2,187 research outputs found
Relating Noncommutative SO(2,3) Gravity to the Lorentz-Violating Standard-Model Extension
We consider a model of noncommutative gravity that is based on a spacetime
with broken local SO(2,3) symmetry. We show that the torsion-free version of
this model is contained within the framework of the Lorentz-violating
Standard-Model Extension. We analyze in detail the relation between the
torsion-free, quadratic limits of the broken SO(2,3) model and the
Standard-Model Extension. As part of the analysis,we construct the relevant
geometric quantities to quadratic order in the metric perturbation around a
flat background.Comment: 10 pages, accepted in Symmetr
Relating Noncommutative SO(2,3)* Gravity to the Lorentz-Violating Standard-Model Extension
We consider a model of noncommutative gravity that is based on a spacetime with broken local SO(2,3)* symmetry. We show that the torsion-free version of this model is contained within the framework of the Lorentz-violating Standard-Model Extension (SME). We analyze in detail the relation between the torsion-free, quadratic limits of the broken SO(2,3)* model and the Standard-Model Extension. As part of the analysis, we construct the relevant geometric quantities to quadratic order in the metric perturbation around a flat background
Noncommutative Field Theory and Lorentz Violation
The role of Lorentz symmetry in noncommutative field theory is considered.
Any realistic noncommutative theory is found to be physically equivalent to a
subset of a general Lorentz-violating standard-model extension involving
ordinary fields. Some theoretical consequences are discussed. Existing
experiments bound the scale of the noncommutativity parameter to (10 TeV)^{-2}.Comment: 4 page
Training of Instrumentalists and Development of New Technologies on SOFIA
This white paper is submitted to the Astronomy and Astrophysics 2010 Decadal
Survey (Astro2010)1 Committee on the State of the Profession to emphasize the
potential of the Stratospheric Observatory for Infrared Astronomy (SOFIA) to
contribute to the training of instrumentalists and observers, and to related
technology developments. This potential goes beyond the primary mission of
SOFIA, which is to carry out unique, high priority astronomical research.
SOFIA is a Boeing 747SP aircraft with a 2.5 meter telescope. It will enable
astronomical observations anywhere, any time, and at most wavelengths between
0.3 microns and 1.6 mm not accessible from ground-based observatories. These
attributes, accruing from the mobility and flight altitude of SOFIA, guarantee
a wealth of scientific return. Its instrument teams (nine in the first
generation) and guest investigators will do suborbital astronomy in a
shirt-sleeve environment. The project will invest $10M per year in science
instrument development over a lifetime of 20 years. This, frequent flight
opportunities, and operation that enables rapid changes of science instruments
and hands-on in-flight access to the instruments, assure a unique and extensive
potential - both for training young instrumentalists and for encouraging and
deploying nascent technologies. Novel instruments covering optical, infrared,
and submillimeter bands can be developed for and tested on SOFIA by their
developers (including apprentices) for their own observations and for those of
guest observers, to validate technologies and maximize observational
effectiveness.Comment: 10 pages, no figures, White Paper for Astro 2010 Survey Committee on
State of the Professio
Clock-Comparison Tests of Lorentz and CPT Symmetry in Space
Clock-comparison experiments conducted in space can provide access to many
unmeasured coefficients for Lorentz and CPT violation. The orbital
configuration of a satellite platform and the relatively large velocities
attainable in a deep-space mission would permit a broad range of tests with
Planck-scale sensitivity.Comment: 4 page
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