Produkce pionů, kaonů a protonů identifikovaných detektorem RICH v DIS na experimentu COMPASS
| Thesis title in Czech: | Produkce pionů, kaonů a protonů identifikovaných detektorem RICH v DIS na experimentu COMPASS |
|---|---|
| Thesis title in English: | Production of pions, kaons and protons identified by a RICH detector in DIS at COMPASS experiment |
| Key words: | DIS|SIDIS|COMPASS|TMD PDF|RICH|struktura nukleonu |
| English key words: | DIS|SIDIS|COMPASS|TMD PDF|RICH|nucleon structure |
| Academic year of topic announcement: | 2024/2025 |
| Thesis type: | dissertation |
| Thesis language: | |
| Department: | Department of Low Temperature Physics (32-KFNT) |
| Supervisor: | Mgr. Jan Matoušek, Ph.D. |
| Author: | hidden - assigned and confirmed by the Study Dept. |
| Date of registration: | 02.10.2024 |
| Date of assignment: | 02.10.2024 |
| Confirmed by Study dept. on: | 02.10.2024 |
| Guidelines |
| - Get familiar with the COMPASS experiment and its ring-imaging Cherenkov (RICH) detector. Learn the data processing routines used at COMPASS.
- Evaluate and try to optimize the efficiency and purity of the RICH detector of COMPASS in hadron identification (using decays of rho, phi, and lambda particles). - Study the possibility to use calorimetry to suppress electrons and positrons in the hadron sample. - Study the distributions of identified hadrons in deep-inelastic scattering (DIS). Measure the multiplicity as a function of the transverse momentum as well as the azimuthal distribution of the hadrons. - Interpret the results in terms of transverse-momentum dependent PDFs and fragmentation functions. |
| References |
| - COMPASS Collaboration: The Compass Experiment at CERN, Nucl. Instr. Meth. 577, 2007, http://arxiv.org/abs/hep-ex/0703049.
- COMPASS Collaboration: Measurement of azimuthal hadron asymmetries in semi-inclusive deep inelastic scattering off unpolarised nucleons, Nucl. Phys. B 886, 2014, http://arxiv.org/abs/arXiv:1401.6284 - COMPASS Collaboration, Collins and Sivers asymmetries in muonproduction of pions and kaons off transversely polarised proton, Phys. Lett. B 744, 2015, http://arxiv.org/abs/arXiv:1408.4405 - COMPASS Collaboration: Transverse-momentum-dependent multiplicities of charged hadrons in muon-deuteron deep inelastic scattering, Phys. Rev. D 97, 2018, http://arxiv.org/abs/1709.07374 - C. Chatterjee, Performance study of the RICH at COMPASS experiment for hadron identification in SIDIS physics, University of Trieste, 2020, https://wwwcompass.cern.ch/compass/publications/theses/2020_phd_chatterjee.pdf - A. Moretti: Study of the Transverse-Momentum-Dependent structure of the nucleon in Semi-Inclusive DIS, PhD thesis, University of Trieste, 2021, https://wwwcompass.cern.ch/compass/publications/theses/2021_phd_moretti.pdf - PHAST: PHysics Analysis Software Tools. http://ges.web.cern.ch/ges/phast/index.html. - ROOT data analysis framework. https://root.cern.ch/. |
| Preliminary scope of work in English |
| The structure of hadrons is encoded in the equations of QCD. However, fifty years after the discovery of quarks the theoretical calculations are just beginning to realistically describe their arrangement in hadrons. The COMPASS collaboration collected data on semi-inclusive deep-inelastic scattering of muons off hydrogen and off
transversely polarised protons and deuterons. Hadrons produced in this process carry the information on the intrinsic transverse momentum and on the polarisation of quarks of different flavours – a 3D mapping of the nucleon in the momentum space. In the context of high-energy particle collisions the hadron structure is described by transverse momentum dependent parton distribution functions (TMD PDFs). They are functions of the longitudinal momentum fraction x carried by a particular parton and of the intrinsic transverse momentum k_T squared of the parton. They encode all possible correlations between the nucleon spin,the parton spin and k_T. While the x-dependence is rather well known, accessing the distribution of k_T^2 is difficult, as it is not observable directly. Measuring transverse momentum P_T of hadrons produced in DIS, one accesses a convolution of the k_T of the struck quark and of the transverse momentum obtained in hadronisation. To disentangle the effects, one can use transverse-momentum-dependent multiplicities of hadrons produced in e+e− annihilation, which were recently published [Belle, Phys.Rev.D99 (2019) 112006]. Another way to access the intrinsic k_T is via the Cahn effect – a modulation in the azimuthal angle phi_h of hadrons produced in DIS. However, the available COMPASS and HERMES results point to much smaller values of k_T than those coming from the measurements of P_T [Barone et al., Phys.Rev.D91 (2015) 074019]. To understand the complicated picture, it is desirable to carry out a fully multi-dimensional measurement for identified hadron species (pi, K, p). One can also study the possibility to measure neutral pions and kaons and vector mesons such as rho. The large data sample collected by COMPASS in 2016-2017 on liquid hydrogen target allows such a measurement. The data collected in 2022 on polarised deuterium give in addition access to spin-dependent TMD PDFs, such as the polarisation of quarks in a transversely polarised nucleon (so-called transversity PDF) and the correlation between quark transverse momentum and nucleon transverse polarisation (Sivers TMD PDF). The study may be conducted in cooperation with University of Trieste in the framework of a 'cotutelle' agreement. |