Nuclear
Physics Colloquium Nuclear
Physics ColloquiumVenue: Physics Building, Max-von-Laue-Str. 1, Seminar
Room PHYS 2.116
Time: Thursday, June 09, 4:30 pm (s.t.)
Contact: hees@fias.uni-frankfurt.de
Modern
hadron physics plays a vital role for two fundamental questions: 1. How
do the known elementary particles form the matter around us? 2. Is there
physics beyond the known elementary particles? Concerning the first
question, hadron physics studies how the quarks and gluons form hadrons.
Electromagnetic form factors encode an important part of this
information. Concerning the second question, hadron physics is needed to
provide reliable standard-model predictions for high-precision
quantities like the magnetic moment of the muon. Only then a possible
deviation between observation and standard-model prediction can point to
the influence of new physics instead of to the influence of
quantitatively not understood hadronic fluctuations. For the magnetic
moment of the muon electromagnetic transition form factors of mesons
play a decisive role to decrease the theoretical uncertainty of the
standard-model prediction.
The major
part of my talk will report about the ongoing work to calculate the pion
transition form factor in a model independent way and therefore with a
reliable estimate for the theoretical uncertainty. The final aim is to
qualitatively and quantitatively improve the standard-model prediction
for the gyromagnetic ratio of the muon.
The last
part of my talk will address form factors of hyperons. These siblings of
the nucleon will be copiously produced in proton-proton and
proton-antiproton collisions at FAIR and can be studied by HADES and
PANDA, respectively. The intrinsic structure of hyperons can be probed
in dilepton decays. It will be interesting to see how much alike or
different the intrinsic structure of hyperons is as compared to nucleons
and Deltas.
On the
technical side the presented calculations for both the pion and the
hyperons are based on dispersion theory and chiral perturbation theory.