The mediators of the weak force—the W and Z bosons—are both roughly 100 times more massive than the proton, while the photon, which mediates the electromagnetic force, is massless. Based on symmetry principles, one would have expected the W , Z, and photon (collectively called gauge bosons) to all be massless. In order to generate the required symmetry breaking, one must invent a particular set...

Understanding spontaneous symmetry breaking is essential to understanding characteristic phenomena of solid-state physics, condensed matter physics, elementary particle physics, and cosmology. I will forego the details of physical applications in order to concentrate on the implications of spontaneous symmetry breaking for general issues concerning laws and symmetries and for the foundations of...

16 WINTER 1999 YMMETRY IS A FAMILIAR CONCEPT in art and design. In daily conversation, it usually refers to transformations in space, such as rotations of an object about an axis. In science, the word has a more general meaning and a profound significance, because its role in understanding the laws of Nature has been one of the dominant themes in physics. It figured heavily, for example, in muc...

Symmetries, global or local, always play an important role in the conceptual aspects of physics be in broken or unbroken phase. Spontaneous breaking of the continuous symmetries always generates various excitations with varying mass spectra. Axion is one of that type, generated via spontaneous breaking of a global Chiral U(1) symmetry named after its discoverers, Peccei and Queen. This symmetry...

The lattice regularization of the Higgs sector of the standard model is summarized. The triviality bound and vacuum instability bound are described. The question of chiral gauge theories is discussed. Some aspects of the numerical simulations of the electroweak phase transition are considered. 1. Lattice regularization of the Higgs sector The masses of the elementary particles in the standard m...

Spontaneous symmetry breaking is a general principle that constitutes the underlying concept of a vast number of physical phenomena ranging from ferromagnetism and superconductivity in condensed matter physics to the Higgs mechanism in the standard model of elementary particles. I focus on manifestations of spontaneously broken symmetries in systems that are not Lorentz invariant, which include...

We present a new solution for the problem of ultra high energy cosmic ray events with energy up to 3 10 20 eV. Various authors have considered that these events are caused by the decay of supermassive particles emitted by topological defects formed during the symmetry breaking of a GUT. However, in the frame work of supersymmetric theories, the decay of topo-logical defects should produce not o...

It has recently been proposed that all fundamental fermion masses (whether Dirac or Majorana) come from effective dimension-five operators in the context of a truly minimal left-right model. We show how a particularly economical scheme emerges in a supersymmetric framework, where chiral symmetry breaking originates in the gaugino sector. In the standard model of particle interactions, the spont...

It has recently been proposed that all fundamental fermion masses (whether Dirac or Majorana) come from effective dimension-five operators in the context of a truly minimal left-right model. We show how a particularly economical scheme emerges in a supersymmetric framework, where chiral symmetry breaking originates in the gaugino sector. In the Standard Model of particle interactions, the spont...

Supersymmetry (Susy) provides an attractive scenario to account for the amount of dark matter in the universe. If R-parity is conserved, the lightest supersymmetric particle (LSP) is stable and an ideal dark matter candidate. A very interesting option is the spin 3/2 gravitino G̃. The mass of the gravitino is set by the Susy breaking scale F via m3/2 = mG̃ = F/ √ 3 MP , with MP ' 2.4 · 10 GeV the...