Determing the Properties of Dense Matter: Superconductivity, Bulk Viscosity, and Light Reflection in Compact Stars

In this dissertation, we investigate the properties of matter, denser than nuclei, that exists inside compact stars. First, we examine a mixed superfluid/superconductor system, which likely occurs in neutron star cores. We derive an effective theory of Cooper pair quasiparticles from a microscopic theory of nucleons, and calculate the coupling strengths between quasiparticles. We then calculate the structure of magnetic flux tubes, taking into consideration interactions between neutron and proton Cooper pairs. We find that interactions between the condensates can lead to interesting phenomena and new phases at the border between type-I and type-II behavior. Next, we examine the response of nuclear matter to vibrational modes by calculating the bulk viscosity from purely leptonic processes. We find that for hot neutron stars, the bulk viscosity due to leptons is very small compared to the bulk viscosity due to nucleons, but for cold neutron stars, the leptonic component is dominant. Finally, we derive the reflection and transmission properties of light at boundaries between phases of matter that have two independent U(1) generators, which may exist at the surface of strange stars or at boundaries between different phases of matter in a neutron star

Isospin asymmetry and type-I superconductivity in neutron star matter

It has been argued by Buckley et. al.(Phys. Rev. Lett. 92, 151102, 2004) that nuclear matter is a type-I rather than a type-II superconductor. The suggested mechanism is a strong interaction between neutron and proton Cooper pairs, which arises from an assumed U(2) symmetry of the effective potential, which is supposed to originate in isospin symmetry of the underlying nuclear interactions. To test this claim, we perform an explicit mean-field calculation of the effective potential of the Cooper pairs in a model with a simple four-point pairing interaction. In the neutron star context, matter is very neutron rich with less than 10% protons, so there is no neutron-proton pairing. We find that under these conditions our model shows no interaction between proton Cooper pairs and neutron Cooper pairs at the mean-field level. We estimate the leading contribution beyond mean field and find that it is is small and attractive at weak coupling.Comment: 7 pages, 2 figure

Leptonic contribution to the bulk viscosity of nuclear matter

For beta-equilibrated nuclear matter we estimate the contribution to the bulk viscosity from purely leptonic processes, namely the conversion of electrons to and from muons. For oscillation frequencies in the kiloHertz range, we find that this process provides the dominant contribution to the bulk viscosity when the temperature is well below the critical temperature for superconductivity or superfluidity of the nuclear matter.Comment: 15 pages, LaTeX, new appendix and general clarifications in response to referee comment

Pennsylvania Folklife Vol. 26, No. 4

• Isaac Ziegler Hunsicker: Ontario Schoolmaster and Fraktur Artist • Walls and Fences in Susquehanna County, Pennsylvania • Glossary of Pennsylvania German Terms Related to Construction and Tobacco Agriculture • Pennsylvania German Astronomy and Astrology XV: Benjamin Franklin\u27s Almanacs • Wilhelm Nast and the German Universalists • Vegetables in the Pennsylvania Cuisine: Folk-Cultural Questionnaire No. 47https://digitalcommons.ursinus.edu/pafolklifemag/1072/thumbnail.jp

Flux tubes and the type-I/type-II transition in a superconductor coupled to a superfluid

We analyze magnetic flux tubes at zero temperature in a superconductor that is coupled to a superfluid via both density and gradient (``entrainment'') interactions. The example we have in mind is high-density nuclear matter, which is a proton superconductor and a neutron superfluid, but our treatment is general and simple, modeling the interactions as a Ginzburg-Landau effective theory with four-fermion couplings, including only s-wave pairing. We numerically solve the field equations for flux tubes with an arbitrary number of flux quanta, and compare their energies. This allows us to map the type-I/type-II transition in the superconductor, which occurs at the conventional kappa = 1/sqrt(2) if the condensates are uncoupled. We find that a density coupling between the condensates raises the critical kappa and, for a sufficiently high neutron density, resolves the type-I/type-II transition line into an infinite number of bands corresponding to ``type-II(n)'' phases, in which n, the number of quanta in the favored flux tube, steps from 1 to infinity. For lower neutron density, the coupling creates spinodal regions around the type-I/type-II boundary, in which metastable flux configurations are possible. We find that a gradient coupling between the condensates lowers the critical kappa and creates spinodal regions. These exotic phenomena may not occur in nuclear matter, which is thought to be deep in the type-II region, but might be observed in condensed matter systems.Comment: 14 pages, improved discussion of the effects of varying the neutron/proton condensate ratio; added reference

On the Move: Employment-Related Geographic Mobility: A Review of Socio-Economic Characteristics in Williams Lake

Labour mobility presents numerous opportunities and challenges for communities in rural and small town settings. Opportunities exist in terms of filling much needed service and worker demands, while also presenting the possibility for community growth and stability by attracting new residents and businesses. However, the challenges associated with integrating migrant and transient workers into the fabric of community and maintaining consistent service and worker delivery presses the limited capacity available in rural and small town communities.The purpose of this research is to provide an integrative lens through which to view labour - community dynamics within the On the Move: Employment-Related Mobility in the Canadian Context(E-RGM) project in northern BC. The research is premised on a foundation of comparative community/regional research investigating the differences and similarities in preparation for and management of mineral resource activity in two case study communities/regions: Williams Lake, and Gibraltar mine; and Mackenzie, and the Mt. Milligan mine

Illuminating interfaces between phases of a U(1) x U(1) gauge theory

We study reflection and transmission of light at the interface between different phases of a U(1) x U(1) gauge theory. On each side of the interface, one can choose a basis so that one generator is free (allowing propagation of light), and the orthogonal one may be free, Higgsed, or confined. However, the basis on one side will in general be rotated relative to the basis on the other by some angle alpha. We calculate reflection and transmission coefficients for both polarizations of light and all 8 types of boundary, for arbitrary alpha. We find that an observer measuring the behavior of light beams at the boundary would be able to distinguish 4 different types of boundary, and we show how the remaining ambiguity arises from the principle of complementarity (indistinguishability of confined and Higgs phases) which leaves observables invariant under a global electric/magnetic duality transformation. We also explain the seemingly paradoxical behavior of Higgs/Higgs and confined/confined boundaries, and clarify some previous arguments that confinement must involve magnetic monopole condensation.Comment: RevTeX, 12 page

On the Move: Employment-Related Geographic Mobility: A Review of Socio-Economic Characteristics in Mackenzie

Labour mobility presents numerous opportunities and challenges for communities in rural and small town settings. Opportunities exist in terms of filling much needed service and worker demands, while also presenting the possibility for community growth and stability by attracting new residents and businesses. However, the challenges associated with integrating migrant and transient workers into the fabric of community and maintaining consistent service and worker delivery presses the limited capacity available in rural and small town communities.The purpose of this research is to provide an integrative lens through which to view labour - community dynamics within the On the Move: Employment-Related Mobility in the Canadian Context(ERGM) project in northern BC. The research is premised on a foundation of comparative community/regional research investigating the differences and similarities in preparation for and management of mineral resource activity in two case study communities/regions: Williams Lake, and the Gibraltar Mine; and Mackenzie, and the Mt. Milligan mine

Effects of Large CP-violating Soft Phases on Supersymmetric Electroweak Baryogenesis

We revisit the results of recent electroweak baryogenesis calculations and include all allowed large CP-violating supersymmetric phases. If the phases are large, the resulting baryon asymmetry can be considerably larger than the observed value $n_B/s \sim 4 \times 10^{-11}$. Much of the asymmetry must therefore be washed out, and we argue that the upper bound on the light Higgs mass is larger than the value reported in previous work.Comment: 15 pages, 3 figure