2,541 research outputs found
Stable p-branes in Chern-Simons AdS supergravities
We construct static codimension-two branes in any odd dimension D, with
negative cosmological constant, and show that they are exact solutions of
Chern-Simons (super)gravity theory for (super)AdS coupled to external sources.
The stability of these solutions is analyzed by counting the number of
preserved supersymmetries. It is shown that static massive (D-3)-branes are
unstable unless some suitable gauge fields are added and the brane is extremal.
In particular, in three dimensions, a 0-brane is recognized as the negative
mass counterpart of the BTZ black hole. For these 0-branes, we write explicitly
electromagnetically charged BPS states with various number of preserved
supersymmetries within the OSp(p|2) x OSp(q|2) supergroups. In five dimensions,
we prove that stable 2-branes with electromagnetic charge always exist for the
generic supergroup SU(2,2|N), where N is different than 4. For the special case
N=4, in which the CS supergravity requires the addition of a nontrivial gauge
field configuration in order to preserve maximal number of degrees of freedom,
we show for two different static 2-branes that they are BPS states (one of
which is the ground state), and from the corresponding algebra of charges we
show that the energy is bounded from below. In higher dimensions, our results
admit a straightforward generalization, although there are presumably more
solutions corresponding to different intersections of the elementary objects.Comment: 43 pages, revtex4.cls; v2: slight amendments and references added to
match published versio
Self-dual solitons in N=2 supersymmetric semilocal Chern-Simons theory
We embed the semilocal Chern-Simons-Higgs theory into an N=2 supersymmetric
system. We construct the corresponding conserved supercharges and derive the
Bogomol'nyi equations of the model from supersymmetry considerations. We show
that these equations hold provided certain conditions on the coupling constants
as well as on the Higgs potential of the system, which are a consequence of the
huge symmetry of the theory, are satisfied. They admit string-like solutions
which break one half of the supersymmetries --BPS Chern-Simons semilocal cosmic
strings-- whose magnetic flux is concentrated at the center of the vortex. We
study such solutions and show that their stability is provided by supersymmetry
through the existence of a lower bound for the energy, even though the manifold
of the Higgs vacuum does not contain non-contractible loops.Comment: 12 pages, LaTeX, no figures, to appear in Modern Physics Letters
Let's Twist Again: General Metrics of G(2) Holonomy from Gauged Supergravity
We construct all complete metrics of cohomogeneity one G(2) holonomy with S^3
x S^3 principal orbits from gauged supergravity. Our approach rests on a
generalization of the twisting procedure used in this framework. It corresponds
to a non-trivial embedding of the special Lagrangian three-cycle wrapped by the
D6-branes in the lower dimensional supergravity. There are constraints that
neatly reduce the general ansatz to a six functions one. Within this approach,
the Hitchin system and the flop transformation are nicely realized in eight
dimensional gauged supergravity.Comment: 31 pages, latex; v2: minor changes, references adde
Supersymmetric Electroweak Cosmic Strings
We study the connection between supersymmetry and a topological bound
in a two-Higgs-doublet system with an gauge group. We derive the Bogomol'nyi equations from
supersymmetry considerations showing that they hold provided certain conditions
on the coupling constants, which are a consequence of the huge symmetry of the
theory, are satisfied. Their solutions, which can be interpreted as electroweak
cosmic strings breaking one half of the supersymmetries of the theory, are
studied. Certain interesting limiting cases of our model which have recently
been considered in the literature are finally analyzed.Comment: 20 pages, RevTe
Externally Dispersed Interferometry for Precision Radial Velocimetry
Externally Dispersed Interferometry (EDI) is the series combination of a
fixed-delay field-widened Michelson interferometer with a dispersive
spectrograph. This combination boosts the spectrograph performance for both
Doppler velocimetry and high resolution spectroscopy. The interferometer
creates a periodic spectral comb that multiplies against the input spectrum to
create moire fringes, which are recorded in combination with the regular
spectrum. The moire pattern shifts in phase in response to a Doppler shift.
Moire patterns are broader than the underlying spectral features and more
easily survive spectrograph blurring and common distortions. Thus, the EDI
technique allows lower resolution spectrographs having relaxed optical
tolerances (and therefore higher throughput) to return high precision velocity
measurements, which otherwise would be imprecise for the spectrograph alone.Comment: 7 Pages, White paper submitted to the AAAC Exoplanet Task Forc
Type I Superconductivity upon Monopole Condensation in Seiberg-Witten Theory
We study the confinement scenario in N=2 supersymmetric SU(2) gauge theory
near the monopole point upon breaking of N=2 supersymmetry by the adjoint
matter mass term. We confirm claims made previously that the
Abrikosov-Nielsen-Olesen string near the monopole point fails to be a BPS state
once next-to-leading corrections in the adjoint mass parameter taken into
account. Our results shows that type I superconductivity arises upon monopole
condensation. This conclusion allows us to make qualitative predictions on the
structure of the hadron mass spectrum near the monopole point.Comment: LaTex, 25 pages. Minor changes. To be published in NP
Spin Susceptibility of Noncentrosymmetric Heavy-fermion Superconductor CeIrSi3 under Pressure: 29Si-Knight Shift Study on Single Crystal
We report 29Si-NMR study on a single crystal of the heavy-fermion
superconductor CeIrSi3 without an inversion symmetry along the c-axis. The
29Si-Knight shift measurements under pressure have revealed that the spin
susceptibility for the ab-plane decreases slightly below Tc, whereas along the
c-axis it does not change at all. The result can be accounted for by the spin
susceptibility in the superconducting state being dominated by the strong
antisymmetric (Rashba-type) spin-orbit interaction that originates from the
absence of an inversion center along the c-axis and it being much larger than
superconducting condensation energy. This is the first observation which
exhibits an anisotropy of the spin susceptibility below Tc in the
noncentrosymmetric superconductor dominated by strong Rashba-type spin-orbit
interaction.Comment: 4 pages, 4 figures, Accepted for publication in Phys. Rev. Let
Phases of dual superconductivity and confinement in softly broken N=2 supersymmetric Yang-Mills theories
We study the electric flux tubes that undertake color confinement in N=2
supersymmetric Yang-Mills theories softly broken down to N=1 by perturbing with
the first two Casimir operators. The relevant Abelian Higgs model is not the
standard one due to the presence of an off-diagonal coupling among different
magnetic U(1) factors. We perform a preliminary study of this model at a
qualitative level. BPS vortices are explicitely obtained for particular values
of the soft breaking parameters. Generically however, even in the ultrastrong
scaling limit, vortices are not critical but live in a "hybrid" type II phase.
Also, ratios among string tensions are seen to follow no simple pattern. We
examine the situation at the half Higgsed vacua and find evidence for solutions
with the behaviour of superconducting strings. In some cases they are solutions
to BPS equations.Comment: 15 pages, 1 figure, revtex; v2: typos corrected, final versio
Prepotential and Instanton Corrections in N=2 Supersymmetric SU(N_1)xSU(N_2) Yang Mills Theories
In this paper we analyse the non-hyperelliptic Seiberg-Witten curves derived
from M-theory that encode the low energy solution of N=2 supersymmetric
theories with product gauge groups. We consider the case of a SU(N_1)xSU(N_2)
gauge theory with a hypermultiplet in the bifundamental representation together
with matter in the fundamental representations of SU(N_1) and SU(N_2). By means
of the Riemann bilinear relations that hold on the Riemann surface defined by
the Seiberg--Witten curve, we compute the logarithmic derivative of the
prepotential with respect to the quantum scales of both gauge groups. As an
application we develop a method to compute recursively the instanton
corrections to the prepotential in a straightforward way. We present explicit
formulas for up to third order on both quantum scales. Furthermore, we extend
those results to SU(N) gauge theories with a matter hypermultiplet in the
symmetric and antisymmetric representation. We also present some non-trivial
checks of our results.Comment: 21 pages, 2 figures, minor changes and references adde
Microscopic Mechanism and Pairing Symmetry of Superconductivity in the Noncentrosymmetric Heavy Fermion Systems CeRhSI and CeIrSi
We study the pairing symmetry of the noncentrosymmetric heavy fermion
superconductors CeRhSi and CeIrSi under pressures, which are both
antiferromagnets at ambient pressure. We solve the Eliashberg equation by means
of the random phase approximation and find that the mixed state of extended
s-wave and p-wave rather than the wave state could be realized by
enhanced antiferromagnetic spin fluctuations. It is elucidated that the gap
function has line nodes on the Fermi surface and the resulting density of state
in the superconducting state shows a similar character to that of usual d-wave
superconductors, resulting in the NMR relaxation rate that exhibits
no coherence peak and behaves like at low temperatures
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