arXiv subjects

A. I. Syamtomov

Publications and source records attributed to A. I. Syamtomov.

4 recordsLinked to original sources

arXiv2026

Non-Forward OPE Kernel versus Scalar Form Factor in Near-Threshold $J/ψ$ Photoproduction

Near-threshold $J/ψ$ photoproduction has been used to infer scalar gluonic structure from integrated cross-section data. We test whether such an inference is stable against the assumed non-forward continuation of the OPE kernel. With an exponential diffractive slope fixed, the threshold fit favors an additional scalar $G_S(t)$-like contribution. However, the residuals show a systematic $W$-dependent trend. When either the effective slope or the kernel shape is replaced by a physically motivated form-factor continuation, the trend disappears and the fitted scalar coefficient is driven to zero. Thus integrated $σ(W)$ data cannot determine the non-forward OPE kernel or isolate a scalar $G_S(t)$ contribution. Differential $dσ/dt$ data are required.

hep-ph↗

arXiv1995

Quark-exchange Effects in a Deuteron Breakup at Intermediate Energy

Microscopical approach to a deuteron breakup at high and intermediate energies is proposed. We show that the quark exchange effects, resulting from the full asymmetry of the $6q$-deuteron wave function with respect to the pair permutations of quark variables, strongly affect the proton momentum distribution in the deuteron, as well as the polarization observables of inclusive deuteron breakup, when the ``internal momentum'' in the deuteron is of order of a few hundreds MeV/c.

hep-ph↗

arXiv1994

Deuteron Electromagnetic Form Factors in the Transitional Region Between Nucleon-Meson and Quark-Gluon Pictures

Experimental observables of the elastic eD-scattering in the region of intermediate energies are discussed. We offer the analysis of the available experimental data, which reproduces the results of the calculations with popular $NN$-potentials at low energies ($Q^2\ll 1(GeV/c)^2$), but, at the same time, provides the right asymptotic behavior of the deuteron e.m. form factors, following from the quark counting rules, at high energies ($Q^2\gg 1(GeV/c)^2$). The numerical analysis developed allows to make certain estimations of the characteristic energy scale, at what the consideration of quark-gluon degrees of freedom in the deuteron becomes essential.

hep-ph↗

arXiv1994

Polarization observables of the $\vec{d} \vec{p} \rightarrow \vec{p}d$ reaction and one-neutron-exchange approximation

The polarization observables in the elastic scattering of polarized deuterons on a polarized hydrogen target, with measurement of the recoil proton polarization, are considered. The observables are calculated in the one-neutron exchange approximation, for the special case of backward scattering ($θ_{c.m.} = 180^{\circ}$). Several new relations between polarization observables of the reaction are derived within the framework of this approximation.

hep-ph↗