Line-of-sight effects on observability of kink and sausage modes in coronal structures with imaging telescopes

Kink modes of solar coronal structures, perturbing the loop in the direction along the line-of-sight (LOS), can be observed as emission intensity disturbances propagating along the loop provided the angle between the LOS and the structure is not ninety degrees. The effect is based upon the change of the column depth of the loop (along the LOS) by the wave. The observed amplitude of the emission intensity variations can be larger than the actual amplitude of the wave by a factor of two and there is an optimal angle maximizing the observed amplitude. For other angles this effect can also attenuate the observed wave amplitude. The observed amplitude depends upon the ratio of the wave length of kink perturbations to the width of the structure and on the angle between the LOS and the axis of the structure. Sausage modes are always affected negatively from the observational point of view, as the observed amplitude is always less than the actual one. This effect should be taken into account in the interpretation of wave phenomena observed in the corona with space-borne and ground-based imaging telescopes

Transverse waves in a post-flare supra-arcade

Observations of propagating transverse waves in an open magnetic field structure with the Transition Region And Coronal Explorer (TRACE) are presented. Waves associated with dark tadpole-like sunward moving structures in the post-flare supra-arcade of NOAA active region 9906 on the 21st of April 2002 are analysed. They are seen as quasi-periodic transverse displacements of the dark tadpole tails, with periods in the range of 90–220 s. Their phase speeds and displacement amplitudes decrease as they propagate sunwards. At heights of 90 and 60 Mm above the post-flare loop footpoints the phase speeds are in the ranges 200–700 km s −1 and 90–200 km s −1 respectively. Furthermore, for consecutive tadpoles the phase speeds decrease and periods increase as a function of time. The waves are interpreted as propagating fast magnetoacoustic kink waves guided by a vertical, evolving, open structure

Draft genome sequence of the naturally competent Bacillus simplex strain WY10

ABSTRACT We sequenced a naturally competent bacterial isolate, WY10, cultured from a Wyoming soil sample. Sequence analysis revealed that WY10 is a novel strain of Bacillus simplex . To our knowledge, WY10 is the first B. simplex strain to be characterized as naturally competent for DNA uptake by transformation. </jats:p

Hadronic and radiative three-body decays of J/psi involving the scalars f0(1370), f0(1500) and f0(1710)

We study the role of the scalar resonances f0(1370), f0(1500) and f0(1710) in the strong and radiative three-body decays of J/psi with J/psi to V + P P (gamma gamma) and J/psi to gamma + P P (V V), where P (V) denotes a pseudoscalar (vector) meson. We assume that the scalars result from a glueball-quarkonium mixing scheme while the dynamics of the transition process is described in an effective chiral Lagrangian approach. Present data on J/psi to V + P P are well reproduced, predictions for the radiative processes serve as further tests of this scenario.Comment: 15 page

Lepton flavor violating decays of vector mesons

We estimate the rates of lepton flavor violating decays of the vector mesons $\rho, \omega, \phi \to e \mu$. The theoretical tools are based on an effective Lagrangian approach without referring to any specific realization of the physics beyond the standard model responsible for lepton flavor violation (\Lfv). The effective lepton-vector meson couplings are extracted from the existing experimental bounds on the nuclear $\mu^--e^-$ conversion. In particular, we derive an upper limit for the \Lfv branching ratio ${\rm Br}(\phi \to e \mu) \leq1.3 \times 10^{-21}$ which is much more stringent than the recent experimental result ${\rm Br}(\phi \to e \mu) < 2 \times 10^{-6}$ presented by the SND Collaboration. Very tiny limits on \Lfv decays of vector mesons derived in this letter make direct experimental observation of these processes unrealistic.Comment: 3 pages, 1 figure, accepted for publication in Phys. Rev.

Fast magnetoacoustic waves in curved coronal loops. II, Tunneling modes

Aims. Fast magnetoacoustic waves in curved coronal loops are investigated and the role of lateral leakage in wave damping, which includes the mechanism of wave tunneling, is explored. Methods. A coronal loop is modeled as a curved, magnetic slab in the zero plasma-β limit. In this model and for an arbitrary piece-wise continuous power law equilibrium density profile, the wave equation governing linear vertically polarised fast magnetoacoustic waves is solved analytically. An associated dispersion relation is derived and the frequencies and eigenfunctions of the wave modes are characterised. Results. For some equilibria, the waves are shown to be all damped due to lateral leakage. It is demonstrated that waves either leak straight out into the external medium or have to overcome an evanescent barrier, which is linked to wave tunneling. The wave solutions consist of alternating vertically polarised kink and sausage branches. Fast kink oscillations may have a non-zero density perturbation when averaged across the loop. The calculated damping rate of fast magnetoacoustic kink oscillations is shown to be consistent with related numerical simulations and show that lateral leakage may explain the observed damping of (vertically polarised) fast magnetoacoustic kink oscillations

Quasi-periodic pulsations in the gamma-ray emission of a solar flare

Quasi-periodic pulsations (QPPs) of gamma-ray emission with a period of about 40 s are found in a single loop X-class solar flare on 2005 January 1 at photon energies up to 2-6 MeV with the SOlar Neutrons and Gamma-rays (SONG) experiment aboard the CORONAS-F mission. The oscillations are also found to be present in the microwave emission detected with the Nobeyama Radioheliograph, and in the hard X-ray and low energy gamma-ray channels of RHESSI. Periodogram and correlation analysis shows that the 40 s QPPs of microwave, hard X-ray, and gamma-ray emission are almost synchronous in all observation bands. Analysis of the spatial structure of hard X-ray and low energy (80-225 keV) gamma-ray QPP with RHESSI reveals synchronous while asymmetric QPP at both footpoints of the flaring loop. The difference between the averaged hard X-ray fluxes coming from the two footpoint sources is found to oscillate with a period of about 13 s for five cycles in the highest emission stage of the flare. The proposed mechanism generating the 40 s QPP is a triggering of magnetic reconnection by a kink oscillation in a nearby loop. The 13 s periodicity could be produced by the second harmonics of the sausage mode of the flaring loop

New bounds on lepton flavor violating decays of vector mesons and the Z0 boson

We give an estimate for the upper bounds on rates of lepton flavor violating (LFV) decays M to mu(pm) + e(mp) of vector mesons M = rho0, omega, phi, J/psi, Upsilon and the Z0 boson in a model independent way, analyzing the corresponding lowest dimension effective operators. These operators also contribute to nuclear mu-e-conversion. Based on this observation and using the existing experimental limits on this LFV nuclear process, we show that the studied two-body LFV decays of vector bosons are strongly suppressed independent on the explicit realization of new physics. The upper limits on the rates of some of these decays are significantly more stringent than similar limits known in the literature. In view of these results experimental observation of the two-body LFV decays of vector bosons looks presently unrealistic.Comment: 4 pages, 1 figur

Narrowband spectroscopy by all-optical correlation of broadband pulses

High peak power ultrafast lasers are widely used in nonlinear spectroscopy but often limit its spectral resolution because of the broad frequency bandwidth of ultrashort laser pulses. Improving the resolution by achieving spectrally narrow excitation of, or emission from, the resonant medium by means of multi-photon interferences has been the focus of many recent developments in ultrafast spectroscopy. We demonstrate an alternative approach, in which high resolution is exercised by detecting narrow spectral correlations between broadband excitation and emission optical fields. All-optical correlation analysis, easily incorporated into the traditional spectroscopic setup, enables direct, robust and simultaneous detection of multiple narrow resonances with a single femtosecond pulse.Comment: 5 pages, 4 figures, submitted to PR