32,761 research outputs found
Free Fields for Chiral 2D Dilaton Gravity
We give an explicit canonical transformation which transforms a generic
chiral 2D dilaton gravity model into a free field theory.Comment: LaTeX file, 4 pages, to appear in Phys. Rev.
A robust constraint on cosmic textures from the cosmic microwave background
Fluctuations in the cosmic microwave background (CMB) contain information
which has been pivotal in establishing the current cosmological model. These
data can also be used to test well-motivated additions to this model, such as
cosmic textures. Textures are a type of topological defect that can be produced
during a cosmological phase transition in the early universe, and which leave
characteristic hot and cold spots in the CMB. We apply Bayesian methods to
carry out a rigorous test of the texture hypothesis, using full-sky data from
the Wilkinson Microwave Anisotropy Probe. We conclude that current data do not
warrant augmenting the standard cosmological model with textures. We rule out
at 95% confidence models that predict more than 6 detectable cosmic textures on
the full sky.Comment: 5 pages, 2 figures. v2: replaced with version accepted by PRL (minor
amendments to reduce length and address referee comments
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