Seminář se koná každé úterý v 10:40 v posluchárně ÚTF MFF UK
v 10. patře katedrové budovy v Tróji, V Holešovičkách 2, Praha 8
Positrons — the antiparticles of electrons — appear in medical imaging (PET scans), materials diagnostics, astrophysics, and molecular spectroscopy, and are building blocks for exotic antimatter like positronium and antihydrogen, used to test fundamental symmetries of nature. When a low-energy positron encounters a molecule, the physics gets rich and subtle: the positron distorts the electron cloud, and a molecular electron can temporarily tunnel out to the positron — a process called virtual positronium formation. These many-body effects enhance annihilation rates by orders of magnitude and can allow the positron to bind to a neutral molecule. Getting the theory right is a genuinely hard computational problem, requiring strong electron-positron correlations to be accounted for from first principles. We tackle this using diagrammatic many-body theory, implemented in a parallelized C++ code, which has given the first ab initio predictions of positron-molecule binding energies in agreement with experiment, and enabled a framework that can treat positron scattering and annihilation on molecules with unprecedented accuracy.
Jiří Horáček David Heyrovský