Spin Physics Experiments at NICA-SPD with polarized proton and deuteron beams

We propose to perform measurements of asymmetries of the Drell-Yan (DY) pairs production in collisions of non-polarized, longitudinally and transversally polarized protons and deuterons which provide an access to all leading twist collinear and TMD PDFs of quarks and anti-quarks in nucleons. The measurements of asymmetries in production of J/Psi and direct photons will be performed as well simultaneously with DY using dedicated triggers. The set of these measurements will supply complete information for tests of the quark-parton model of nucleons at the QCD twist-two level with minimal systematic errors.

An analytical review of DSPIN-13

A short analytical review of XV Workshop on High Energy Spin Physics (DSPIN-13) is given. All materials of the workshop, including all presented talks, list of participants and the pdf-file of Proceedings are available on the site http://theor.jinr.ru/~spin/2013/.

Regge trajectories in QCD

We discuss some problems concerning the application of perturbative QCD to high energy soft processes. We show that summing the contributions of the lowest twist operators for non-singlet $t$-channel leads to a Regge-like amplitude. Singlet case is also discussed.

An analytic review of DSPIN-11

A short analytical review of the main results of the DSPIN-11 Workshop (JINR, Dubna, September 20--24, 2011) is given.

TMDs in the bag model

Leading and subleading twist transverse momentum dependent parton distribution functions (TMDs) are studied in a quark model framework provided by the bag model. A complete set of relations among different TMDs is derived, and the question is discussed how model-(in)dependent such relations are. A connection of the pretzelosity distribution and quark orbital angular momentum is derived.

Azimuthal asymmetries in production of charged hadrons by high energy muons on polarized deuterium targets

Search for azimuthal asymmetries in semi-inclusive production of charged hadrons by 160 GeV muons on the longitudinally polarized deuterium target, has been performed using the 2002- 2004 COMPASS data. The observed asymmetries integrated over the kinematical variables do not depend on the azimuthal angle of produced hadrons and are consistent with the ratio $g_1^d(x)/f_1^d(x)$. The asymmetries are parameterized taking into account possible contributions from different parton distribution functions and parton fragmentation functions depending on the transverse spin of quarks.They can be modulated (either/or/and) with $sin(phi), sin(2phi), sin(3phi)$ and $cos(phi)$. The $x$-, $z$- and $p_h^T$-dependencies of these amplitudes are studied.

Perturbative QCD of hard and soft processes

We discuss some problems concerning the application of perturbative QCD to high energy processes. In particular for hard processes, we analyze higher order and higher twist corrections. It is argued that these effects are of great importance for understanding the behaviour of pion electromagnetic form factor at moderately large momentum transfers. For soft processes, we show that summing the contributions of the lowest twist operators leads to a Regge-like amplitude.