Spontaneous breaking of parity or time reversal invariance offers a solution to the strong CP problem, the stability of which under quantum gravitational effects provides an upper limit on the scale of symmetry breaking. Even more important, these Planck scale effects may provide a simple and natural way out of the resulting domain wall problem. ∗Invited talk at the 4th Hellenic School on Eleme...

Giant resonances are collective excitation modes for many-body systems of fermions governed by a mean field, such as the atomic nuclei. The microscopic origin of such modes is the coherence among elementary particle-hole excitations, where a particle is promoted from an occupied state below the Fermi level (hole) to an empty one above the Fermi level (particle). The same coherence is also predi...

As argued in our previous papers, it would be more natural to modify the standard approach to quantum theory by requiring that i) one unitary irreducible representation (UIR) of the symmetry algebra should describe a particle and its antiparticle simultaneously. This would automatically explain the existence of antiparticles and show that a particle and its antiparticle are different states of ...

A non-associative algebraic construction is introduced vbich "bears a relation to a Lie algebra SL paralleling the relation between an associative enveloping algebra and oC , The key ingredient of this algebraic construction is the presence of two parameters which relate it to the enveloping algebra of jf . The analogue of the Poincare-Birkhoff-Witt theorem is proved for the new algebra. Possib...

Physikalisches Institut, Albert-Ludwig-Universität Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg Abstract.The Standard Model of elementary particles is remarkably succesful in describing experimental data. The Higgs mechanism as the origin of electroweak symmetry breaking and mass generation, however, has not yet been confirmed experimentally. The search for the Higgs boson is thus one of t...

In order to extend the Standard Model to TeV scale energies one must address two basic questions: (1) What is the complete description of the effective theory of fundamental particles at and below the electroweak scale? and (2) What is the dynamics responsible for electroweak symmetry breaking? The answers to these questions are crucial for addressing the third outstanding question of particle ...

Title of dissertation: A SUSY SO(10) GUT MODEL WITH LOPSIDED STRUCTURE Yingchuan Li, Doctor of Philosophy, 2007 Dissertation directed by: Professor Xiangdong Ji Department of Physics The standard model (SM) of elementary particles has been established for more than 30 years and tested by a large number of experiments. However, because of the naturalness problem of the electroweak symmetry break...

High-precision measurements of violations of fundamental symmetries in atoms are a very effective means of testing the standard model of elementary particles and searching for new physics beyond it. Such studies complement measurements at high energies. We review the recent progress in atomic parity nonconservation and atomic electric dipole moments (time reversal symmetry violation), with a pa...

Hyperons have been among the first non-stable elementary particles discovered and are known for more than 50 years now. In spite of this, the physics interest in hyperons is by far not yet exhausted, several important aspects are still under intense investigation. At first, as hyperons only differ by one or two strange-quarks from proton and neutron, they are ideal playgrounds to study SU(3)f s...