Time-like Gravitational Formfactors and Shear Viscosity

The gravitational formfactor similar to shear viscosity is identified. In the time-like region it corresponds to the contribution of exotic hybrid meson. The exotic quantum numbers may be considered as a counterpart of dissipation in crossed channel. The ratio of viscosity to entropy density is estimated. The smallness due to holographic bound corresponds to the relative smallness of coupling of hybrid meson and the intrinsic transverse momentum, being the dynamical counterpart of temperature.Comment: 4 pages, no figures, parallel session keynote talk at the 24th International Spin Symposium (SPIN2021

Spin effects in diffractive charmonia production

We consider exclusive double diffractive production of polarised axial-vector $\chi_c(1^+)$ and tensor $\chi_c(2^+)$ charmonia in proton-(anti)proton collisions at Tevatron energy. The corresponding amplitudes for these processes are derived within the $k_t$-factorisation approach. Contributions from different polarisation states of axial-vector and tensor charmonia are quantified. Corresponding experimental consequences are discussed.Comment: 3 pages, 3 figures, talk given at 11th International Workshop on Meson Production, Properties and Interaction, 10-15 June 2010, Krak\'ow, Polan

Nucleon spin structure at low momentum transfers

The generalized Gerasimov-Drell-Hearn (GDH) sum rule is known to be very sensitive to QCD radiative and power corrections. We improve the previously developed QCD-inspired model for the $Q^2$-dependence of the GDH sum rule. We take into account higher order radiative and higher twist power corrections extracted from precise Jefferson Lab data on the lowest moment of the spin-dependent proton structure function $\Gamma_1^{p}(Q^2)$ and on the Bjorken sum rule $\Gamma_1^{p-n}(Q^2)$. By using the singularity-free analytic perturbation theory we demonstrate that the matching point between chiral-like positive-$Q^2$ expansion and QCD operator product $1/Q^2$-expansion for the nucleon spin sum rules can be shifted down to rather low $Q\simeq\Lambda_{QCD}$ leading to a good description of recent proton, neutron, deuteron and Bjorken sum rule data at all accessible $Q^2$.Comment: 12 pages, 6 figure