Theoretical investigations in BP2 of collisions of leptons/hadrons/nuclei
last updated : December 2014
- Explanation of logarithmically periodic oscillations (LPO) in distributions of transversal momenta (pT ) observed in LHC experiments at large values of pT .
- Understanding the structure of hadrons – strongly interacting particles composed of quarks and gluons – within framework of the currently accepted model of strong interactions (quantum chromodynamics).
- Exclusive processes of elementary particle production within framework of quantum chromodynamics co-linear factorisation and Regge factorisation in parton transversal momenta.
- Analysis of multi-particle production processes in high-energy collisions of hadrons and nuclei.
- Nucleon structure spin functions and spin-dependent effects in collisions of hadrons/leptons.
WORKS PERFORMED IN 2014
- Phenomenological predictions for experiments in which exclusive particle production is observed.
- Results indicating that distributions of transversal momenta in pp/AA collisions scale up with energy.
- Review of mechanisms responsible for distribution of momenta of particles produced at high energy collisions.
- Two possible approaches based on description of the above distributions by non-extensive Tsallis formulae with the T scale parameter (“temperature”) and the q non-extensivity parameter were proposed: (i) use compound values of the q parameters  at fixed T; (ii) use real values of the q parameter and introduce LPOs for T .
- Analysis of COMPASS experiment data on polarisation of gluons was finalized. The NLO QCD approximation was used. Such results were published for the first time in the world. A neuron-network-based method employing statistical weighing was developed to analyse the Sivers effect for gluons. Preliminary results for Sivers asymmetry in photon-gluon fusion processes on deuterium target.
THE MOST ESSENTIAL ACHIEVEMENTS (2014)
- It was pointed out that the LPO oscillations appear naturally in strictly exponential scalable distributions (invariable to scale changes). A variable in which the distribution exhibits scalability and may have LPOs was found. It turned out that LPOs were present also in nuclei collisions and that they grow with decreasing the collision central character.
- Results on gluon polarisation in the NLO QCD approximation were published. Method to analyse Sivers asymmetry in COMPASS experiment data on gluons was worked.
APPLICABILITY OF THE OBTAINED RESULTS
- Szymanowski and Wagner – co-authors of “Letter of Intent” submitted to Thomas Jefferson National Accelerator Facility.
- Predictions for LHC experiments and search for dark matter.
- It was shown that only the lightest Higgs bosons among the three bosons possible according to the Constrained NMSSM model was compatible with the newly discovered particle.
- The results will be applied to analyse data obtained in the Jlab and Compass experiments, and to more accurately reveal generalized distributions of partons (strong interactions coupling constant higher order terms taken into account ).
- Published asymmetries in the D meson production (open-charm, the channel that makes possible to interpret asymmetry from polarisation of gluons on target nuclei) will be used to analyse the so-called QCD global fit –– a basic tool to determine polarised distributions of quarks and gluons in a nucleon. The global fit employs all data available from various type experiments and is performed by several independent teams of theoreticians.
- The developed method of analysis of Sivers effect for gluons on the basis of COMPASS experiment data acquired on a transversally polarised target will be applied to determine Sivers asymmetry for gluons on deuteron and proton.
- Comparison of the results should answer the questions on orbital momentum and on deformation of the transversal distribution of gluons in nucleon i.e. the question of distribution of “colour” within nucleon.
- Professor Grzegorz Wilk
- Assistant Professor Lech Szymanowski
- Assistant Professor Krzysztof Kurek
- Dr. Jakub Wagner
This page edited by:Marek Pawłowski