549,148 research outputs found
Horizons 2021 Annual Impact Report
HSHU’s PILLARS OF PROGRAMMING: HSHU aims to mitigate opportunity disparities faced by Bridgeport families in a county with the largest opportunity gap in the nation. Our organization provides support and empowerment to 168 Bridgeport students through three powerful pillars of programming. These pillars include a K-8 six-week summer program, a K-8 school year program, and a high school program offered in partnership Horizons Bridgeport. Each pillar provides equitable opportunities that include joyful academic and social-emotional learning, and establishing citizenship within community
M-Horizons
We solve the Killing spinor equations and determine the near horizon
geometries of M-theory that preserve at least one supersymmetry. The M-horizon
spatial sections are 9-dimensional manifolds with a Spin(7) structure
restricted by geometric constraints which we give explicitly. We also provide
an alternative characterization of the solutions of the Killing spinor
equation, utilizing the compactness of the horizon section and the field
equations, by proving a Lichnerowicz type of theorem which implies that the
zero modes of a Dirac operator coupled to 4-form fluxes are Killing spinors. We
use this, and the maximum principle, to solve the field equations of the theory
for some special cases and present some examples.Comment: 36 pages, latex. Reference added, minor typos correcte
Stringy Horizons
We argue that classical effects qualitatively modify the
structure of Euclidean black hole horizons in string theory. While low energy
modes experience the geometry familiar from general relativity, high energy
ones see a rather different geometry, in which the Euclidean horizon can be
penetrated by an amount that grows with the radial momentum of the probe. We
discuss this in the exactly solvable SL(2,R)/U(1) black hole, where it is a
manifestation of the black hole/Sine-Liouville duality.Comment: 14 page
Small Horizons
All near horizon geometries of supersymmetric black holes in a N=2, D=5
higher-derivative supergravity theory are classified. Depending on the choice
of near-horizon data we find that either there are no regular horizons, or
horizons exist and the spatial cross-sections of the event horizons are
conformal to a squashed or round S^3, S^1 * S^2, or T^3. If the conformal
factor is constant then the solutions are maximally supersymmetric. If the
conformal factor is not constant, we find that it satisfies a non-linear vortex
equation, and the horizon may admit scalar hair.Comment: 21 pages, latex. Typos corrected and reference adde
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