29192860
New bounce solutions and vacuum tunneling in de Sitter spacetime
I describe a class of oscillating bounce solutions to the Euclidean field equations for gravity coupled to a scalar field theory with multiple vacua. I discuss their implications for vacuum tunneling transitions and for elucidating the thermal nature of de Sitter spacetime.
43214237
Decay of the true vacuum in curved space-time.
A field theory whose potential contains more than one stable or metastable minimum is considered. It is shown that if the vacuum energies are greater than zero gravitational effects make it possible for bubbles of a higher-energy ''false vacuum'' to nucleate and expand within a homogeneous region of a lower-energy ''true vacuum.'' A consequence of this is that in a de Sitter or de Sitter-like space-time any initial state will eventually evolve to a unique statistical mixture of all possible vacua. If the vacuum energies are relatively close, this statistical mixture can be described as a collection of subsystems in thermal equilibrium at the Hawking temperature.
7389353
Duality and Massless Monopoles
Duality arguments suggest the existence of massless magnetic monopoles in gauge theories with the symmetry broken to a non-Abelian subgroup. I discuss how these arise and show how they are manifested as clouds of massless fields surrounding massive monopoles. The dynamics of these clouds is discussed, and the scattering of massless monopole clouds and massive monopoles is described.
123129053
Cosmological Consequences of a First Order Phase Transition in the SU(5) Grand Unified Model
The S${\mathrm{U}}_{5}$ grand unified model is considered in the context of big-bang cosmology. If the Higgs potential contains a cubic term there is a first-order transition to the S${\mathrm{U}}_{3}$\ifmmode\times\else\texttimes\fi{}S${\mathrm{U}}_{2}$\ifmmode\times\else\texttimes\fi{}${\mathrm{U}}_{1}$-symmetric phase. The bubble nucleation rate for this transition is calculated. For typical choices of parameters, the transition proceeds according to one of two scenarios depending on whether or not its rate is ever large relative to the expansion rate of the universe. Both possibilities lead to difficulties: In the former case the transition is rapidly completed, but leads to the production of too many superheavy magnetic monopoles. In the latter case monopole production is suppressed, but there is an extreme supercooling from which the universe never recovers.
44633181
Instabilities of magnetically charged black holes.
The stability of the magnetically charged Reissner-Nordstroem black hole solution is investigated in the context of a theory with massive charged vector mesons. By exploiting the spherical symmetry of the problem, the linear perturbations about the Reissner-Nordstroem solution can be decomposed into modes of definite angular momentum [ital J]. For each value of [ital J], unstable modes appear if the horizon radius is less than a critical value that depends on an anomalous magnetic moment coupling [ital g] and the monopole magnetic charge [ital q]/[ital e]. It is shown that such a critical radius exists (except in the case [ital q]=1/2 with 0[le][ital g][le]2), provided only that the vector meson mass is not too close to the Planck mass. The value of the critical radius is determined numerically for a number of values of [ital J]. The instabilities found here imply the existence of stable solutions with nonzero vector fields ( hair'') outside the horizon; unless [ital q]=1 and [ital g][gt]0, these will not be spherically symmetric.
11583563
Charged black holes with scalar hair.
We describe a family of static black-hole solutions arising in a theory with Einstein gravity coupled to electromagnetism and an axionlike scalar field. These solutions carry both electric and magnetic charge. In addition, the scalar field is spatially varying outside the horizon. Since this nontrivial scalar field is not required by any conservation law, these solutions shed further light on the black-hole no-hair conjecture.
118624605
Finite size scaling in minimal walking technicolor
We compare observables to the finite size scaling hypothesis in SU(2) lattice gauge theory with two Dirac fermions in the adjoint representation. The fits that we obtain yield an estimate of the anomalous mass dimension that is consistent with four loop perturbation theory: $\gamma = 0.51 \pm 0.16$, with the error due to systematic uncertainties in the finite size scaling analysis. The result is somewhat larger than one Schr\"odinger functional study (by 1.3$\sigma$) but consistent with another.