Analogue Models for T and CPT Violation in Neutral-Meson Oscillations

Analogue models for CP violation in neutral-meson systems are studied in a general framework. No-go results are obtained for models in classical mechanics that are nondissipative or that involve one-dimensional oscillators. A complete emulation is shown to be possible for a two-dimensional oscillator with rheonomic constraints, and an explicit example with spontaneous T and CPT violation is presented. The results have implications for analogue models with electrical circuits.Comment: 9 page

Formation of a molecular Bose-Einstein condensate and an entangled atomic gas by Feshbach resonance

Processes of association in an atomic Bose-Einstein condensate, and dissociation of the resulting molecular condensate, due to Feshbach resonance in a time-dependent magnetic field, are analyzed incorporating non-mean-field quantum corrections and inelastic collisions. Calculations for the Na atomic condensate demonstrate that there exist optimal conditions under which about 80% of the atomic population can be converted to a relatively long-lived molecular condensate (with lifetimes of 10 ms and more). Entangled atoms in two-mode squeezed states (with noise reduction of about 30 dB) may also be formed by molecular dissociation. A gas of atoms in squeezed or entangled states can have applications in quantum computing, communications, and measurements.Comment: LaTeX, 5 pages with 4 figures, uses REVTeX

Bose-Einstein condensate collapse: a comparison between theory and experiment

We solve the Gross-Pitaevskii equation numerically for the collapse induced by a switch from positive to negative scattering lengths. We compare our results with experiments performed at JILA with Bose-Einstein condensates of Rb-85, in which the scattering length was controlled using a Feshbach resonance. Building on previous theoretical work we identify quantitative differences between the predictions of mean-field theory and the results of the experiments. Besides the previously reported difference between the predicted and observed critical atom number for collapse, we also find that the predicted collapse times systematically exceed those observed experimentally. Quantum field effects, such as fragmentation, that might account for these discrepancies are discussed.Comment: 4 pages, 2 figure

CsI(Tl) for WIMP dark matter searches

We report a study of CsI(Tl) scintillator to assess its applicability in experiments to search for dark matter particles. Measurements of the mean scintillation pulse shapes due to nuclear and electron recoils have been performed. We find that, as with NaI(Tl), pulse shape analysis can be used to discriminate between electron and nuclear recoils down to 4 keV. However, the discrimination factor is typically (10-15)% better than in NaI(Tl) above 4 keV. The quenching factor for caesium and iodine recoils was measured and found to increase from 11% to ~17% with decreasing recoil energy from 60 to 12 keV. Based on these results, the potential sensitivity of CsI(Tl) to dark matter particles in the form of neutralinos was calculated. We find an improvement over NaI(Tl) for the spin independent WIMP-nucleon interactions up to a factor of 5 assuming comparable electron background levels in the two scintillators.Comment: 16 pages, 8 figures, to be published in Nucl. Instrum. and Meth. in Phys. Res.

Meson masses in large Nf QCD from the Bethe-Salpeter equation

We solve the homogeneous Bethe-Salpeter (HBS) equation for the scalar, pseudoscalar, vector, and axial-vector bound states of quark and anti-quark in large Nf QCD with the improved ladder approximation in the Landau gauge. The quark mass function in the HBS equation is obtained from the Schwinger-Dyson (SD) equation in the same approximation for consistency with the chiral symmetry. Amazingly, due to the fact that the two-loop running coupling of large Nf QCD is explicitly written in terms of an analytic function, large Nf QCD turns out to be the first example in which the SD equation can be solved in the complex plane and hence the HBS equation directly in the time-like region. We find that approaching the chiral phase transition point from the broken phase, the scalar, vector, and axial-vector meson masses vanish to zero with the same scaling behavior, all degenerate with the massless pseudoscalar meson. This may suggest a new type of manifestation of the chiral symmetry restoration in large Nf QCD.Comment: 33 pages, 16 figures. Typos are corrected. Minor corrections and references are added. Version to appear in Phys. Rev.

Depositional environment and apparent age of the Fauske carbonate conglomerate, North Norwegian Caledonides

The Fauske conglomerate represents a rather rare case of a monomict carbonate conglomerate in the Late Neoproterozoic to Silurian, lithostratigraphic successionsof the Norwegian Caledonides. Lithological varieties of this conglomerate unit from the Lovgavlen quarry have a highly decorative quality and are well known in both domestic and international markets under trading names such as 'Norwegian Rose', 'Jaune Rose', 'Norwegian Green', 'Antique Fonce' and 'Hermelin'. The Fauske conglomerate is a 60m-thick unit which rests on either dark grey ('blue') calcite marbles or white dolomite marbles. The latter are jointed and fragmented, and also appear as sedimentary collapse-breccia and debris where they are in direct contact with the conglomerate. Although the Fauske conglomerate has been involved in two main pulses of Caledonian tectonic deformation, which produced an early, syn-metamorphic flattening of the clasts and a later folding or rotation of clasts into a spaced cleavage, the overall sedimentary features are still remarkably well preserved. The Fauske conglomerate unit consists of 25 beds (5 cm to 3 metres thick) comprising landslide, carbonate debris and carbonate breccia-conglomero-breccias-greywacke lithofacies. Blocks, fragments, cobbles, pebbles and smaller clasts are mainly of white dolostone and pink, beige, white and 'blue' calcite marbles. The matrix has a granoblastic texture and similar range in lithology with variable amounts of quartz, fuchsite, sericite, muscovite and chlorite. Within the unit, an upward fining of the clasts is followed by the gradual development of calcareous greywacke layers which show both cross bedding and channelling. The depositional model involves: (i) a locally developed, tectonically unstable carbonate shelf-margin, (ii) a temporary lowering o sea level, (iii) formation of a high-relief, shore-to-basin fault scarp followed by (iv) the development of a channel, with (v) subsequent, long-distance transport of clasts of pink carbonates from the continent-basin margin,w hich were (vi) redeposited together with a carbonate debris (white dolomite and 'blue' calcite marbles) on the tectonically fragmenting edge of a carbonate shelf. Both matrix and pebbles show a similar range in isotopic values: -1.9 to +0.6 per mil (vs. PDB) for 13Ccarb and 0.70896 to 0.70946 for 87Sr/86Sr. The least altered 87Sr/86Sr (0.70896) isotopic value plotted on the calibration curve is consistent with a seawater composition corresponding to ages of 470-475, 505-510 and 520, whereas the least altered 13C carb (-0.6 per mil) value matches only 520 Ma

High-precision determination of transition amplitudes of principal transitions in Cs from van der Waals coefficient C_6

A method for determination of atomic dipole matrix elements of principal transitions from the value of dispersion coefficient C_6 of molecular potentials correlating to two ground-state atoms is proposed. The method is illustrated on atomic Cs using C_6 deduced from high-resolution Feshbach spectroscopy. The following reduced matrix elements are determined < 6S_{1/2} || D || 6P_{1/2} > =4.5028(60) |e| a0 and =6.3373(84) |e| a0 (a0= 0.529177 \times 10^{-8} cm.) These matrix elements are consistent with the results of the most accurate direct lifetime measurements and have a similar uncertainty. It is argued that the uncertainty can be considerably reduced as the coefficient C_6 is constrained further.Comment: 4 pages; 3 fig

The π\pi, K+K^+, and K0K^0 electromagnetic form factors

The rainbow truncation of the quark Dyson-Schwinger equation is combined with the ladder Bethe-Salpeter equation for the meson amplitudes and the dressed quark-photon vertex in a self-consistent Poincar\'e-invariant study of the pion and kaon electromagnetic form factors in impulse approximation. We demonstrate explicitly that the current is conserved in this approach and that the obtained results are independent of the momentum partitioning in the Bethe-Salpeter amplitudes. With model gluon parameters previously fixed by the condensate, the pion mass and decay constant, and the kaon mass, the charge radii and spacelike form factors are found to be in good agreement with the experimental data.Comment: 8 pages, 6 figures, Revte

The Quark-Photon Vertex and the Pion Charge Radius

The rainbow truncation of the quark Dyson-Schwinger equation is combined with the ladder Bethe-Salpeter equation for the dressed quark-photon vertex to study the low-momentum behavior of the pion electromagnetic form factor. With model gluon parameters previously fixed by the pion mass and decay constant, the pion charge radius $r_\pi$ is found to be in excellent agreement with the data. When the often-used Ball-Chiu Ansatz is used to construct the quark-photon vertex directly from the quark propagator, less than half of $r_\pi^2$ is generated. The remainder of $r^2_\pi$ is seen to be attributable to the presence of the $\rho$-pole in the solution of the ladder Bethe-Salpeter equation.Comment: 21 pages, 9 figure

Regularization-independent study of renormalized non-perturbative quenched QED

A recently proposed regularization-independent method is used for the first time to solve the renormalized fermion Schwinger-Dyson equation numerically in quenched QED$_4$. The Curtis-Pennington vertex is used to illustrate the technique and to facilitate comparison with previous calculations which used the alternative regularization schemes of modified ultraviolet cut-off and dimensional regularization. Our new results are in excellent numerical agreement with these, and so we can now conclude with confidence that there is no residual regularization dependence in these results. Moreover, from a computational point of view the regularization independent method has enormous advantages, since all integrals are absolutely convergent by construction, and so do not mix small and arbitrarily large momentum scales. We analytically predict power law behaviour in the asymptotic region, which is confirmed numerically with high precision. The successful demonstration of this efficient new technique opens the way for studies of unquenched QED to be undertaken in the near future.Comment: 20 pages,5 figure