Experiment Luxembourg

The earlier orbits and ephemerides for the Soviet satellites were not sufficiently accurate to be very useful in making observations in Alaska. Extrapolations from our own observations gave better predictions. This merely pointed out the fact that rough observations of meridian transits at high latitudes will give better values of the inclination of the orbit than precision observations at low latitudes. Hence, it was decided to observe visually the meridian transits estimating the altitude by noting the position with respect to the stars or using crude alidade measurements. The times of the earlier observations were observed on a watch or clock and the clock correction obtained from WWV. Later the times were determined with the aid of stop watches, taking time intervals from WWV signals. This rather meager program of optical observations of the Soviet satellites was undertaken to give supplementary data for use of the radio observations, and particularly to assist in the prediction of position of the satellite so that the 61-foot radar of Stanford Research Institute could be set accurately enough to observe it (the beam width at the half-power points is about 3°). This report contains primarily the visual observations made at the Geophysical Institute by various members of the staff, and a series of observations by Olaf Halverson at Nome, Alaska. In addition there is a short discussion of the geometry of the trajectory, the illumination of a circumpolar satellite, and a note on the evaluation of Brouwer's moment factors.The research reported In this document has been sponsored by the Geophysics Research Directorate of the Air Force Cambridge Research Center* Air Research and Development Command, under Contract AF 19(604)-3880.List of Figures -- Introduction -- Present knowledge of the electron densities and collision frequencies in the D region of the ionosphere. -- The theory of radio wave interaction. -- The outline of the planned experiment. -- Some comments about the planned experiment. Some comments about gyrointeraction. -- Conclusion -- Acknowledgements -- ReferencesYe

Isospin Mixing of Narrow Pentaquark States

Interpreting the recently discovered narrow exotic baryons as pentaquark states, we discuss, along an old argument of ours, the isospin mixing occurring within the two doublets of $Q = -1$ and Q=0 states lying inside the $S=-2$ ($\Xi$-cascade) sector. We argue that, at least within the Jaffe-Wilczek assignment, presently available data already indicate that mixing should occur at an observable level in both charge sectors, with mixing angles that can be predicted in terms of ratios of observable mass splittings.Comment: 11 pages, 2 figures, to be submitted to PL

On the Top Mass Reconstruction Using Leptons

I discuss the feasibility of measuring the top quark mass by the using of final states with leptons and J/\psi at hadron colliders. I also investigate the impact of matrix-element corrections to the HERWIG simulation of top decays.Comment: 4 pages, 3 figures. Talk given at the UK Phenomenology Workshop on Collider Physics, Durham, U. K., 19-24 September 1999. Revised version with updated result

Elementary excitation families and their frequency ordering in cylindrically symmetric Bose-Einstein condensates

We present a systematic classification of the elementary excitations of Bose-Einstein condensates in cylindrical traps in terms of their shapes. The classification generalizes the concept of families of excitations first identified by Hutchinson and Zaremba (1998) Phys. Rev. A 57 1280 by introducing a second classification number that allows all possible modes to be assigned to a family. We relate the energy ordering of the modes to their family classification, and provide a simple model which explains the relationship.Comment: 15 pages, 8 figures; abstract complemented, section 4.2 shortened, references corrected; to be published in J. Phys.

Detection of the radial velocity curve of the B5-A0 supergiant companion star of Cir X-1?

In this Paper we report on phase resolved I-band optical spectroscopic and photometric observations of CirX-1 obtained with the Very Large Telescope. The spectra are dominated by Paschen absorption lines at nearly all orbital phases except near phase zero (coinciding with the X-ray dip) when the absorption lines are filled-in by broad Paschen emission lines. The radial velocity curve of the absorption lines corresponds to an eccentric orbit (e=0.45) whose period and time of periastron passage are consistent with the period and phase predicted by the most recent X-ray dip ephemeris. We found that the I-band magnitude decreases from 17.6 to ~16.8 near phase 0.9-1.0, this brightening coincides in phase with the X-ray dip. Even though it is likely that the absorption line spectrum is associated with the companion star of CirX-1, we cannot exclude the possibility that the spectrum originates in the accretion disc. However, if the spectrum belongs to the companion star, it must be a supergiant of spectral type B5-A0. If we assume that the compact object does not move through the companion star at periastron, the companion star mass is constrained to ~<10 Msun for a 1.4 Msun neutron star, whereas the inclination has to be ~> 13.7 degrees. Alternatively, the measured absorption lines and their radial velocity curve can be associated with the accretion disc surrounding a 1.4 Msun neutron star and its motion around the centre of mass. An absorption line spectrum from an accretion disc is typically found when our line-of-sight passes through the accretion disc rim implying a high inclination. However, from radio observations it was found that the angle between the line-of-sight and the jet axis is smaller than 5 degrees implying that the jet ploughs through the accretion disc in this scenario.Comment: 8 pages, 4 figures, 3 tables, accepted by MNRA

F-Term Hybrid Inflation Followed by a Peccei-Quinn Phase Transition

We consider a cosmological set-up, based on renormalizable superpotential terms, in which a superheavy scale F-term hybrid inflation is followed by a Peccei-Quinn phase transition, resolving the strong CP and mu problems of the minimal supersymmetric standard model. We show that the field which triggers the Peccei-Quinn phase transition can remain after inflation well above the Peccei-Quinn scale thanks to (i) its participation in the supergravity and logarithmic corrections during the inflationary stage and (ii) the high reheat temperature after the same period. As a consequence, its presence influences drastically the inflationary dynamics and the universe suffers a second period of reheating after the Peccei-Quinn phase transition. Confronting our inflationary predictions with the current observational data, we find that, for about the central value of the spectral index, the grand unification scale can be identified with its supersymmetric value for the relevant coupling constant \kappa=0.002 and, more or less, natural values, +/-(0.01-0.1), for the remaining parameters. On the other hand, the final reheat temeperature after the Peccei-Quinn phase transition turns out to be low enough so as the gravitino problem is avoided.Comment: 15 pages including 8 figures, version published in Phys. Rev.

Deduction of the quantum numbers of low-lying states of 6-nucleon systems based on symmetry

The inherent nodal structures of the wavefunctions of 6-nucleon systems have been investigated. The existence of a group of six low-lying states dominated by L=0 has been deduced. The spatial symmetries of these six states are found to be mainly {4,2} and {2,2,2}.Comment: 8 pages, no figure