Searching for Novel Objects in the Electroweak Theory

We explore the Higgs-Gauge configuration space in the standard electroweak theory. We outline a general prescription that uses the non-trivial topology associated with the gauge group of the theory, to find known solutions of the Euclidean classical equations of motion and motivate the existence of novel ones. In Minkowski spacetime we present evidence for the existence of approximate breathers -- long-lived, spatially localized, temporally periodic configurations. We consider heavy fermion quantum fluctuations about static Higgs-Gauge configurations, and argue for the existence of stable fermionic solitons. These could resolve the fermion decoupling puzzle in chiral gauge theories. We describe our search for a fermionic soliton within a spherical ansatz, and discuss the quantum corrected sphaleron and the emergence of new barriers suppressing the decay of heavy fermions. Finally, we consider electroweak strings and how they could give rise to stable multi-quark objects.Comment: M.I.T. Ph.D Thesis; 107 pages, uses mitthesis.cls; v2: added a referenc

Numerical Investigation of Monopole Chains

We present numerical results for chains of SU(2) BPS monopoles constructed from Nahm data. The long chain limit reveals an asymmetric behavior transverse to the periodic direction, with the asymmetry becoming more pronounced at shorter separations. This analysis is motivated by a search for semiclassical finite temperature instantons in the 3D SU(2) Georgi-Glashow model, but it appears that in the periodic limit the instanton chains either have logarithmically divergent action or wash themselves out.Comment: 14 pages, 6 figures; v2 minor changes, published versio

2+1 Dimensional Georgi-Glashow Instantons in Weyl Gauge

Semiclassical instanton solutions in the 3D SU(2) Georgi-Glashow model are transformed into the Weyl gauge. This illustrates the tunneling interpretation of these instantons and provides a smooth regularization of the singular unitary gauge. The 3D Georgi-Glashow model has both instanton and sphaleron solutions, in contrast to 3D Yang-Mills theory which has neither, and 4D Yang-Mills theory which has instantons but no sphaleron, and 4D electroweak theory which has a sphaleron but no instantons. We also discuss the spectral flow picture of fundamental fermions in a Georgi-Glashow instanton background.Comment: 22 pages, 8 figures, revtex4; v2 - references and comments adde