Strange and charmed hyperon physics in electromagnetic and strong interaction

Tord Johansson, Nuclear Physics, was granted 3 million SEK for the project “Strange and charmed hyperon physics in electromagnetic and strong interaction” from the Swedish Research Council for the period 2017-2020.

Project description

Hadron Physics deals with one of the most challenging problems in contemporary physics, namely the understanding of the strong force that binds together the elementary constituents, quarks and gluons, into the observed particles (hadrons). At present, we do not know how to apply the theory of strong interaction, QCD, in the energy regime relevant to hadrons in which it displays many phenomena that remain to be understood. One prominent example is the permanent trapping of quarks inside the hadrons and the related question of the structure of these composite systems. To gain more insight one must perform experiments at an energy scale relevant to the hadron masses.

The Uppsala Experimental Hadron Physics group is involved in studies of the electromagnetic structure of hadrons at the BESIII experiment in Beijing, China, for which ground breaking results will be produced on hyperons. In particular, the study on the electromagnetic structure of the Λc will for the first time provide a complete set of observables. Furthermore, the first extraction of the moduli of the electric and magnetic form factors for the double strange Ξ hyperon will be made. This will allow for the first investigation of what happens to the electromagnetic structure of baryons when a light quark is replaced by a charmed quark or two light quarks are replaced by two strange quarks. The data has recently been collected with necessary statistics and will be analysed and published during the four-year period of this application.

Hyperon studies in antiproton-proton collisions are one of the pillars of the physics programme of the upcoming PANDA experiment at FAIR, Germany. It will be the first experiment to run with a free streaming, trigger-less data acquisition system. This, in combination with the displaced decay vertices from the hyperon decays, creates new and unique challenges for the collection and reconstruction of the data, especially at the high intensities that are to be expected at PANDA. We will develop necessary software tools for these projects. At the core is a reliable recognition of displaced decay vertices of the hyperons for both the on-line and off-line environment. In particular it should be capable to cope with the high event rates during on-line data taking and select such events. This is absolutely crucial to ensure the success of the hyperon programme with PANDA.

This application involves funding of personnel and travel grants to carry out these projects.