Dissertation for the Degree of Doctor of Philosophy in high energy physics presented at Uppsala University in 1996
Thunman M. 1996. Studies of High Energy Leptons in Astroparticle and Charm Quark Physics. Acta Universitatis Upsaliensis, Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 210. 48 pp. Uppsala. ISBN 91-554-3766-4.
Cosmic-ray physics was an important source of knowledge in the early days of particle physics with, e.g., some important elementary particle discoveries. The field is now regaining interest due to its connection to astroparticle physics and new types of experiments such as large neutrino telescopes for high energy neutrino astronomy. The neutrinos could come from many different sources of interest for astrophysics and particle physics; e.g. active galactic nuclei and annihilation of supersymmetric dark matter.
Cosmic-ray interactions are investigated using models for high energy particle physics collisions. In particular, Monte Carlo methods are used to simulate primary interactions, emerging particles and secondary cascading interactions.
Cosmic-ray interactions in the interstellar medium of the Milky Way and a possible baryonic dark matter halo are investigated, as well as interactions in the Sun's atmosphere with a possibility to use the Sun as a `standard candle' for neutrino telescopes or to search for neutrino oscillations. The fluxes of muons and neutrinos from cosmic-ray interactions in the Earth's atmosphere are calculated in the energy range 102-108GeV . Special attention is here given to charm particle production and decay, which is investigated using both perturbative QCD and the intrinsic charm hypothesis. The fluxes obtained from all these processes are interesting per se and as a background to other astroparticle physics sources.
The possibility to confirm the hypothesis of `intrinsic' charm quark-antiquark pairs in the proton wave function through possible signals in high energy particle collisions is investigated. Detailed models for both lepton-proton scattering and hadronic collisions are constructed and used to calculate differential charm particle production cross sections. These are compared with conventional charm production in perturbative QCD and available data. A possibly over-looked signal in available data is pointed out and predictions are made for the Tevatron and LHC colliders.
Mats Thunman, Department of Radiation Sciences,
Uppsala University,
Box 535, S-75121 Uppsala, Sweden.
© Mats Thunman 1996
ISSN 1104-232X
ISBN 91-554-3766-4
Printed in Sweden by Graphic Systems, Stockholm, 1996