2,293 research outputs found
Optimal control for halo orbit missions
This paper addresses the computation of the required trajectory correction
maneuvers (TCM) for a halo orbit space mission to compensate for the launch velocity
errors introduced by inaccuracies of the launch vehicle. By combiningdynamical
systems theory with optimal control techniques, we produce a portrait of the complex
landscape of the trajectory design space. This approach enables parametric studies
not available to mission designers a few years ago, such as how the magnitude of the
errors and the timingof the first TCM affect the correction ÎV. The impetus for
combiningdynamical systems theory and optimal control in this problem arises from
design issues for the Genesis Discovery mission being developed for NASA by the Jet
Propulsion Laboratory
Strong coupling from the Hubbard model
It was recently observed that the one dimensional half-filled Hubbard model
reproduces the known part of the perturbative spectrum of planar N=4 super
Yang-Mills in the SU(2) sector. Assuming that this identification is valid
beyond perturbation theory, we investigate the behavior of this spectrum as the
't Hooft parameter \lambda becomes large. We show that the full dimension
\Delta of the Konishi superpartner is the solution of a sixth order polynomial
while \Delta for a bare dimension 5 operator is the solution of a cubic. In
both cases the equations can be solved easily as a series expansion for both
small and large \lambda and the equations can be inverted to express \lambda as
an explicit function of \Delta. We then consider more general operators and
show how \Delta depends on \lambda in the strong coupling limit. We are also
able to distinguish those states in the Hubbard model which correspond to the
gauge invariant operators for all values of \lambda. Finally, we compare our
results with known results for strings on AdS_5\times S^5, where we find
agreement for a range of R-charges.Comment: 14 pages; v2: 17 pages, 2 figures, appendix and references added;
typos fixed, minor changes; v3 fixed figures; v4 more references added, minor
correctio
Trends and perspectives of the Romanian regional passenger transport
Today, passenger transport has become an indispensable life element, because it offers to the society members many travel possibilities. Modern civilisation, characterised by a massive trade of material and spiritual values, claims a continuous movement of goods and people from a place to another. Transport services are strongly influenced by the transition to the market economy, Romaniaâs geographical position and also by the life standard. The purpose of this paper is to realize a statistical analysis of the main indicators concerning passenger transport for the southern part of Romania, respectively for the historical provinces Muntenia (excluding Bucharest Municipality) and Oltenia
Open Spin Chains in Super Yang-Mills at Higher Loops: Some Potential Problems with Integrability
The super Yang-Mills duals of open strings attached to maximal giant
gravitons are studied in perturbation theory. It is shown that non-BPS baryonic
excitations of the gauge theory can be studied within the paradigm of open
quantum spin chains even beyond the leading order in perturbation theory. The
open spin chain describing the two loop mixing of non-BPS giant gravitons
charged under an su(2) of the so(6) R symmetry group is explicitly constructed.
It is also shown that although the corresponding open spin chain is integrable
at the one loop order, there is a potential breakdown of integrability at two
and higher loops. The study of integrability is performed using coordinate
Bethe ansatz techniques.Comment: 28 pages. References added in revised versio
Some Properties of the Calogero-Sutherland Model with Reflections
We prove that the Calogero-Sutherland Model with reflections (the BC_N model)
possesses a property of duality relating the eigenfunctions of two Hamiltonians
with different coupling constants. We obtain a generating function for their
polynomial eigenfunctions, the generalized Jacobi polynomials. The symmetry of
the wave-functions for certain particular cases (associated to the root systems
of the classical Lie groups B_N, C_N and D_N) is also discussed.Comment: 16 pages, harvmac.te
Crossover from weak to strong coupling regime in dispersive circuit QED
We study the decoherence of a superconducting qubit due to the dispersive
coupling to a damped harmonic oscillator. We go beyond the weak
qubit-oscillator coupling, which we associate with a phase Purcell effect, and
enter into a strong coupling regime, with qualitatively different behavior of
the dephasing rate. We identify and give a physicaly intuitive discussion of
both decoherence mechanisms. Our results can be applied, with small
adaptations, to a large variety of other physical systems, e. g. trapped ions
and cavity QED, boosting theoretical and experimental decoherence studies.Comment: Published versio
Classical Exchange Algebra of the Superstring on S^5 with the AdS-time
A classical exchange algebra of the superstring on S^5 with the AdS-time is
shown on the light-like plane. To this end we use the geometrical method of
which consistency is guaranteed by the classical Yang-Baxter equation. The
Dirac method does not work, there being constraints which contain first-class
and second-class and one can disentangle with each other keeping the isometry
hardly.Comment: 12 pages, v2: argument on alternative representation of S^5 spherical
functions added, typos corrected, one reference added, matches journal
versio
Phase-space theory for dispersive detectors of superconducting qubits
Motivated by recent experiments, we study the dynamics of a qubit
quadratically coupled to its detector, a damped harmonic oscillator. We use a
complex-environment approach, explicitly describing the dynamics of the qubit
and the oscillator by means of their full Floquet state master equations in
phase-space. We investigate the backaction of the environment on the measured
qubit and explore several measurement protocols, which include a long-term full
read-out cycle as well as schemes based on short time transfer of information
between qubit and oscillator. We also show that the pointer becomes measurable
before all information in the qubit has been lost.Comment: 15 pages, 8 figure
The Holographic Dual of 2+1 Dimensional QFTs with N=1 SUSY and Massive Fundamental Flavours
The Maldacena Nastase solution is generalised to include massive fundamental
matter through the addition of a flavour profile. This gives a holographic dual
to N=1 SYM-CS with massive fundamental matter with a singularity free IR. We
study this solution in some detail confirming confinement and asymptotic
freedom. A recently proposed solution generating technique is then applied
which results in a new type-IIA supergravity solution. In a certain limit the
geometry of this solution is asymptotically AdS_4X Y, where Y is the metric at
the base of the Bryant-Salamon G_2 cone, which has topology S^3XS^3.Comment: 31 pages plus appendices, 6 figures. v3: Typos corrected, version to
appear in JHE
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