Department of Particle Physics and Astrophysics

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Uri Karshon

Professor Emeritus
Location:Edna and K.B. Weissman Building of Physical Sciences, Room 332

Current Research Interests

  1. Heavy quark production at the HERA e-p collider
  2. Gluon density in the proton and partonic structure of the photon
  3. Tests of QCD dynamics in high energy e-p collisions

Production of heavy quarks in high energy collisions between the basic constituents of the atom - the electron and the proton is being studied at the large HERA accelerator located at the DESY laboratory in Hamburg, Germany. The accelerator runs underground over a circumference of 6.3km. The study is performed with data taken at the ZEUS detector, which is a large set of various detector elements with an overall dimension of ~18x10x10m. The experiment is performed by the ZEUS Collaboration, which includes over 400 physicists from 52 institutions and 12 countries.

Many investigations have demonstrated that the proton is composed of partons (quarks and  gluons) and that gluons carry about half the energy of the proton. Out of the six types of known quarks, three (charm, beauty and top) are heavy. By studying the production of pairs of the heavy quarks charm and beauty in electron-proton collisions at HERA, one can infer the density of the gluons within the proton. This knowledge will yield a better understanding of the strong force between the partons within the proton.

The interaction between the electron and proton takes place by exchanging a particle that is responsible for the electric force - the photon. Heavy quarks can be produced in electron-proton collisions also via a process where the basic interaction is between a parton in the proton and a parton in the photon. The study of such processes will shed light on the partonic structure of the photon.

The above study will add valuable information on the contribution of charm and beauty to high energy scattering of electrons on protons and provide accurate tests on the predictions of the theory of the strong force, QCD, in a new regime which has never been explored before.