2,641 research outputs found
Soliton solutions of Calogero model in harmonic potential
A classical Calogero model in an external harmonic potential is known to be
integrable for any number of particles. We consider here reductions which play
a role of "soliton" solutions of the model. We obtain these solutions both for
the model with finite number of particles and in a hydrodynamic limit. In the
latter limit the model is described by hydrodynamic equations on continuous
density and velocity fields. Soliton solutions in this case are finite
dimensional reductions of the hydrodynamic model and describe the propagation
of lumps of density and velocity in the nontrivial background.Comment: 25 pages, 2 figure
Political independence, accountability, and the quality of regulatory decision-making
Recent decades have seen a considerable increase in delegation to independent regulatory agencies, which has been justified by reference to the superior performance of these bodies relative to government departments. Yet, the hypothesis that more independent regulators do better work has hardly been tested. We examine the link using a comprehensive measure of the quality of work carried out by competition authorities in 30 Organisation for Economic Co-Operation and Development (OECD) countries, and new data on the design of these organizations. We find that formal independence has a positive and significant effect on quality. Contrary to expectations, though, formal political accountability does not boost regulatory quality, and there is no evidence that it increases the effect of independence by reducing the risk of slacking. The quality of work is also enhanced by increased staffing, more extensive regulatory powers, and spillover effects of a more capable bureaucratic system
Variational Study of Weakly Coupled Triply Heavy Baryons
Baryons made of three heavy quarks become weakly coupled, when all the quarks
are sufficiently heavy such that the typical momentum transfer is much larger
than Lambda_QCD. We use variational method to estimate masses of the
lowest-lying bcc, ccc, bbb and bbc states by assuming they are Coulomb bound
states. Our predictions for these states are systematically lower than those
made long ago by Bjorken.Comment: 31 pages, 5 figure
Are solar neutrino oscillations robust?
The robustness of the large mixing angle (LMA) oscillation (OSC)
interpretation of the solar neutrino data is considered in a more general
framework where non-standard neutrino interactions (NSI) are present. Such
interactions may be regarded as a generic feature of models of neutrino mass.
The 766.3 ton-yr data sample of the KamLAND collaboration are included in the
analysis, paying attention to the background from the reaction ^13C(\alpha,n)
^16O. Similarly, the latest solar neutrino fluxes from the SNO collaboration
are included. In addition to the solution which holds in the absence of NSI
(LMA-I) there is a 'dark-side' solution (LMA-D) with sin^2 theta_Sol = 0.70,
essentially degenerate with the former, and another light-side solution (LMA-0)
allowed only at 97% CL. More precise KamLAND reactor measurements will not
resolve the ambiguity in the determination of the solar neutrino mixing angle
theta_Sol, as they are expected to constrain mainly Delta m^2. We comment on
the complementary role of atmospheric, laboratory (e.g. CHARM) and future solar
neutrino experiments in lifting the degeneracy between the LMA-I and LMA-D
solutions. In particular, we show how the LMA-D solution induced by the
simplest NSI between neutrinos and down-type-quarks-only is in conflict with
the combination of current atmospheric data and data of the CHARM experiment.
We also mention that establishing the issue of robustness of the oscillation
picture in the most general case will require further experiments, such as
those involving low energy solar neutrinos.Comment: 13 pages, 6 figures; Final version to appear in JHE
Some non perturbative calculations on spin glasses
Models of spin glasses are studied with a phase transition discontinuous in
the Parisi order parameter. It is assumed that the leading order corrections to
the thermodynamic limit of the high temperature free energy are due to the
existence of a metastable saddle point in the replica formalism. An ansatz is
made on the form of the metastable point and its contribution to the free
energy is calculated. The Random Energy Model is considered along with the
p-spin and the p-state Potts Models in their p < infinity expansion.Comment: 12 pages, LaTe
Ultraperipheral photoproduction of vector mesons in the nuclear Coulomb field and the size of neutral vector mesons
We point out a significance of ultraperipheral photoproduction of vector
mesons in the Coulomb field of nuclei as a means of measuring the radius of the
neutral vector meson. This new contribution to the production amplitude is very
small compared to the conventional diffractive amplitude, but because of large
impact parameters inherent to the ultraperipheral Coulomb mechanism its impact
on the diffraction slope is substantial. We predict appreciable and strongly
energy dependent increase of the diffraction slope towards very small momentum
transfer.The magnitude of the effect is proportional to the mean radius squared
of the vector meson and is within the reach of high precision photoproduction
experiments, which gives a unique experimental handle on the size of vector
mesons
Dual Superconductors and SU(2) Yang-Mills
We propose that the SU(2) Yang-Mills theory can be interpreted as a two-band
dual superconductor with an interband Josephson coupling. We discuss various
consequences of this interpretation including electric flux quantization,
confinement of vortices with fractional flux, and the possibility that a closed
vortex loop exhibits exotic exchange statistics
Film support and the challenge of ‘sustainability’: on wing design, wax and feathers, and bolts from the blue
In recognition of the importance of film in generating both economic and cultural value, the UK Labour government set up a new agency – the United Kingdom Film Council (UKFC) – in 2000 with a remit to build a sustainable film industry. But, reflecting a plethora of differing expectations in relation to the purposes behind public support for film, the UKFC's agenda shifted and broadened over the organisation's lifetime (2000–11). Apparently unconvinced by the UKFC's achievements, the Coalition government which came to power in May 2010 announced the Council's abolition and reassigned its responsibilities as part of a general cost-cutting strategy. Based on original empirical research, this article examines how the UKFC's sense of strategic direction was determined, how and why the balance of objectives it pursued changed over time and what these shifts tell us about the nature of film policy and the challenges facing bodies that are charged with enacting it in the twenty-first century
Effective Potential for Uniform Magnetic Fields through Pauli Interaction
We have calculated the explicit form of the real and imaginary parts of the
effective potential for uniform magnetic fields which interact with spin-1/2
fermions through the Pauli interaction. It is found that the non-vanishing
imaginary part develops for a magnetic field stronger than a critical field,
whose strength is the ratio of the fermion mass to its magnetic moment. This
implies the instability of the uniform magnetic field beyond the critical field
strength to produce fermion pairs with the production rate density
in the
presence of Pauli interaction.Comment: 9 pages with 1 figur
The Use of Dispersion Relations in the and Coupled-Channel System
Systematic and careful studies are made on the properties of the IJ=00
and coupled-channel system, using newly derived dispersion
relations between the phase shifts and poles and cuts. The effects of nearby
branch point singularities to the determination of the resonance are
estimated and and discussed.Comment: 22 pages with 5 eps figures. A numerical bug in previous version is
fixed, discussions slightly expanded. No major conclusion is change
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