32,873 research outputs found
Lost City meteorite: Its recovery and a comparison with other fireballs
Lost City meteoroid trajectory analysis and determination of original mas
Lost City meteorite - It's recovery and a comparison with other fireballs
Photographic and trajectory data for Lost City meteor and establishment of calibration of mass scale of other meteor
Vacuum state of the quantum string without anomalies in any number of dimensions
We show that the anomalies of the Virasoro algebra are due to the asymmetric
behavior of raising and lowering operators with respect to the ground state of
the string. With the adoption of a symmetric vacuum we obtain a non-anomalous
theory in any number of dimensions. In particular for D=4.Comment: 14 pages, LaTex, no figure
Electron Self Energy for Higher Excited S Levels
A nonperturbative numerical evaluation of the one-photon electron self energy
for the 3S and 4S states with charge numbers Z=1 to 5 is described. The
numerical results are in agreement with known terms in the expansion of the
self energy in powers of Zalpha.Comment: 3 pages, RevTeX, to appear in Phys. Rev.
Generalized Supersymmetric Perturbation Theory
Using the basic ingredient of supersymmetry, we develop a simple alternative
approach to perturbation theory in one-dimensional non-relativistic quantum
mechanics. The formulae for the energy shifts and wave functions do not involve
tedious calculations which appear in the available perturbation theories. The
model applicable in the same form to both the ground state and excited bound
states, unlike the recently introduced supersymmetric perturbation technique
which, together with other approaches based on logarithmic perturbation theory,
are involved within the more general framework of the present formalism.Comment: 13 pages article in LaTEX (uses standard article.sty). No Figures.
Sent to Ann. Physics (2004
About Superluminal motions and Special Relativity: A Discussion of some recent Experiments, and the solution of the Causal Paradoxes
Some experiments, performed at Berkeley, Cologne, Florence, Vienna, Orsay,
Rennes, etc., led to the claim that something seems to travel with a group
velocity larger than the speed c of light in vacuum. Various other experimental
results seem to point in the same direction: For instance, localized wavelet-
type solutions to Maxwell equations have been found, both theoretically and
experimentally, that travel with superluminal speed. [Even muonic and
electronic neutrinos [it has been proposed] might be "tachyons", since their
square mass appears to be negative]. With regard to the first-mentioned
experiments, it was recently claimed by Guenter Nimtz that those results with
evanescent waves (or tunneling photons) imply superluminal signal and impulse
transmission, and therefore violate Einstein causality. In this note we want to
stress that, on the contrary, all such results do not place relativistic
causality in jeopardy, even if they referred to actual tachyonic motions: In
fact, Special Relativity can cope even with superluminal objects and waves. For
instance, it is possible (at least in microphysics) to solve also the known
causal paradoxes, devised for faster than light motion, although this is not
widely recognized yet. Here we show, in detail and rigorously, how to solve the
oldest causal paradox, originally proposed by Tolman, which is the kernel of
many further tachyon paradoxes (like J.Bell's, F.A.E.Pirani's, J.D.Edmonds' and
others'). The key to the solution is a careful application of tachyon
mechanics, as it unambiguously follows from special relativity. At Last, in one
of the two Appendices, we propose how to evaluate the group-velocity in the
case of evanescent waves. [PACS nos.: 03.30.+p; 03.50.De; 41.20.Jb; 73.40.Gk;
84.40.Az; 42.82.Et ]Comment: LaTeX file: 26 pages, with 5 Figures (and two Appendices). The
original version of this paper appeared in the Journal below
The Induced Magnetic Field of the Moon: Conductivity Profiles and Inferred Temperature
Electromagnetic induction in the moon driven by fluctuations of the interplanetary magnetic field is used to determine the lunar bulk electrical conductivity. The present data clearly show the north-south and east-west transfer function difference as well as high frequency rollover. The difference is shown to be compatible over the mid-frequency range with a noise source associated with the compression of the local remanent field by solar wind dynamic pressure fluctuations. Models for two, three, and four layer; current layer, double current layer, and core plus current layer moons are generated by inversion of the data using a theory which incorporates higher order multipoles. Core radii conductivities generally are in the range 1200 to 1300 km and 0.001 to 0.003 mhos/m; and for the conducting shell 1500 to 1700 km with 0.0001 to 0.0007 mhos/m with an outer layer taken as nonconducting. Core temperature based on available olivine data is 700 to 1000 C
Virial Masses of Black Holes from Single Epoch Spectra of AGN
We describe the general problem of estimating black hole masses of AGN by
calculating the conditional probability distribution of M_BH given some set of
observables. Special attention is given to the case where one uses the AGN
continuum luminosity and emission line widths to estimate M_BH, and we outline
how to set up the conditional probability distribution of M_BH given the
observed luminosity, line width, and redshift. We show how to combine the broad
line estimates of M_BH with information from an intrinsic correlation between
M_BH and L, and from the intrinsic distribution of M_BH, in a manner that
improves the estimates of M_BH. Simulation was used to assess how the
distribution of M_BH inferred from the broad line mass estimates differs from
the intrinsic distribution, and we find that this can lead to an inferred
distribution that is too broad. We use these results and a sample of 25 sources
that have recent reverberation mapping estimates of AGN black hole masses to
investigate the effectiveness of using the C IV emission line to estimate M_BH
and to indirectly probe the C IV region size--luminosity (R--L) relationship.
We estimated M_BH from both C IV and H-Beta for a sample of 100 sources,
including new spectra of 29 quasars. We find that the two emission lines give
consistent estimates if one assumes R \propto L^{1/2}_{UV} for both lines.Comment: 38 pages, 6 figures, accepted by Ap
The nature of the long time decay at a second order transition point
We show that at a second order phase transition, of \phi^4 like system, a
necessary condition for streched exponential decay of the time structure factor
is obeyed. Using the ideas presented in this proof a crude estimate of the
decay of the structure factor is obtained and shown to yield stretched
exponential decay under very reasonable conditions.Comment: 7 page
Random field Ising systems on a general hierarchical lattice: Rigorous inequalities
Random Ising systems on a general hierarchical lattice with both, random
fields and random bonds, are considered. Rigorous inequalities between
eigenvalues of the Jacobian renormalization matrix at the pure fixed point are
obtained. These inequalities lead to upper bounds on the crossover exponents
.Comment: LaTeX, 13 pages, figs. 1a,1b,2. To be published in PR
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