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

Radiative decays: a new flavour filter

Radiative decays of the $1^3D_1$ orbital excitations of the $\rho$, $\omega$ and $\phi$ to the scalars $f_0(1370)$, $f_0(1500)$ and $f_0(1710)$ are shown to provide a flavour filter, clarifying the extent of glueball mixing in the scalar states. A complementary approach to the latter is provided by the radiative decays of the scalar mesons to the ground-state vectors $\rho$, $\omega$ and $\phi$. Discrimination among different mixing scenarios is strong.Comment: 12 pages, 1 table, 0 figure

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

PG 1700+518 Revisited: Adaptive Optics Imaging and a Revised Starburst Age for the Companion

We present the results of adaptive-optics imaging of the z=0.2923 QSO PG 1700+518 in the J and H bands. The extension to the north of the QSO is clearly seen to be a discrete companion with a well-defined tidal tail, rather than a feature associated with the host galaxy of PG 1700+518 itself. On the other hand, an extension to the southwest of the QSO (seen best in deeper, but lower-resolution, optical images) does likely comprise tidal material from the host galaxy. The SED derived from images in J, H, and two non-standard optical bands indicates the presence of dust intermixed with the stellar component. We use our previously reported Keck spectrum of the companion, the SED found from the imaging data, and updated spectral-synthesis models to constrain the stellar populations in the companion and to redetermine the age of the starburst. While our best-fit age of 0.085 Gyr is nearly the same as our earlier determination, the fit of the new models is considerably better. This age is found to be remarkably robust with respect to different assumptions about the nature of the older stellar component and the effects of dust.Comment: 11 pages; includes two eps figures. Latex (AASTEX). Two additional figures in gif format. Postscript version including all figs. (424 kb) can be obtained from http://www.ifa.hawaii.edu/~canaguby/preprints.html To appear in ApJ. Letter

Colour Confinement and Deformed Baryons in Quantum Chromodynamics

The confinement of coloured entities in Quantum Chromodynamics (QCD) is traced to colour singletness of the observed entities. This is believed to arise from colour singlet state of quark-antiquark for mesons and a fully colour antisymmetric state for baryons. This demands a spherically symmetric baryon in the ground state. However it is pointed out that a deformed baryon in the ground state has been found to be extremely successful phenomenology. There are convincing experimental supports for a deformed nucleon as well. This means that something has been missed in the fundamental theory. In this paper this problem is traced to a new colour singlet state for baryons which has been missed hitherto and incorporation of which provides a consistent justification of a deformed baryon in the ground state. Interestingly this new colour singlet state is global in nature.Comment: 5 pages, 1 figur

The falls efficacy scale international (FES-I): a comprehensive longitudinal validation study

Method: five hundred community-dwelling older people (70-90 years) were assessed on the FES-I in conjunction with demographic, physiological and neuropsychological measures at baseline and at 12 months. Falls were monitored monthly and fear of falling every 3 months. Results: the overall structure and measurement properties of both FES-I scales, as evaluated with item response theory, were good. Discriminative ability on physiological and neuropsychological measures indicated excellent validity, both at baseline (n = 500, convergent validity) and at 1-year follow-up (n = 463, predictive validity). The longitudinal follow-up suggested that FES-I scores increased over time regardless of any fall event, with a trend for a stronger increase in FES-I scores when a person suffered multiple falls in a 3-month period. Additionally, using receiver-operating characteristic (ROC) curves, cut-points were defined to differentiate between lower and higher levels of concern. Conclusions: the current study builds on the previously established psychometric properties of the FES-I. Both scales have acceptable structures, good validity and reliability and can be recommended for research and clinical purposes. Future studies should explore the FES-I's responsiveness to change during intervention studies and confirm suggested cut-points in other settings, larger samples and across different cultures

Constraints on the large-x d/u ratio from electron-nucleus scattering at x>1

Recently the ratio of neutron to proton structure functions F_2n/F_2p was extracted from a phenomenological correlation between the strength of the nuclear EMC effect and inclusive electron-nucleus cross section ratios at x>1. Within conventional models of nuclear smearing, this "in-medium correction" (IMC) extraction constrains the size of nuclear effects in the deuteron structure functions, from which the neutron structure function F_2n is usually extracted. The IMC data determine the resulting proton d/u quark distribution ratio, extrapolated to x=1, to be 0.23 +- 0.09 with a 90% confidence level. This is well below the SU(6) symmetry limit of 1/2 and significantly above the scalar diquark dominance limit of 0.Comment: 4 pages, 3 figure

Two Nucleon-States in a Chiral Quark-Diquark Model

We study the ground and first excited states of nucleons in a chiral quark-diquark model. We include two quark-diquark channels of the scalar-isoscalar and axial-vector-isovector types for the nucleon states. The diquark correlation violating the spin-flavor SU(4)$_{SF}$ symmetry allows to treat the two quark-diquark channels independently. Hence the two states appear as the superpositions of the two quark-diquark channels; one is the nucleon and the other is a state which does not appear in the SU(4)$_{SF}$ quark models. With a reasonable choice of model parameters, the mass of the excited state appears at around 1.5 GeV, which we identify with the Roper resonance N(1440).Comment: 11 pages, 5 figures. Errors are corrected. Conclusions are not affecte

Valence Quark Spin Distribution Functions

The hyperfine interactions of the constituent quark model provide a natural explanation for many nucleon properties, including the Delta-N splitting, the charge radius of the neutron, and the observation that the proton's quark distribution function ratio d(x)/u(x)->0 as x->1. The hyperfine-perturbed quark model also makes predictions for the nucleon spin-dependent distribution functions. Precision measurements of the resulting asymmetries A_1^p(x) and A_1^n(x) in the valence region can test this model and thereby the hypothesis that the valence quark spin distributions are "normal".Comment: 16 pages, 2 Postscript figure

The \rho\rho interaction in the hidden gauge formalism and the f_0(1370) and f_2(1270) resonances

We have studied the interaction of vectors mesons within the hidden gauge formalism and applied it to the particular case of the $\rho \rho$ interaction. We find a strong attraction in the isospin, spin channels I,S=0,0 and 0,2, which is enough to bind the $\rho \rho$ system. We also find that the attraction in the I,S=0,2 channel is much stronger than in the 0,0 case. The states develop a width when the $\rho$ mass distribution is considered, and particularly when the $\pi \pi$ decay channel is turned on. Using a regularization scheme with cut offs of natural size, we obtain results in fair agreement with the mass and the width of the $f_0(1370)$ and $f_2(1270)$ meson states, providing a natural explanation of why the tensor state is more bound than the scalar and offering a new picture for these states, which would be dynamically generated from the $\rho \rho$ interaction or, in simpler words, $\rho \rho$ molecular states.Comment: Version accepted for publicatio