Topics in Quantum Chromodynamics and Baryogenesis.
This work attempts to give answers to two questions in elementary particle physics. The first problem discussed deals with the Baryon Asymmetry of the Universe (BAU), the observed asymmetry between baryons and anti-baryons in the Universe today. Although the Standard Model (SM) of elementary particles is presently the most successful theory which attempts to describe the interactions in the microworld, the amount of baryon asymmetry which can be created in the SM turns out to be much smaller than that observed. The simplest model which allows the possibility of Baryogenesis is the Minimal Supersymmetric Standard Model. From the experimentally observed BAU, I impose stringent constraints on the parameters of this model which can be tested in proposed experiments. The second problem described concerns the low -energy behavior of Quantum Chromodynamics (QCD). Phenomena in this domain can be described within a formalism of Effective Field Theories which uses only a small subset of relevant fields. An important question then is to determine a set of coupling constants in the low-energy expansion of interactions among these fields. This has been done in the past by extracting information from experiments. An important test of QCD is to derive these coefficients from the theory. However, this has so far proven to be a formidable task because it is outside of the domain of the major theoretical tool one has for dealing with such phenomena, namely perturbation theory. Since Lattice Gauge Theories have been created precisely for the task of dealing with the non-perturbative aspects of field theories it is natural to employ them to derive the coefficients. Here a formalism is described which allows this to be done both analytically in the strong-coupling domain and numerically in the continuum limit. As an application, the coefficients of the chiral Lagrangian at the leading order in the strong -coupling large-N expansion are computed.
- Pub Date:
- January 1995
- Physics: Elementary Particles and High Energy