2,234 research outputs found
Scalar mesons nonet in a scaled effective Lagrangian
A scaled SU(3) Nambu - Jona-Lasinio Lagrangian is used to compute the mass of
the nine scalar mesons in the vacuum and the mass of the gluball. It is shown
that a suitable choice of the vacuum gluon condensate allows to reproduce the
experimental masses of the scalar mesons except for the {}(1430). This
choice corresponds to a weak coupling between the gluon and quark condensates,
giving a {}(1500) or a {}(1710) which is nearly a pure glueball.Comment: 12 pages, Latex, use elsart.st
Fitting State Space Models with EViews
This paper demonstrates how state space models can be fitted in EViews. We first briefly introduce EViews as an econometric software package. Next we fit a local level model to the Nile data. We then show how a multivariate âÂÂlatent riskâ model can be developed, making use of the EViews programming environment. We conclude by summarizing the possibilities and limitations of the software package when it comes to state space modeling.
Phase transition and thermodynamics of a hot and dense system in a scaled NJL model
The chiral phase transition of a hot and dense system of quarks is studied
within a modified SU(3) NJL lagrangian that implements the QCD scale anomaly.
The u- and s-quark condensates can feel or not the same chiral restoration
depending on the considered region of the 3-dimension space T_c(\mu_uc,\mu_sc).
The temperature behaviour of the pressure and of the energy and entropy
densities of the u- and s-quark system is investigated. At high temperature,
the non-vanishing bare s-quark mass only modifies slightly the usual behaviour
associated with an ideal quark gas.Comment: 23 pages, LaTeX, uses elsart.sty. This version of the paper includes
the figures (ps
Spontaneous plaquette formation in the SU(4) Spin-Orbital ladder
The low-energy properties of the SU(4) spin-orbital model on a two-leg ladder
are studied by a variety of analytical and numerical techniques. Like in the
case of SU(2) models, there is a singlet-multiplet gap in the spectrum, but the
ground-state is two-fold degenerate. An interpretation in terms of
SU(4)-singlet plaquettes is proposed. The implications for general
two-dimensional lattices are outlined.Comment: 4 pages, 5 Postscript figure
A Secondary Emission-Multiwire Chamber for Ganil Heavy Ion Beams Tuning
http://accelconf.web.cern.ch/AccelConf/c78/papers/f-19.pdfInternational audienc
Fitting State Space Models with EViews
This paper demonstrates how state space models can be fitted in EViews. We first briefly introduce EViews as an econometric software package. Next we fit a local level model to the Nile data. We then show how a multivariate “latent risk” model can be developed, making use of the EViews programming environment. We conclude by summarizing the possibilities and limitations of the software package when it comes to state space modeling
The radiological safety system in GANIL
http://accelconf.web.cern.ch/AccelConf/c81/papers/fp-12.pdfInternational audienc
Spin-mechanics with levitating ferromagnetic particles
We propose and demonstrate first steps towards schemes where the librational
mode of levitating ferromagnets is strongly coupled to the electronic spin of
Nitrogen-Vacancy (NV) centers in diamond. Experimentally, we levitate
ferromagnets in a Paul trap and employ magnetic fields to attain oscillation
frequencies in the hundreds of kHz range with Q factors close to . These
librational frequencies largely exceed the decoherence rate of NV centers in
typical CVD grown diamonds offering prospects for sideband resolved operation.
We also prepare and levitate composite diamond-ferromagnet particles and
demonstrate both coherent spin control of the NV centers and read-out of the
particle libration using the NV spin. Our results will find applications in
ultra-sensitive gyroscopy and bring levitating objects a step closer to
spin-mechanical experiments at the quantum level.Comment: Lengthened to 11 pages. To appear in PR
Spiral-wave-driven accretion in quiescent dwarf nov{\ae}
In dwarf nov{\ae} and low-mass X-ray binaries, the tidal potential excites
spiral waves in the accretion disc. Spiral wave driven accretion may be
important in quiescent discs, where the angular momentum transport mechanism
has yet to be identified. Previous studies were limited to unrealistically high
temperatures for numerical studies or to specific regimes for analytical
studies. We perform the first numerical simulation of spiral wave driven
accretion in the cold temperature regime appropriate to quiescent discs, which
have Mach numbers > 100. We use the new GPU-accelerated finite volume code
Idefix to produce global hydrodynamics 2D simulations of the accretion discs of
dwarf nov{\ae} systems with a fine-enough spatial resolution to capture the
short scale-height of cold, quiescent discs with Mach numbers ranging from 80
to 370. Running the simulations on timescales of tens of binary orbits shows
transient angular momentum transport that decays as the disc relaxes from its
initial conditions. We find the angular momentum parameter {\alpha} drops to
values << 0.01 , too weak to drive accretion in quiescence
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