Temperature deformations of the mirror of a radio telescope antenna

The stress informed state of the mirror of an antenna, with a diameter of 3 m, for a radio interferometer used in space, and located in a temperature field is examined. The mirror represents a parabolic shell, consisting of 19 identical parts. The problem is based on representations of the thermoelasticity of thin shells

Model-independent view on the low-mass proton-antiproton enhancement

We present a simple interpretation of the recently observed near-threshold proton-antiproton enhancement. It is described by a set of low-energy parameters deduced from the analysis of NantiN experiments at LEAR. We predict a related effect in photoproduction reaction under study by CLAS collaboration.Comment: 10 pages, 2 figure

Distribution amplitudes and decay constants for (π,K,ρ,K∗)(\pi,K,\rho,K^*) mesons in light-front quark model

We present a calculation of the quark distribution amplitudes(DAs), the Gegenbauer moments, and decay constants for $\pi,\rho,K$ and $K^*$ mesons using the light-front quark model. While the quark DA for $\pi$ is somewhat broader than the asymptotic one, that for $\rho$ meson is very close to the asymptotic one. The quark DAs for $K$ and $K^*$ show asymmetric form due to the flavor SU(3)-symmetry breaking effect. The decay constants for the transversely polarized $\rho$ and $K^*$ mesons($f^T_\rho$ and $f^T_{K^*}$) as well as the longitudinally polarized ones($f_\rho$ and $f_{K^*}$) are also obtained. Our averaged values for $f^T_V/f_V$, i.e. $(f^T_\rho/f_\rho)_{\rm av}=0.78$ and $(f^T_{K^*}/f_{K^*})_{\rm av}=0.84$, are found to be consistent with other model predictions. Especially, our results for the decay constants are in a good agreement with the SU(6) symmetry relation, $f^T_{\rho(K^*)}=(f_{\pi(K)}+f_{\rho(K^*)})/2$.Comment: 12 pages, 6figure

Polarization effects in the reaction e++e−→ρ++ρ−e^++e^-\to \rho^+ +\rho^- and determination of the ρ−\rho - meson form factors in the time--like region

The electron positron annihilation reaction into four pion production has been studied, through the channel $e^++e^-\to \bar \rho+\rho$. The differential (and total) cross sections and various polarization observables for this reaction have been calculated in terms of the electromagnetic form factors of the corresponding $\gamma^*\rho\rho$ current. The elements of the spin--density matrix of the $\rho -$meson were also calculated. Numerical estimations have been done, with the help of phenomenological form factors obtained in the space--like region of the momentum transfer squared and analytically extended to the time-like region.Comment: 19 pages, 2 figures, to appear in Phys Rev

Electromagnetic Structure of the ρ\rho Meson in the Light-Front Quark Model

We investigate the elastic form factors of the rho meson in the light-front quark model(LFQM). With the phenomenologically accessible meson vertices including the one obtained by the Melosh transformation frequently used in the LFQM, we find that only the helicity $0\to 0$ matrix element of the plus current receives the zero-mode contribution. We quantify the zero-mode contribution in the helicity $0\to 0$ amplitude using the angular condition of spin-1 system. After taking care of the zero-mode issue, we obtain the magnetic($\mu$) and quadrupole($Q$) moments of the rho meson as $\mu=1.92$ and $Q=0.43$, respectively, in the LFQM consistent with the Melosh transformation and compare our results with other available theoretical predictions.Comment: 14pages, 5figure

Photodisintegration of aligned deuterons at astrophysical energies using linearly polarized photons

Following the model independent approach to deuteron photodisintegration with linearly polarized $\gamma-$rays, we show that the measurements of the tensor analyzing powers on aligned deuterons along with the differential cross section involve five different linear combinations of the isovector $E1^j_v; j=0,1,2$ amplitudes interfering with the isoscalar $M1_s$ and $E2_s$ amplitudes. This is of current interest in view of the recent experimental finding \cite{blackston1} that the three $E1^j_v$ amplitudes are distinct and also the reported experimental observation \cite{sawatzky} on the front-back (polar angle) asymmetry in the differential cross section.Comment: 12 page