4,184 research outputs found
Exact Description of Rotational Waves in an Elastic Solid
Conventional descriptions of transverse waves in an elastic solid are limited
by an assumption of infinitesimally small gradients of rotation. By assuming a
linear response to variations in orientation, we derive an exact description of
a restricted class of rotational waves in an ideal isotropic elastic solid. The
result is a nonlinear equation expressed in terms of Dirac bispinors. This
result provides a simple classical interpretation of relativistic quantum
mechanical dynamics. We construct a Lagrangian of the form L=-E+U+K=0, where E
is the total energy, U is the potential energy, and K is the kinetic energy.Comment: 9 pages; Added references in revisio
Gluonic charmonium resonances at BaBar and Belle?
We confront predictions for hybrid charmonium and other gluonic excitations
in the charm region with recently observed structures in the mass range above 3
GeV. The Y(4260), if resonant, is found to agree with expectations for hybrid
charmonium. The possibility that other gluonic excitations may be influencing
the data in this region is discussed.Comment: 13 pages, LaTe
Equivalent variational approaches to biaxial liquid crystal dynamics
Within the framework of liquid crystal flows, the Qian & Sheng (QS) model for
Q-tensor dynamics is compared to the Volovik & Kats (VK) theory of biaxial
nematics by using Hamilton's variational principle. Under the assumption of
rotational dynamics for the Q-tensor, the variational principles underling the
two theories are equivalent and the conservative VK theory emerges as a
specialization of the QS model. Also, after presenting a micropolar variant of
the VK model, Rayleigh dissipation is included in the treatment. Finally, the
treatment is extended to account for nontrivial eigenvalue dynamics in the VK
model and this is done by considering the effect of scaling factors in the
evolution of the Q-tensor.Comment: 8 pages. Third versio
Transitions and progress: teachers' views of progress in attainment of pupils age 5-10
There has been a longstanding concern in England and Wales with the year on year progress made by pupils, but particularly at times of change, such as transfer from primary to secondary school at age 11. In Coalton, a former mining town in the North of England, a five year UK government funded initiative known as Charter for Transition has been put in place to try to overcome some of these difficulties and improve the learning opportunities for pupils aged 5-16. The programme takes place over a 5-year period in various stages, but in this paper we make use of data from the first two years. The research team examines the viewpoints of teachers from schools that were receiving additional support in their efforts to raise achievement in phase one and the pilot phase of the project about what they saw as the main benefits of this work. We present the beginnings of our exploration of teachers’ judgements of this work, and what they saw as the difficulties with associating the project with pupil attainment.</p
Nuclear Shadowing in the Structure Function
Nuclear modification of the structure function is investigated.
Although it could be estimated in the medium and large regions from the
nuclear structure function , it is essentially unknown at small . The
nuclear structure function at small is investigated in two
different theoretical models: a parton-recombination model with rescaling
and an aligned-jet model. We find that these models predict completely
different behavior at small : {\it antishadowing} in the first parton model
and {\it shadowing} in the aligned-jet model. Therefore, studies of the ratio
at small could be useful in discriminating among different
models, which produce similar shadowing behavior in the structure function
. We also estimate currently acceptable nuclear modification of at
small by using experimental data and baryon-number
conservation.Comment: 10 pages, Latex, Figs.1 and 2 are not included, Complete postscript
file including the figures is available at
ftp://ftp.cc.saga-u.ac.jp/pub/paper/riko/quantum1/saga-he-78.ps.gz or at
http://www.cc.saga-u.ac.jp/saga-u/riko/physics/quantum1/structure.htm
Two-photon mediated resonance production in e+e- collisions: cross sections and density matrices
Earlier described model amplitudes are used in this paper to evaluate both
cross sections and density matrices for two-photon mediated resonance
production in e^+e^- collisions. All 25 q\bar{q} low-lying ^1S_0, ^3P_J and
^1D_2 resonances can thus be treated. Two independent methods are described to
obtain the resonance production density matrices and cross sections. These
density matrices combined with a resonance decay density matrix give the
detailed angular distributions of the resonance decay products. For two
particular decays, \chi_{c2},\chi_{c1}\to\gamma J/\psi the details are given.
Several numerical results are presented as well.Comment: 27 pages, 4 figure
Epsilon Indi Ba/Bb: the nearest binary brown dwarf
We have carried out high angular resolution near-infrared imaging and
low-resolution (R~1000) spectroscopy of the nearest known brown dwarf, Eps Indi
B, using the ESO VLT NAOS/CONICA adaptive optics system. We find it to be a
close binary (as also noted by Volk et al. 2003) with an angular separation of
0.732 arcsec, corresponding to 2.65AU at the 3.626pc distance of the Eps Indi
system. In our discovery paper (Scholz et al. 2003), we concluded that Eps Indi
B was a ~50Mjup T2.5 dwarf: our revised finding is that the two system
components (Eps Indi Ba and Eps Indi Bb) have spectral types of T1 and T6,
respectively, and estimated masses of 47 and 28Mjup, respectively, assuming an
age of 1.3Gyr. Errors in the masses are +/-10 and +/-7Mjup, respectively,
dominated by the uncertainty in the age determination (0.8-2Gyr range). This
uniquely well-characterised T dwarf binary system should prove important in the
study of low-mass, cool brown dwarfs. The two components are bright and
relatively well-resolved: Eps Indi B is the only T dwarf binary in which
spectra have been obtained for both components. They have a well-established
distance and age. Finally, their orbital motion can be measured on a fairly
short timescale (nominal orbital period 15 yrs), permitting an accurate
determination of the true total system mass, helping to calibrate brown dwarf
evolutionary models.Comment: Accepted for publication by Astronomy & Astrophysics main journal.
This replacement version includes minor changes made following comments by
the referee, along with a reworking of the photometric data and derived
quantities using 2MASS catalogue photometry as the basis, with only a minor
impact on the final result
Glueball enhancements in p(gamma,VV)p through vector meson dominance
Double vector meson photoproduction, p(gamma, G -> VV)p, mediated by a scalar
glueball G is investigated. Using vector meson dominance (VMD) and
Regge/pomeron phenomenology, a measureable glueball enhancement is predicted in
the invariant VV = rho rho and omega omega mass spectra. The scalar glueball is
assumed to be the lightest physical state on the daughter pomeron trajectory
governing diffractive vector meson photoproduction. In addition to cross
sections, calculations for hadronic and electromagnetic glueball decays, G -> V
V' (V,V'= rho, omega, phi, gamma), and gamma_v V -> G transition form factors
are presented based upon flavor universality, VMD and phenomenological
couplings from phi photoproduction analyses. The predicted glueball decay
widths are similar to an independent theoretical study. A novel signature for
glueball detection is also discussed
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