Experimental Tests of the Fundamentals of QCD

Participating countries and international organizations:

Belarus, CERN, China, Czech Republic, Germany, Israel, Italy, Japan, Poland, Portugal, Russia, United Kingdom, USA.

The problem under study and the main purpose of the research:

Quantum chromodynamics is a true theory of strong interaction. However, despite its considerable success in describing the interaction of quarks and gluons within the perturbative approach, the question of why hadrons and nuclei are as we see them remains open. Description of fundamental properties of hadrons, such as their masses, spins, parton distributions, form factors, spectra, etc., on the basis of basic principles of QCD is one of the main unsolved problems of quantum chromodynamics. Confinement of quarks and gluons in hadrons, as well as the growth of the running constant of strong interaction with decreasing characteristic scale of interaction energy does not allow direct use of the perturbative approach, which has proved itself at high energies. At present, various phenomenological models are used to quantitatively describe the hadron spectrum, their static properties, and their interactions at low energies. Certain success has been achieved in lattice calculations. A comparison of model predictions and theoretical calculations for observables with measurement results is an important test of the consistency and applicability limits of the approaches used. The ultimate goal of research in this direction, both theoretical and experimental, is to obtain a description of the spectra, structure, and properties of hadrons from first principles of QCD.

Brief annotation and scientific rationale:

The goals of the JINR group in the BESIII project are to study hadronic QCD spectra and search for exotic states, study the production and decays of Charmonium states, search for exotic Charmonium states and charmonium-like structures, and determine c-quark fragmentation functions. The JINR group's participation in the project consists of data analysis and development of algorithms for event reconstruction in the BESIII detector using machine learning methods. 

Expected results upon completion of the project:

The project will produce new knowledge about the properties of strong interactions on the Q²~ M²_Jpsi scale. In particular, information will be obtained on the spectrum of exotic light and charmonium-like states and their properties, as well as on the details of inclusive c-quark production.

Expected results of the project in the current year:

1. BESIII data analysis.

2. Development of offline software and analysis tools.

3. Participation in the data taking.

Brief annotation and scientific rationale:

AMBER (Apparatus for Meson and Baryon Experimental Research) is a new experimental facility with a fixed target on the M2 beam line of the CERN SPS. The facility is designed to perform a variety of measurements aimed at addressing fundamental questions of quantum chromodynamics, which are expected to lead to a significant improvement in the understanding of QCD as a modern theory of strong interactions. The proposed measurements cover physics ranging from the smallest Q² values, such as determining the charge radius of a proton in elastic muon-proton scattering, reactions with mean Q² values for hadronic spectroscopy, and z studies of hadronic structure with high Q² using rigid Drell-Yan, Charmonium, and fast photon production processes. The JINR group is responsible for the modernization and operation of the HCAL1 hadron calorimeter and the MW1 (Muon Wall 1) high-angle muon identification system. It is also involved, along with a group from the University of Turin, in the production and support of the Bulk Micromegas track detectors that will replace the obsolete multi-wire chambers (MWPCs) in the SAS behind the SM2 magnet.

Expected results upon completion of the project:

Solving the proton radius puzzle. New knowledge of the quark and gluon structure of mesons.  Accurate knowledge of the yield of antiprotons in p-p and p-He processes, essential for the search for dark matter in astrophysical experiments.

Expected results of the project in the current year:

1. Participation in the data taking for the Proton Radius Measurement program.

2. Participation in R&D for Micromegas detectors.

3. Preparation of the front-end electronics upgrade to be able to operate in the triggerless mode.

 Collaboration

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