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Sterile neutrino dark matter in warped extra dimensions
We consider a (long-lived) sterile neutrino dark matter scenario in a five
dimensional (5D) warped extra dimension model where the fields can live in the
bulk, which is partly motivated from the absence of the absolutely stable
particles in a simple Randall-Sundrum model. The dominant production of the
sterile neutrino can come from the decay of the radion (the scalar field
representing the brane separation) around the electroweak scale. The
suppressions of the 4D parameters due to the warp factor and the small wave
function overlaps in the extra dimension help alleviate the exceeding
fine-tunings typical for a sterile neutrino dark matter scenario in a 4D setup.Comment: Typos corrected and references adde
A Thousand Invisible Cords Binding Astronomy and High-Energy Physics
The traditional realm of astronomy is the observation and study of the
largest objects in the Universe, while the traditional domain of high-energy
physics is the study of the smallest things in nature. But these two sciences
concerned with opposite ends of the size spectrum are, in Muir's words, bound
fast by a thousand invisible cords that cannot be broken. In this essay I
propose that collaborations of astronomers and high-energy physicists on common
problems are beneficial for both fields, and that both astronomy and
high-energy physics can advance by this close and still growing relationship.
Dark matter and dark energy are two of the binding cords I will use to
illustrate how collaborations of astronomers and high-energy physicists on
large astronomical projects can be good for astronomy, and how discoveries in
astronomy can guide high-energy physicists in their quest for understanding
nature on the smallest scales. Of course, the fields have some different
intellectual and collaborative traditions, neither of which is ideal. The
cultures of the different fields cannot be judged to be right or wrong; they
either work or they don't. When astronomers and high-energy physicists work
together, the binding cords can either encourage or choke creativity. The
challenge facing the astronomy and high-energy physics communities is to adopt
the best traditions of both fields. It is up to us to choose wisely.Comment: Why "Fundamentalist" Physics Is Good for Astronomy (in response to
the paper of Simon White, arXiv:0704.2291
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