Univerzalnost leptonskega okusa

Standardni model je teorija, katere napovedi o interakcijah med osnovnimi delci se odlično ujemajo z meritvami, a ima tudi svoje pomanjkljivosti. Dopolnitve teorije ali nove teorije, ki presegajo Standardni model, imenujemo s skupnim imenom Nova fizika. Eden od pristopov iskanja Nove fizike je preko preverjanja univerzalnosti leptonskega okusa, saj po Standardnem modelu vsi leptoni preko šibke interakcije nastopajo na enak način, z enako sklopitveno konstanto GF. Univerzalnost leptonskega okusa se preverja na eksperimentih Belle II in ATLAS, kjer se iz podatkov pridobljenih v detektorju, izlušči potrebne informacije s pomočjo postopka rekonstrukcije. Novo fiziko se išče preko preverjanja različnih razvejitvenih razmerij. V članku so omenjena razmerja R(τ /μ), R (D) in R (D*), pri katerih so bila do zdaj izmerjena odstopanja od Standardnega modela. Odstopanje zaenkrat ni dovolj znatno, da bi lahko govorili o odkritju Nove fizike, obstajajo pa že teorije, ki ga razlagajo.

Lepton flavour universality

The Standard Model is a theory, whose predicted interactions between elementary particles match the experimental data very well, however it leaves some phenomena unexplained. New theories that explain deficiencies of the Standard Model are called New Physics. One of the approaches of finding New Physics is through testing the validity of lepton flavour universality, since according to the Standard Model, all leptons participate through weak interaction in the same way, with the same coupling constant GF. Lepton flavour universality is being tested at experiments Belle II and ATLAS, where necessary data is being extracted via reconstruction of an event from the data collected by a detector. New Physics can be found by measuring certain branching fractions, such as R(τ /μ), R (D) and R (D*), where a deviation from the Standard Model predictions has already been found. Although current measurements of deviation from the Standard Model predictions are not significant enough to talk about discovering New Physics, there already exist theories that explain it.