26,790 research outputs found
On correlation functions of integrable models associated to the six-vertex R-matrix
We derive an analog of the master equation obtained recently for correlation
functions of the XXZ chain for a wide class of quantum integrable systems
described by the R-matrix of the six-vertex model, including in particular
continuum models. This generalized master equation allows us to obtain multiple
integral representations for the correlation functions of these models. We
apply this method to derive the density-density correlation functions of the
quantum non-linear Schrodinger model.Comment: 21 page
Off-Line, Multi-Detector Intensity Interferometers II: Implications and Applications
Intensity interferometry removes the stringent requirements on mechanical
precision and atmospheric corrections that plague all amplitude interferometry
techniques at the cost of severely limited sensitivity. A new idea we recently
introduced, very high redundancy, alleviates this problem. It enables the
relatively simple construction (~1cm mechanical precision) of a ground-based
astronomical facility able to transform a two-dimensional field of point-like
sources to a three-dimensional distribution of micro-arcsec resolved systems,
each imaged in several optical bands. Each system will also have its high
resolution residual timing, high quality (inside each band) spectra and light
curve, emergent flux, effective temperature, polarization effects and perhaps
some thermodynamic properties, all directly measured. All the above attributes
can be measured in a single observation run of such a dedicated facility. We
conclude that after three decades of abandonment optical intensity
interferometry deserves another review, also as a ground-based alternative to
the science goals of space interferometers.Comment: The article has been accepted for publication in MNRA
A remark on zeta functions of finite graphs via quantum walks
From the viewpoint of quantum walks, the Ihara zeta function of a finite
graph can be said to be closely related to its evolution matrix. In this note
we introduce another kind of zeta function of a graph, which is closely related
to, as to say, the square of the evolution matrix of a quantum walk. Then we
give to such a function two types of determinant expressions and derive from it
some geometric properties of a finite graph. As an application, we illustrate
the distribution of poles of this function comparing with those of the usual
Ihara zeta function.Comment: 14 pages, 1 figur
Symmetric Linear Backlund Transformation for Discrete BKP and DKP equation
Proper lattices for the discrete BKP and the discrete DKP equaitons are
determined. Linear B\"acklund transformation equations for the discrete BKP and
the DKP equations are constructed, which possesses the lattice symmetries and
generate auto-B\"acklund transformationsComment: 18 pages,3 figure
Microscopic approach to large-amplitude deformation dynamics with local QRPA inertial masses
We have developed a new method for determining microscopically the
fivedimensional quadrupole collective Hamiltonian, on the basis of the
adiabatic self-consistent collective coordinate method. This method consists of
the constrained Hartree-Fock-Bogoliubov (HFB) equation and the local QRPA
(LQRPA) equations, which are an extension of the usual QRPA (quasiparticle
random phase approximation) to non-HFB-equilibrium points, on top of the CHFB
states. One of the advantages of our method is that the inertial functions
calculated with this method contain the contributions of the time-odd
components of the mean field, which are ignored in the widely-used cranking
formula. We illustrate usefulness of our method by applying to oblate-prolate
shape coexistence in 72Kr and shape phase transition in neutron-rich Cr
isotopes around N=40.Comment: 6pages, talk given at Rutherford Centennial Conference on Nuclear
Physics, 8 - 12 August 2011, The University of Mancheste
Astrophysical Condition on the attolensing as a possible probe for a modified gravity theory
We investigate the wave effect in the gravitational lensing by a black hole
with very tiny mass less than 10^-19 solar mass, which is called attolensing,
motivated by a recent report that the lensing signature might be a possible
probe of a modified gravity theory in the braneworld scenario. We focus on the
finite source size effect and the effect of the relative motion of the source
to the lens, which are influential to the wave effect in the attolensing.
Astrophysical condition that the lensed interference signature can be a probe
of the modified gravity theory is demonstrated. The interference signature in
the microlensing system is also discussed.Comment: Accepted for publication in IJMP
On the standing wave mode of giant pulsations
Both odd-mode and even-mode standing wave structures have been proposed for giant pulsations. Unless a conclusion is drawn on the field-aligned mode structure, little progress can be made in understanding the excitation mechanism of giant pulsations. In order to determine the standing wave mode, we have made a systematic survey of magnetic field data from the AMPTE CCE spacecraft and from ground stations located near the geomagnetic foot point of CCE. We selected time intervals when CCE was close to the magnetic equator and also magnetically close to Syowa and stations in Iceland, and when either transverse or compressional Pc 4 waves were observed at CCE. Magnetograms from the ground stations were then examined to determine if there was a giant pulsation in a given time interval. One giant pulsation was associated with a compressional wave, while no giant pulsation was observed in association with transverse wave events. The CCE magnetic field record for the giant pulsation exhibited a remarkable similarity to a giant pulsation observed from the ATS 6 geostationary satellite near the magnetic equator (Hillebrand et al., 1982). In agreement with Hillebrand et al., we conclude that the compressional nature of the giant pulsation is due to an odd-mode standing wave structure. This conclusion places a strong constraint on the generation mechanism of giant pulsations. In particular, if giant pulsations are excited through the drift bounce resonance of ions with standing Alfvén waves, ω - mωd = ±Nωb, where ω is the wave frequency, m is the azimuthal wave number, ωd is the ion drift frequency,N is an integer, and ωb is the ion bounce frequency, then the resonance must occur at an even N
Laboratory-device configurations for investigating new dusty-plasma equilibria
Two configurations that are designed for laboratory investigations of dusty-plasma equilibria are being prepared for operation. The first configuration has a vertical magnetic field that confines horizontally a vertically oriented, 6.4 cm diameter, low-temperature, alkali-metal-ion plasma column. The plasma is produced via the Q-machine method (Rynn and D\u27Angelo 1960 Rev. Sci. Instrum. 31 1326) with contact-ionized alkali-metal ions and thermionically emitted electrons. The dust grains will be injected to form a small number of horizontal dusty-plasma layers levitated electrostatically above the plasma sheath. The advantage of using a Q-machine plasma source is the insensitivity of its plasma production to the background pressure of neutral particles. The plan is to study the competition between neutral-particle cooling and streaming-ion energization in dusty-plasma crystallization and decrystallization (i.e., freezing and melting) over a wide range of neutral-particle pressure. The second configuration has a large vacuum chamber (2 m diameter, 4 m length) and a large, solenoidal, magnetic field (0.1 T) that will magnetically confine small-diameter dust grains in a large-volume dusty plasma. The advantage of producing a large-volume, dusty plasma in a strong magnetic field is the ability to meet the criterion that the dust gyroradius is much smaller than the dusty-plasma-column diameter. The plan is to study third-component effects in microinstabilities and the influence of size distribution on magnetized dusty-plasma equilibrium and stability
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Wrongful convictions of refugees and asylum seekers: responses by the Criminal Cases Review Commission
The Criminal Cases Review Commission (CCRC) reviews possible miscarriages of justice in England, Wales and Northern Ireland when applicants have exhausted other avenues of appeal, with a view to referring unsafe convictions back to the appeal court. This article considers the CCRC’s handling of applications from refugees and asylum seekers who claim to have been wrongly convicted of entering the UK illegally. These cases commonly relate to people who could not obtain travel documents lawfully and were erroneously advised by defence lawyers that they should plead guilty. The article first examines the sources of these wrongful convictions by reviewing CCRC referrals to the appeal court. It then reviews the CCRC’s wider engagement with other criminal justice agencies in an effort
to prevent further wrongful convictions of refugees and asylum seekers. The failing of the criminal justice agencies to properly protect refugees and asylum seekers reflects a wider anxiety about the negative effects of immigration, and the societal appetite to use punitive measures to control immigration. The article concludes by arguing that the CCRC’s campaign was effective, and
demonstrates the importance of inter-agency communication in preventing miscarriages of justice
A Symmetric Generalization of Linear B\"acklund Transformation associated with the Hirota Bilinear Difference Equation
The Hirota bilinear difference equation is generalized to discrete space of
arbitrary dimension. Solutions to the nonlinear difference equations can be
obtained via B\"acklund transformation of the corresponding linear problems.Comment: Latex, 12 pages, 1 figur
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