1,002 research outputs found
A Case Review of G. G. v Gloucester County School Board
In education today, one theme is reoccurring, the question of where and how transgender students fit into our classrooms, our buildings, and on our athletic fields. In G. G. v Gloucester County School Board 20 U.S.C. 1681 § (a); G. G., a minor, transgender male, is attempting to use the boys\u27 restroom at his high school. With the approval of his school administration, G. G. began to use the boys\u27 restroom until the local school board passed a policy banning him from using said restroom. G. G. alleges the board discriminated against him and violated Title IX and the Equal Protection Clause of the Constitution. (G.G. v Gloucester County
Dualities, Twists, and Gauge Theories with Non-Constant Non-Commutativity
We study the world volume theory of D3-branes wrapping the Melvin universe
supported by background NSNS B-field. In the appropriate decoupling limit, the
open string dynamics is that of non-commutative guage field theory with
non-constant non-commutativity. We identify this model as a simple Melvin twist
of flat D3 branes. Along similar lines, one recognizes the model of Hashimoto
and Sethi as being the Melvin null twist, and the model of Dolan and Nappi as
being the null Melvin twist, of the flat D3-brane. This construction therefore
offers a unified perspective on most of the known explicit constructions of
non-commutative gauge theories as a decoupled theory of D-branes in a B-field
background. We also describe the world volume theory on the D3-brane in Melvin
universe which is decaying via the nucleation of monopole anti-monopole pair.Comment: 18 pages, 1 figure, References added, typo correcte
Decay Modes of Intersecting Fluxbranes
Just as the single fluxbrane is quantum mechanically unstable to the
nucleation of a locally charged spherical brane, so intersecting fluxbranes are
unstable to various decay modes. Each individual element of the intersection
can decay via the nucleation of a spherical brane, but uncharged spheres can
also be nucleated in the region of intersection. For special values of the
fluxes, however, intersecting fluxbranes are supersymmetric, and so are
expected to be stable. We explicitly consider the instanton describing the
decay modes of the two--element intersection (an F5-brane in the string theory
context), and show that in dimensions greater than four the action for the
decay mode of the supersymmetric intersection diverges. This observation allows
us to show that stable intersecting fluxbranes should also exist in type 0A
string theory.Comment: 19 pages, 6 figures. References adde
Non-commutative gauge theory on D-branes in Melvin Universes
Non-commutative gauge theory with a non-constant non-commutativity parameter
can be formulated as a decoupling limit of open strings ending on D3-branes
wrapping a Melvin universe. We construct the action explicitly and discuss
various physical features of this theory. The decoupled field theory is not
supersymmetric. Nonetheless, the Coulomb branch appears to remain flat at least
in the large N and large 't Hooft coupling limit. We also find the analogue of
Prasad-Sommerfield monopoles whose size scales with the non-commutativity
parameter and is therefore position dependent.Comment: 15 pages, 1 figure, reference adde
Black diholes in five dimensions
Using a generalized Weyl formalism, we show how stationary, axisymmetric
solutions of the four-dimensional vacuum Einstein equation can be turned into
static, axisymmetric solutions of five-dimensional dilaton gravity coupled to a
two-form gauge field. This procedure is then used to obtain new solutions of
the latter theory describing pairs of extremal magnetic black holes with
opposite charges, known as black diholes. These diholes are kept in static
equilibrium by membrane-like conical singularities stretching along two
different directions. We also present solutions describing diholes suspended in
a background magnetic field, and with unbalanced charges.Comment: 21 pages, 2 figures; reference adde
Granularity-induced gapless superconductivity in NbN films: evidence of thermal phase fluctuations
Using a single coil mutual inductance technique, we measure the low
temperature dependence of the magnetic penetration depth in superconducting NbN
films prepared with similar critical temperatures around 16 K but with
different microstructures. Only (100) epitaxial and weakly granular (100)
textured films display the characteristic exponential dependence of
conventional BCS s-wave superconductors. More granular (111) textured films
exhibit a linear dependence, indicating a gapless state in spite of the s-wave
gap. This result is quantitatively explained by a model of thermal phase
fluctuations favored by the granular structure.Comment: 10 pages, 4 figures, to appear in Phys. Rev.
Abelian Higgs Hair for Electrically Charged Dilaton Black Holes
It is argued that an electronically charged dilaton black hole can support a
long range field of a Nielsen-Olesen string. Combining both numerical and
perturbative techniques we examine the properties of an Abelian-Higgs vortex in
the presence of the black hole under consideration. Allowing the black hole to
approach extremality we found that all fields of the vortex are expelled from
the extreme black hole. In the thin string limit we obtained the metric of a
conical electrically charged dilaton black hole. The effect of the vortex can
be measured from infinity justifying its characterization as black hole hair.Comment: 13 pages, 14 figures, Revtex, to appear in Phys.Rev.D1
Moduli of Abelian varieties, Vinberg theta-groups, and free resolutions
We present a systematic approach to studying the geometric aspects of Vinberg
theta-representations. The main idea is to use the Borel-Weil construction for
representations of reductive groups as sections of homogeneous bundles on
homogeneous spaces, and then to study degeneracy loci of these vector bundles.
Our main technical tool is to use free resolutions as an "enhanced" version of
degeneracy loci formulas. We illustrate our approach on several examples and
show how they are connected to moduli spaces of Abelian varieties. To make the
article accessible to both algebraists and geometers, we also include
background material on free resolutions and representation theory.Comment: 41 pages, uses tabmac.sty, Dedicated to David Eisenbud on the
occasion of his 65th birthday; v2: fixed some typos and added reference
Emergent Electroweak Symmetry Breaking with Composite W, Z Bosons
We present a model of electroweak symmetry breaking in a warped extra
dimension where electroweak symmetry is broken at the UV (or Planck) scale. An
underlying conformal symmetry is broken at the IR (or TeV) scale generating
masses for the electroweak gauge bosons without invoking a Higgs mechanism. By
the AdS/CFT correspondence the W,Z bosons are identified as composite states of
a strongly-coupled gauge theory, suggesting that electroweak symmetry breaking
is an emergent phenomenon at the IR scale. The model satisfies electroweak
precision tests with reasonable fits to the S and T parameter. In particular
the T parameter is sufficiently suppressed since the model naturally admits a
custodial SU(2) symmetry. The composite nature of the W,Z-bosons provide a
novel possibility of unitarizing WW scattering via form factor suppression.
Constraints from LEP and the Tevatron as well as discovery opportunities at the
LHC are discussed for these composite electroweak gauge bosons.Comment: 39 pages, 4 figure
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