration of the dimension of bilocal meson fields for quark-antiquark meson systems, which have been so far treated as the bosonic fields independent of constituent…
We calculate the two-body decay rates of "quirkonium" states formed from quirks that acquire mass solely through electroweak symmetry breaking. We consider SU(N)_ic infracolor with two flavors of quirks transforming under the electroweak…
Semileptonic decays of heavy baryons consisting of one heavy (Q=b,c) and two light (q=u,d,s) quarks are considered in the heavy-quark--light-diquark approximation. The relativistic quasipotential equation is used for obtaining masses and…
The axion is a hypothetical elementary particle and a cold dark matter candidate. It could dominate potential wells of most astrophysical objects. Axions spontaneously decay into nearly monochromatic microwave photons. We present results…
Agreement of theoretical calculations with the observed production rate of bottom quarks at hadron colliders is improved by the introduction of a contribution from pair-production of light gluinos, of mass 12 to 16 GeV, having two-body…
Two topics are briefly reviewed in this talk: the decay of flavored hadrons or quarkonium states involving a baryon--antibaryon pair, and the spectroscopy of heavy baryons containing one, two or three heavy quarks. Some prospects for exotic…
We perform non-perturbative calculation of the \pi^0 to {\gamma}{\gamma} transition form factor and the associated decay width using lattice QCD. The amplitude for two-photon final state, which is not an eigenstate of QCD, is extracted…
The process AB --> Quarkonium + photon + X, for a heavy quarkonium state such as J/psi or Upsilon, is considered. The ratio of the cross-sections for this process in pp and pp(bar) collisions is shown to be a vary sensitive probe of models…
Semileptonic decays of heavy baryons consisting of one heavy (Q=b,c) and two light (q=u,d,s) quarks are considered in the heavy-quark--light-diquark approximation. The relativistic quasipotential equation is used for obtaining masses and…
Yang's theorem states that an initial J=1 state cannot decay into two photons. Because of this result some reactions relating to elementary particles or atomic transitions can be ruled out. The theorem is not valid in the presence of…
Phenomenology of uncolored iquarks - hypothetical fermions charged under a new confining unbroken non-abelian gauge group as well as the standard electroweak gauge group - is investigated for the iquark mass in the range near and above 100…
We present a full account of the two-loop electroweak, two-photon mediated short-distance dispersive $K_L \to\mu^+\mu^-$ decay amplitude. QCD corrections change the sign of this amplitude and reduce it by an order of magnitude. Thus, the…
We discuss processes leading to two photon final states in peripheral heavy ion collisions at RHIC. Due to the large photon luminosity we show that the continuum subprocess $\gamma \gamma \to \gamma \gamma$ can be observed with a large…