Vacuum Energy Sequestering: The Framework and Its Cosmological Consequences

Recently we suggested a reformulation of General Relativity which completely sequesters from gravity {\it all} of the vacuum energy from a protected matter sector, assumed to contain the Standard Model. Here we elaborate further on the mechanism, presenting additional details of how it cancels all loop corrections and renders all contributions from phase transitions automatically small. We also consider cosmological consequences in more detail and show that the mechanism is consistent with a variety of inflationary models that make a universe big and old. We discuss in detail the underlying assumptions behind the dynamics of our proposal, and elaborate on the relationship of the physical interpretation of divergent operators in quantum field theory and the apparent `acausality' which our mechanism seems to entail, which we argue is completely harmless. It is merely a reflection of the fact that any UV sensitive quantity in quantum field theory cannot be calculated from first principles, but is an input whose numerical value must be measured. We also note that since the universe should be compact in spacetime, and so will collapse in the future, the current phase of acceleration with $w_{DE}\approx-1$ is just a transient. This could be tested by future cosmological observations.Comment: 39 pages LaTeX, 1 .pdf figure v3: a small correction, version published in PR

Indigenous female entrepeneurship: a qualitative studies in the context of Bolivia

Indigenous entrepreneurship and the gender approach to entrepreneurship are areas that have grown in interest in the entrepreneurship literature in recent years. This paper combines both research streams with the aim of analysing the social and individual factors affecting indigenous quechua female entrepreneurs of Bolivia. Based on the analysis of qualitative data from forty-two face-to-face interviews to indigenous entreprenerurs (female and male), the specific characteristics of these entrepreneurs, the barriers and the facilitators of entrepreneurial activities by women, as well as the role of social capital were extracted. The existence of a sexist and patriarchal culture has been found. However, regarding production, family becomes the production unit; the woman and the man have specific and complementary roles. In addition, there is growing individualism that results in a loss of indigenous values

braneworld cosmology and holography

This thesis is devoted to studying two important aspects of braneworld physics: their cosmology and their holography. We examine the Einstein equations induced on a general (n - 2)-brane of arbitrary tension, embedded in some n-dimensional bulk. The brane energy-momentum tensor enters these equations both linearly and quadratically. From the point of view of a homogeneous and isotropic brane we see quadratic deviations from the FRW equations of the standard cosmology. There is also a contribution from a bulk Weyl tensor. We study this in detail when the bulk is AdS-Schwarzschild or Reissner-Nordstrom AdS. This contribution can be understood holographically. For the AdS-Schwarzschild case, we show that the geometry on a brane near the AdS boundary is just that of a radiation dominated FRW universe. The radiation comes from a field theory that is dual to the AdS bulk. We also develop a new approach which allows us to consider branes that are not near the AdS boundary. This time the dual field theory contributes quadratic energy density/pressure terms to the FRW equations. Remarkably, these take exactly the same form as for additional matter placed on the brane by hand, with no bulk Weyl tensor. We also derive the general equations of motion for a braneworld containing a domain wall. For the critical brane, the induced geometry is identical to that of a vacuum domain wall in (n-l)-dimensional Einstein gravity. We develop the tools to construct a nested Randall-Sundrum scenario whereby we have a "critical" domain wall living on an anti-de Sitter brane. We also show how to construct instantons on the brane, and calculate the probability of false vacuum decay