Thesis topics in Physics (for October 2022)

  1. Search for new physics with tau leptons and muons with the CMS experiment at LHC
    • Supervisor: Dr hab. Michał Bluj, prof. NCBJ
    • Description: The scientific goal of this doctoral project is to search for phenomena beyond the Standard Model (BSM) of elementary particles in final states with pairs of tau leptons and muons. The search will be conducted using data from proton-proton (pp) collisions at 13.5TeV, which will be collected by the Compact Muon Solenoid (CMS) experiment at CERN during the Run-3 of the LHC collider (2022-2024). The study will focus on the search for non-standard signatures including tau leptons and muons produced far from the pp collision vertex, so-called displaced tau leptons and muons. Such final states may arise from the decay of the hypothetical long-lived particles (LLPs) predicted by a number of extensions of the Standard Model. To date, a number of searches for long-lived particles have been performed, some with the CMS detector, but one of the still unexplored signatures are the final states with displaced tau leptons. Among models where such signatures are expected are those in which the LLP couples to particles of the Standard Model by mixing with the Higgs boson, or in which the LLP is a heavy neutral lepton, i.e. a heavy neutrino. The results of the search proposed in the Project may significantly contribute to setting strict limits to the proposed BSM scenarios or to the discovery of new particles. The first stage of the planned research is to develop algorithms for the reconstruction of the signal characteristic for hadronic decays of tau leptons produced outside the interaction point as such algorithms are currently not available in the CMS experiment. The next step is to construct the analysis, i.e. define the event selection, background estimation methods and statistical analysis of the results.
    • Funding: NCBJ Fellowship
  2. Study of the unbound nucleus 10Li via the 9Li(d,p)10Li stripping reaction
    • Supervisor: Dr hab. Nicholas Keeley, prof. NCBJ
    • Description: The unbound nucleus 10Li exists as a resonance in the 9Li + n system and in addition to its intrinsic interest it is also important as a sub-system of the weakly-bound Borromean nucleus 11Li. Within this context an accurate evaluation of the spectroscopic factor for the <10Li | 9Li + n> overlap is crucial. While spectroscopic factors are not observables they can be obtained from direct reaction data via the application of a suitable model of the reaction, and although the resulting values will necessarily be to some extent model dependent, with careful analysis and a complete data set of reasonable quality it should be possible to extract an absolute spectroscopic factor with an uncertainty of the order of 20- 30%. The object of this proposal is to obtain data for the 9Li(d,p)10Li reaction, performed in inverse kinematics (i.e. with a beam of radioactive 9Li nuclei incident on a deuterium-rich target), together with the corresponding elastic and inelastic scattering data to enable the extraction of the spectroscopic factor for the <10Li | 9Li + n> overlap under the best possible conditions. Ideally the complete data set would be obtained in a single experiment at a radioactive beam facility such as GANIL, France, SPES, Italy or TRIUMF, Canada at an incident energy of 10-20 MeV/nucleon. Previous measurements of this reaction have been made [1-3] but suffer from poor statistics and/or a limited angular range. The aim of this proposal would be considerably to improve on the quality of these data while at the same time enabling the entrance channel distorted waves – an essential part of the analysis required to extract the spectroscopic factor – to be fixed using the simultaneously measured elastic scattering. The successful candidate will be expected to participate in the setting up and carrying out of the experiment and to carry out the data reduction procedures in addition to performing the reaction analysis to extract the spectroscopic factor. Full training in these aspects will be given.
      [1] H. B. Jeppesen et al., Nucl. Phys. A 748, 374 (2005).
      [2] H. B. Jeppesen et al., Phys. Lett. B 642, 449 (20060.
      [3] M. Cavallaro et al., Phys. Rev. Lett. 118, 012701 (2017).
    • Funding: NCBJ Fellowship
  3. Quantum groups from quantum gravity
    • Supervisor: prof. dr hab. Jerzy Kowalski-Glikman
    • Description: The quest for quantum gravity is one of the most important unfinished challenges of modern high energy theoretical physics. Its solution will presumably provide us, among others, with an understanding of very early stages of the evolution of the universe and physics of black holes. Unfortunately, in the construction of this theory we not only encounter enormous technical problems, but also, we seem to be guided by only few experimental hints. This is due to the fact that the energy scale where quantum gravity effects become dominant is about 15 orders of magnitude higher that the highest energies seen at LHC. It is of major importance therefore to investigate possible traces that quantum gravity generically leaves at lower energies, changing slightly the theories that we know well and for which we can try to experimentally observe minute departures from the expected behavior. For example, the influence of quantum gravity may modify the early universe cosmological scenarios and the theory of quantum fields, used in the construction of the Standard Model of elementary particle physics. One of the possible ways to organize these possible quantum gravity corrections is to take as a starting point the hypothesis that they are captured by a subtle modification of our low energy theories associated with the emergence of quantum groups that become necessary to properly describe the spacetime symmetries. The aim of the research project the PhD student is supposed to undertake would be to to find out how quantum groups emerge as an effective description of symmetries of fields and particles when quantum gravity effects are considered. Literature: J.Kowalski-Glikman, “A short introduction to kappa-deformation”, Int. J. Mod. Phys. A 32 (2017) no.35, 1730026, doi:10.1142/S0217751X17300265 [arXiv:1711.00665 [hep-th]].
    • NCBJ Fellowship
  4. Cosmic evolution of galaxy dust properties within the cosmic web
    • Supervisor: Dr hab. Katarzyna Małek, prof. NCBJ
    • Auxiliary Supervisor: Dr Darko Donevski
    • Description: Recent advent in infrared and submillimetre astronomy established an important role of dust in understanding the galaxy evolution. The existence of dust in galaxies affects the galaxy physics, the chemical evolution of matter, star-formation and the absorption and re-emission of stellar light. The last years have seen a surge in observational and theoretical studies constraining the dust-abundance of galaxies up to very high redshifts (z~5). These studies opened an important question on role of large- scale environments on the life cycle of dust in galaxies. The proposed PhD project Cosmic evolution of galaxy dust properties within the cosmic web aims at understanding the effect of cosmic web on the evolution of dusty galaxies, from the early Universe to the present time. Successful candidate will study this topic by analysing unique statistical sample of observational data and state-of-the-art simulations. The project intends to provide the solid ground needed for interpreting future unprecedented data sets of galaxies in the distant Universe observed with ground-based submillimetre instruments (i.e., NOEMA, ALMA, JCMT) and space telescopes (i.e., JWST).
    • Funding: NCN Fellowship
  5. Novel ways to study the nature of particle dark matter
    • Supervisor: Prof. dr hab. Leszek Roszkowski
    • Auxiliary Supervisor: Dr Sebastian Trojanowski
    • Description: The search for dark matter (DM) remains one of the most puzzling topics in contemporary physics. While DM has been found to correspond to a large fraction of the total energy budget of the Universe, its particle nature remains unknown. It avoids detection despite strong experimental efforts, while further such searches will deliver data in the near future. The last several years have led to an important paradigm shift in these studies. The increasing popularity of light or ultra-light DM species, i.e. with the mass (much) below the proton mass, has motivated new theoretical ideas which are currently shaping future experimental programs in the biggest laboratories all over the world. This PhD project will focus precisely on such new ideas and their phenomenological implications. The successful candidate will perform a comprehensive analysis of various possible theoretical models of DM interactions focusing on scenarios with poor detection prospects in current searches which could be better probed in the relativistic regime, in astrophysical phenomena, or by taking into account cosmological constraints. While the PhD program will focus on theoretical studies, the research conducted by the PhD student will also inform the decision process with regard to future experimental proposals. To this end, an emphasis will be put on a novel physics program in the far-forward region of the Large Hadron Collider (LHC), which is soon to be initiated by the FASER experiment. We seek strongly motivated candidates interested in particle and astroparticle physics who will work on their thesis within the Particle Physics group at NCBJ, while will also be open to frequent international collaborations.
    • Funding: NCN Fellowship
  6. Dark matter and baryogenesis within multicomponent dark sectors
    • Supervisor: Dr hab. Enrico Maria Sessolo, prof. NCBJ
    • Auxiliary Supervisor: Dr Andrzej Hryczuk
    • Description: The proposed topic is a theoretical study of non-minimal dark sectors in the very Early Universe with the emphasis on interconnections between dark matter production, reheating and baryogenesis. The project will explore these possible connections with the new addition of studying the evolution of the dark matter component at the level of its phase space distribution function, and not rely on the limit of fluid description. Successful candidate will have an opportunity to learn state-of-the-art approaches to study the dark matter production and beyond, and contribute to the research in this timely topic. The project will combine pen and paper calculations, with numerical computations and code development.
    • Funding: NCN Fellowship
  7. Vector boson physics with the CMS experiment at the Large Hadron Collider
    • Supervisor: Dr hab. Michał Szleper, prof. NCBJ
    • Description: Vector Boson Scattering (VBS) is a wide class of processes of paramount importance for the proper understanding of the mechanism of electroweak symmetry breaking. They probe Higgs couplings as well as triple and quartic gauge couplings, and thus are indirect checks for physics beyond the Standard Model. We look for two strong candidates who would like to work with the CMS experiment at CERN as part of their Ph.D. program. The successful candidates are expected to participate in the analysis of VBS processes based on data that will be collected during Run 3 of the LHC. The main focus of the analysis will be search for new physics in the same-sign WW scattering process and the WZ scattering process using the model independent framework of Effective Field Theories. Prerequisits are a M.Sc. degree in particle physics or a closely related field, good computing skills and ability to establish a friendly collaboration with the international scientific community at CERN. Good understanding of particle physics theory will be a bonus. The successful candidates are also expected to participate in activities related to the maintenance and operation of the Overlap Muon Track Finder (OMTF) system of the CMS detector, as part of their service work within the Warsaw CMS group.
    • Funding: NCN Fellowship
  8. Determination of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment
    • Supervisor: Prof. dr hab. Wojciech Wiślicki
    • Co-supervisor: Prof. dr hab. Andrzej Kupść
    • Description: The muon anomalous magnetic moment g-2, where g is the gyromagnetic ratio of the muon, is one of the exceptional cases in particle physics at low energy where a significant discrepancy between measurement and Standard Model (SM) prediction has persisted for more than 20 years. This discrepancy, now reaching 4.2 sigma, could be a compelling evidence of physics beyond the SM. In view of the new experimental efforts under way at Fermilab (USA) and J-PARC (Japan) to improve the g-2 accuracy, a confirmation of its SM prediction is now mandatory. Its hadronic contributions are under particular scrutiny, as they induce the main uncertainty of the SM prediction. The KLOE experiment at the phi-factory DAphNE in Frascati (near Rome) is the first to have employed Initial State Radiation to precisely determine the e+e- –> pi+pi-gamma cross section below 1 GeV. This PhD project is focused on the analysis of the full KLOE data sample and should improve by a factor 2 current accuracy on contribution to g-2 from hadronic vacuum polarization. It will place a significant constraint on the SM prediction to the muon g-2. The project also requires involvement in development of Monte Carlo generator for this process. A successful candidate is expected to work on the analysis of data and simulation software and will be assisted by experienced senior colleagues.
    • Funding: NCBJ Fellowship