Related papers: \eta and \eta' transition form factors from ration…
For the first time, a phenomenological analysis of the experimental electromagnetic form factors of the nucleon, both in the timelike and spacelike regions, is performed by taking into account the effects of nonvalence components in the…
We investigate the possibility to constrain the pion distribution amplitude from the gamma* gamma* -> pi transition. For a surprisingly large range in the two photon virtualities we find that the transition form factor is essentially…
The $\Delta-N$ electromagnetic transition form factors are calculated in the Poincar\'e covariant quark model in three forms of relativistic kinematics. Addition of $D-$state components to pure $S-$state model wave functions, chosen so as…
Assuming simple properties of the spectator particle in weak decays the form factors of hadronic current matrix elements are shown to be related to a single universal function. The Isgur-Wise result for heavy-to-heavy transitions follows as…
We study the $\eta'-g^*-g$ transition form factor by using the $\eta'$ wave function constrained by the experimental data on the $\eta'-\gamma^*-\gamma$ transition form factor provided by CLEO and L3 . We also take into account the…
Changes in the values of the fundamental constants mu, the proton to electron mass ratio, and alpha, the fine structure constant due to rolling scalar fields have been discussed both in the context of cosmology and in new physics such as…
In this work, the electromagnetic and gravitational form factors of $\Delta$ isobars, as well as the electromagnetic $N-\Delta$ transition form factors are studied systematically and continuously using a covariant quark-diquark approach…
We report calculations of space-like electromagnetic form factors and charge radii of pseudoscalar mesons, covering both light and heavy-light flavour sectors within a flavour-dependent Bethe-Salpeter framework.
It is reported on a leading-twist analysis of the eta - photon and eta' - photon transition form factors. The analysis allows for an estimate of the lowest Gegenbauer coefficients of the quark and gluon distribution amplitudes.
I discuss recent applications of QCD light-cone sum rules to various form factors of pseudoscalar mesons. In this approach both soft and hard contributions to the form factors are taken into account. Combining QCD calculation with the…
Extensive Monte Carlo simulations are used to investigate the low-temperature properties of the random anisotropy Heisenberg model, which describes the magnetic behavior of amorphous rare-earth-transition metal alloy. We show that the…
The form factors for the weak currents between B and light mesons are studied by relating them to the corresponding D form factors at q^2_{max} according to HQET, by evaluating them at q^2=0 by QCD sum rules, and by assuming a polar q^2…
A new resummation of the $S$-factor of a composite system of two relativistic spin-1/2 particles of arbitrary masses interacting via a Coulomb-like chromodynamical potential is presented. The analysis is performed in the framework of a…
We define geometric critical exponents for systems that undergo continuous second order classical and quantum phase transitions. These relate scalar quantities on the information theoretic parameter manifolds of such systems, near…
We compute three-loop corrections of $\mathcal{O}(\alpha_{s}^3)$ to form factors with one massive and one massless quark coupling to an external vector, axialvector, scalar, pseudoscalar, or tensor current. We obtain analytic results for…
Electromagnetic form factors serve to explore the intrinsic structure of nucleons and their strangeness partners. For the decay $\Sigma^0\to\Lambda e^+e^-$, due to limited phase space, the effects caused by the Sigma-to-Lambda transition…
Form factors of a simple system have been calculated in various forms of relativistic quantum mechanics, using a single-particle current. Their comparison has shown large discrepancies. The comparison is extended here to instant- and…
We present several recent results from the BaBar collaboration in the areas of initial state radiation physics and transition form factors. An updated study of the processes e+e- -> K+K-pi+pi- and e+e- -> K+K-pi0pi0 provides an improved…
We present comprehensive calculations of the electromagnetic form factors, including the charge, magnetic-dipole, electric-quadrupole and magnetic-octupole form factors, of the $\Omega^-$ in the spacelike region using the quark-diquark…
In semi-leptonic and other weak decays of mesons, the hadronic matrix elements of the operators in the weak Hamiltonian are parametrized by standard sets of independent, Lorentz invariant, form factors. For the case of pseudoscalar to…