BP2 achievements 2013-16: Theoretical studies on scattering of medium- and high-energy elementary particles

Effects of de-correlation in production of jets have been analysed with the help of some advanced theoretical methods of quantum chromodynamics. All known facts concerning theoretical description of that process have been taken for the first time into account. The results are quite spectacular: first of all they are in line with data supplied by the CMS collaboration working at LHC, secondly they may help to postulate in the future measurements of some new properties. Additionally, optimum re-normalization scale responsible for the value of strong coupling constant have been calculated. The results are available in a series of papers published by several recognized journals [1]. Other important results include (i) a proposition of a new jet production mechanism based on double distributions of partons and (ii) evaluation of its contribution. Such distributions appear if two jets are produced independently. The results has confirmed reliability of theoretical predictions concerning jet production.

The developed in NCBJ method was next applied for the first time to take radiative corrections into account; the results have been published in a series of papers [2]. The objective was to describe some selected phenomenological processes of exclusive diffractive production of two and three jets; such production is extremely important from experimental point of view. Such production of jets is currently studied in HERA, similar experiments are planned in LHC and in (future) Electron Ion Collider. A formula to calculate cross sections for similar processes have been elaborated just for that reason. It must be pointed out that the elaborated formula is free from infrared divergence and rapidity problems. The result is a starting point to subsequent works on quantitative predictions which could be compared with experimental data.

A great deal of attention was also paid to various properties of hadrons discovered in hard exclusive processes, including time-like Compton scattering, photo-production of charmonium, production of charm mesons in neutrino-nucleon collisions. The obtained spectacular results have been published in excellent journals (Phys. Rev. Lett, J. High Energy Phys, Phys. Rev. D). In spite of some earlier expectations, a large contribution of gluons to cross section was shown. That raises a question of possible experiments aimed to measure their distributions (possible e.g. in Jefferson Lab in the USA). It was also shown how experiments with neutrinos may be used to reveal properties of transversity of quarks in nucleons. That topic is usually beyond experimental verification.

[1] B. Ducloue, L. Szymanowski, S. Wallon, J. High Energy Physics 1305 (2013) 096, Phys. Rev. Lett. 112 (2014) 082003, Phys. Lett. B738 (2014) 311, Phys. Rev. D 92 (2015) 7, 076002 , A.H. Mueller, L. Szymanowski, S. Wallon, B.W. Xiao, F. Yuan, J. High Energy Physics 1603 (2016) 096
[2] R. Boussarie, A.V. Grabovsky, L. Szymanowski and S. Wallon, J. High Energy Physics 09 (2014) 026, ibid 11 (2016) 149,
[3] H. Moutarde, B. Pire, F. Sabatie, L. Szymanowski, J. Wagner, Phys. Rev. D 87 (2013) 054029, Few Body Syst 55 (2014) 339; B. Pire and L. Szymanowski, Phys. Rev. Lett. 115 (2015) 092001; J.P. Lansberg, L. Szymanowski and J. Wagner, J. High Energy Phys. 09 (2015) 087; J. Wagner, L. Szymanowski, B. Pire and D.Yu. Ivanov, AIP Conf. Proc. 1654 (2015) 090003