2,502 research outputs found
A theory of evolving natural constants embracing Einstein's theory of general relativity and Dirac's large number hypothesis
Taking a hint from Dirac's large number hypothesis, we note the existence of
cosmic combined conservation laws that work to cosmologically long time. We
thus modify or generalize Einstein's theory of general relativity with fixed
gravitation constant to a theory for varying , which can be applied to
cosmology without inconsistency, where a tensor arising from the variation of G
takes the place of the cosmological constant term. We then develop on this
basis a systematic theory of evolving natural constants by finding out their cosmic combined counterparts involving factors of
appropriate powers of that remain truly constant to cosmologically long
time. As varies so little in recent centuries, so we take these natural
constants to be constant.Comment: 29 pages, revtex
Detecting interactions between dark matter and photons at high energy colliders
We investigate the sensitivity to the effective operators describing
interactions between dark matter particles and photons at future high energy
colliders via the \gamma+ \slashed{E} channel. Such operators could
be useful to interpret the potential gamma-ray line signature observed by the
Fermi-LAT. We find that these operators can be further tested at
colliders by using either unpolarized or polarized beams. We also derive a
general unitarity condition for processes and apply it to the dark
matter production process .Comment: 13 pages, 8 figure
Entanglement entropy of (3+1)D topological orders with excitations
Excitations in (3+1)D topologically ordered phases have very rich structures.
(3+1)D topological phases support both point-like and string-like excitations,
and in particular the loop (closed string) excitations may admit knotted and
linked structures. In this work, we ask the question how different types of
topological excitations contribute to the entanglement entropy, or
alternatively, can we use the entanglement entropy to detect the structure of
excitations, and further obtain the information of the underlying topological
orders? We are mainly interested in (3+1)D topological orders that can be
realized in Dijkgraaf-Witten gauge theories, which are labeled by a finite
group and its group 4-cocycle up to group
automorphisms. We find that each topological excitation contributes a universal
constant to the entanglement entropy, where is the quantum
dimension that depends on both the structure of the excitation and the data
. The entanglement entropy of the excitations of the
linked/unlinked topology can capture different information of the DW theory
. In particular, the entanglement entropy introduced by Hopf-link
loop excitations can distinguish certain group 4-cocycles from the
others.Comment: 12 pages, 4 figures; v2: minor changes, published versio
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