Mark Srednicki

A Simple Solution to the Strong CP Problem with a Harmless Axion

We describe a simple generalization of the Peccei-Quinn mechanism which eliminates the strong CP problem at the cost of a very light, very weakly coupled axion. The mechanism requires no new fermions and is easily implemented in grand unified theories.

Supersymmetric grand unified theories and the early universe

Abstract Consequences of supersymmetric, grand unified theories (with supersymmetry unnbroken at the tree level) for the production of baryons and magnetic monopoles in the early universe are discussed.

MORE SUPERSYMMETRIC TECHNICOLOR

Abstract We propose a supersymmetric model of particle physics in which supersymmetry is broken by strong gauge forces. Unlike previous realistic supersymmetric technicolor theories, the model contains only one extra strong gauge group, and it lends itself readily to grand unification. The model also has no light axions which can burn out stars. A variety of new particles, many weighing less than 100 GeV, are predicted. A no-go theorem due to Witten is discussed.

NONGRAVITATIONAL DECAY OF COSMIC STRINGS

We investigate the decay of loops of cosmic string via radiation of nongravitational energy. We show that emission of particles other than gravitons and Goldstone bosons is not significant. We use methods which are considerably more rigorous than those used in the past to draw similar conclusions.

More on cosmology for supersymmetric GUTS

Abstract It is argued that phase transitions which would occur at finite temperatures in supersymmetric grand unified theories (with supersymmetry unbroken at the tree level) proceed very slowly. In the simplest models, the universe would supercool in a phenomenologically unacceptable phase, essentially forever. Criteria which a supersymmetric GUT must satisfy to avoid this fate are briefly discussed.

Colored monopoles on the lattice

Abstract Monopoles which carry both electro- and chromomagnetic charge are described by introducing new degrees of freedom into the hamiltonian form of SU(3) color × U(1) em lattice gauge theory. The monopoles we discuss exist as classical solutions in the SU(5) grand unified theory. The lattice theory allows us to describe the properties of these monopoles at low energies, where the color forces are strong. Our results are in agreement with a previous analysis by Coleman.

Dynamical symmetry breaking in SO(4n+2) and E(6) gauge theories

Abstract We find that SO(4n+2) and E(6) gauge theories with fermions in the complex spinor representation (and no scalar fields at all) undergo dynamical breaking of the gauge symmetry, according to the rules of Raby, Dimopoulos, and Susskind.

The Hidden Fermions in Z(2) Theories

In 1964, Schultz, Mattis, and Lieb (SML) [1] showed that the two dimensional Ising model is equivalent to a system of locally coupled fermions. After a canonical transformation, these fermions become noninteracting, and so SML were able to construct a simple, elegant, and exact solution. Recently, Fradkin, Susskind, and I (FSS) [2] showed that the three dimensional Z(2) gauge theory [3] could also be rewritten in terms of locally coupled fermionic degrees of freedom. Unfortunately, the coupling turned out to be quartic, and so we were unable to solve the theory.