298,648 research outputs found
Unified description of pairing, trionic and quarteting states for one-dimensional SU(4) attractive fermions
Paired states, trions and quarteting states in one-dimensional SU(4)
attractive fermions are investigated via exact Bethe ansatz calculations. In
particular, quantum phase transitions are identified and calculated from the
quarteting phase into normal Fermi liquid, trionic states and spin-2 paired
states which belong to the universality class of linear field-dependent
magnetization in the vicinity of critical points. Moreover, unified exact
results for the ground state energy, chemical potentials and complete phase
diagrams for isospin attractive fermions with external fields
are presented. Also identified are the magnetization plateaux of
and , where is the magnetization saturation value. The
universality of finite-size corrections and collective dispersion relations
provides a further test ground for low energy effective field theory.Comment: 13 pages, 4 figure
High Speed Balancing Applied to the T700 Engine
The work performed under Contracts NAS3-23929 and NAS3-24633 is presented. MTI evaluated the feasibility of high-speed balancing for both the T700 power turbine rotor and the compressor rotor. Modifications were designed for the existing Corpus Christi Army Depot (CCAD) T53/T55 high-speed balancing system for balancing T700 power turbine rotors. Tests conducted under these contracts included a high-speed balancing evaluation for T700 power turbines in the Army/NASA drivetrain facility at MTI. The high-speed balancing tests demonstrated the reduction of vibration amplitudes at operating speed for both low-speed balanced and non-low-speed balanced T700 power turbines. In addition, vibration data from acceptance tests of T53, T55, and T700 engines were analyzed and a vibration diagnostic procedure developed
A reciprocal theorem for a mixture theory
A dynamic reciprocal theorem for a linearized theory of interacting media is developed. The constituents of the mixture are a linear elastic solid and a linearly viscous fluid. In addition to Steel's field equations, boundary conditions and inequalities on the material constants that have been shown by Atkin, Chadwick and Steel to be sufficient to guarantee uniqueness of solution to initial-boundary value problems are used. The elements of the theory are given and two different boundary value problems are considered. The reciprocal theorem is derived with the aid of the Laplace transform and the divergence theorem and this section is concluded with a discussion of the special cases which arise when one of the constituents of the mixture is absent
OH(A-X) fluorescence from photodissociative excitation of HO2 at 157.5 nm
The OH(A-X) fluorescence from photodissociative excitation of HO2 by F2 laser photons (157.5 nm) was observed and compared with the OH fluorescence spectra of H2O2 and the O2+CH3OH mixture. The rotational population distributions of OH(A) were obtained from the fluorescence spectra. The most populated levels are J = 4 for photodissociative excitation of HO2, J = 20 for H2O2, and J = 21 for the O2+CH3OH mixture. The fluorescence from the gas mixture is attributed to the O + H recombination for which the atoms are produced from photodissociation of parent molecules
CP Violation in Heavy MSSM Higgs Scenarios
We introduce and explore new heavy Higgs scenarios in the Minimal
Supersymmetric Standard Model (MSSM) with explicit CP violation, which have
important phenomenological implications that may be testable at the LHC. For
soft supersymmetry-breaking scales M_S above a few TeV and a charged Higgs
boson mass M_H+ above a few hundred GeV, new physics effects including those
from explicit CP violation decouple from the light Higgs boson sector. However,
such effects can significantly alter the phenomenology of the heavy Higgs
bosons while still being consistent with constraints from low-energy
observables, for instance electric dipole moments. To consider scenarios with a
charged Higgs boson much heavier than the Standard Model (SM) particles but
much lighter than the supersymmetric particles, we revisit previous
calculations of the MSSM Higgs sector. We compute the Higgs boson masses in the
presence of CP violating phases, implementing improved matching and
renormalization group (RG) effects, as well as two-loop RG effects from the
effective two-Higgs Doublet Model (2HDM) scale M_H+ to the scale M_S. We
illustrate the possibility of non-decoupling CP-violating effects in the heavy
Higgs sector using new benchmark scenarios named CPX4LHC.Comment: 39 pages, 17 figures, LaTeX, typos correcte
Causality Problem in a Holographic Dark Energy Model
In the model of holographic dark energy, there is a notorious problem of
circular reasoning between the introduction of future event horizon and the
accelerating expansion of the universe. We examine the problem after dividing
into two parts, the causality problem of the equation of motion and the
circular logic on the use of the future event horizon. We specify and isolate
the root of the problem from causal equation of motion as a boundary condition,
which can be determined from the initial data of the universe. We show that
there is no violation of causality if it is defined appropriately and the
circular logic problem can be reduced to an initial value problem.Comment: 5 page
A novel search for gravitationally lensed radio sources in wide-field VLBI imaging from the mJIVE-20 survey
We present a novel pilot search for gravitational lenses in the mJIVE-20
survey, which observed radio sources selected from FIRST with the
VLBA at an angular resolution of 5 mas. We have taken the visibility data for
an initial sources that were detected by the mJIVE-20 observations and
re-mapped them to make wide-field images, selecting fourteen sources that had
multiple components separated by mas, with a flux-ratio of
: and a surface brightness consistent with gravitational lensing.
Two of these candidates are re-discoveries of gravitational lenses found as
part of CLASS. The remaining twelve candidates were then re-observed at 1.4 GHz
and then simultaneously at 4.1 and 7.1 GHz with the VLBA to measure the
spectral index and surface brightness of the individual components as a
function of frequency. Ten were rejected as core-jet or core-hotspot(s)
systems, with surface brightness distributions and/or spectral indices
inconsistent with gravitational lensing, and one was rejected after lens
modelling demonstrated that the candidate lensed images failed the parity test.
The final lens candidate has an image configuration that is consistent with a
simple lens mass model, although further observations are required to confirm
the lensing nature. Given the two confirmed gravitational lenses in the
mJIVE-20 sample, we find a robust lensing-rate of :() for a
statistical sample of 635 radio sources detected on mas-scales, which is
consistent with that found for CLASS.Comment: 31 pages, 22 figures; accepted for publication in MNRA
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