Fyzikální ústav Akademie věd ČR

String theory is the only known theory that consistently unifies all four fundamental interactions: the electromagnetic, gravitational and strong and weak nuclear forces. Its consistency with quantum mechanics makes it also the leading candidate for quantum gravity theory. String theory faces two major challenges which might be related to each other: it can allow our universe to have too many distinct physical properties (such as the masses and coupling constants of elementary particles) and therefore lack of clear experimental predictions. The second major challenge is a lack of proper non-perturbative formulation which would define the theory also in the regime of extreme quantum behavior such as at the beginning of our universe or deep within black holes.

An important problem of perturbative QCD is an accurate determination of the strong coupling α_s from hadronic τ decays. The decay width R_τ can be determined from the two-point correlation functions Π(s) which are the Fourier transforms of vacuum expectation values of current products.   The full text >>

For more than 10 years we are participating in the DZero experiment which detects and analyzes the results of the proton-antiproton interactions provided by Tevatron collider in Fermilab. We are focusing on jets - collimated sprays of particles which are fingerprints of violently scattered proton constituents, quarks   The full text >>

Study of heavy ion collisions at ultra high energies represents a hot issue in the contemporary nuclear and particle physics. A fundamental motivation for this study is to verify the prediction of the current theory of the strong interaction (called Quantum Chromo-Dynamics), which implies that at very high temperatures and very high densities of the nuclear matter, quarks and gluons should no longer be confined inside composite particles. Instead they should exist freely in a new state of matter known as quark-gluon plasma (QGP).  The full text >>