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DEPARTMENT OF ELEMENTARY PARTICLE
PHYSICS

Theoretical Particle Physics

The Standard Model of particle physics seems presently to be at the height of its success. No signals of new were so far found neither in electroweak precision tests nor in flavor physics studies. However, in spite of remarkable success, there are profound experimental and theoretical reasons to think that the Standard Model is incomplete. They include the gauge hierarchy problem, family regularities in the observed spectrum of quarks and leptons which are slightly smeared by their weak (CP-violating in general) mixing, tiny (but non-vanishing) neutrino masses and others, as well as the very fact that the Standard Model does not yet incorporate the gravity which seems to be a basic drive for a present development in particle physics and cosmology.
A possible intermediate solution to these problems is commonly related to supersymmetry, supergravity and grand unified theories, enlarged enough to include also some family symmetries treating quark-lepton generations. At present they receive some indirect experimental support from the apparent lightness of the Higgs boson, the values of the electroweak and strong interaction gauge couplings given by precision measurements, the heavy top quark mass, and an experimental evidence for non-zero neutrino masses which could explain (via their oscillations) the persistent atmospheric and solar neutrino deficit.
As to the final solution, it is widely believed that the known four fundamental forces which govern all physical phenomena observed have a common origin in terms of the ultimate superstring theory in which gravitation appears unified with the strong and electroweak forces through extra space-time dimensions involved. While usually this unification is proposed to be in the range of ~ 1016 to ~ 1018 GeV, the possibility of unification at much lower energies is also existed if extra dimensions properly appear at larger distances. However, any persuasive link between present string theory and the SM physics with all particular features observed at low energies is rather difficult to be established. Any particular superstring theory set-up usually appears too restrictive to cover the existing realistic models in a valuable phenomenological way.
this respect, the "bottom-up" approach starting with an effective quantum field theory framework for elementary quarks and leptons, both standard and supersymmetric, which we follow in a systematic way, looks more promising since it might provide guiding rules for search for new physical phenomena, as well as could shed light on the underlying string dynamics towards the final theory of matter. One of the most interesting examples of this type could be an origin of internal symmetry patterns in particle physics owing to spacetime instabilities (spontaneous Lorentz violation) at very small distances leading to realistic schemes for unified theories of quarks and leptons.
Present research interests of the Department are focused to physics beyond the Standard Model: grand unified theories and supersymmetry, spontaneous Lorentz violation and origin of symmetries, emergent QED and Gravity theories, extra spacetime dimensions in particle physics and cosmology. Special line in the research program is related to supersymmetric grand unification and proton decay, the problems of quark-lepton flavor mixing and CP violation, model building for neutrino oscillations and others. One of the main concerns of the group members is in sharpening of their ideas for their phenomenological applications at facilities, such as the large hadron collider (LHC) and underground detectors.