1,944,873 research outputs found
X-Ray Timing, Spectroscopy and Photometry of the Anomalous X-Ray Pulsar Candidate CXOU J010043.1-721134
We present new X-ray timing and spectral results on the 8.0-second X-ray
pulsar CXOU J010043.1-721134 from a series of observations using the Chandra
X-ray Observatory. We find a spin period in 2004 January of 8.020392pm0.000009
seconds. Comparison of this to 2001 Chandra observations implies a period
derivative dot{P} = (1.88 pm 0.08) times 10^{-11} s s^{-1}, leading to an
inferred dipole surface magnetic field of 3.9 times 10^{14} G. The spectrum is
well fit to an absorbed blackbody of temperature kT = 0.38pm0.02 keV with a
power law tail of photon index Gamma = 2.0pm0.6. We find that the source has an
unabsorbed X-ray flux (0.5-10 keV) of 4(+2-1) times 10^{-13} erg cm^{-2} s^{-1}
and a corresponding X-ray luminosity of ~2 times 10^{35} erg s^{-1} for a
distance of 60 kpc. These properties support classification of CXOU
J010043.1-721134 as the seventh confirmed anomalous X-ray pulsar,the eleventh
confirmed magnetar, and the first magnetar to be identified in the Small
Magellanic Cloud.Comment: 5 pages, plus 1 embedded eps figure. Refined coordinates of source,
including typo in declination. ApJ Letters, in pres
Pionic transitions from X(3872) to chi_{cJ}
We consider transitions from the resonance X(3872) to the chi_{cJ} states of
charmonium with emission of one or two pions as a means of studying the
structure of the X resonance. We find that the relative rates for these
transitions to the final states with different J significantly depend on
whether the initial state is a pure charmonium state or a four-quark/molecular
state.Comment: 12 page
Comment on "Summing One-Loop Graphs at Multi-Particle Threshold"
The propagator of a virtual -field with emission of on-mass-shell
particles all being exactly at rest is calculated at the tree-level in theory by directly solving recursion equations for the sum of Feynman
graphs. It is shown that the generating function for these propagators is
equivalent to a Fourier transform of the recently found Green's function within
the background-field technique for summing graphs at threshold suggested by
Lowell Brown. Also the derivation of the result that the tree-level
on-mass-shell scattering amplitudes of the processes are exactly
vanishing at threshold for is thus given in the more conventional
Feynman diagram technique.Comment: 7 pages, LaTeX, TPI-MINN-92/46-
The purity of and challenged
It is suggested that the resonance may contain a sizeable
( in terms of the probability weight factor) four-quark component with
the up- and down- quarks and antiquarks in addition to the pair,
which component in itself has a substantial part with the isospin I=1.
Furthermore such four-quark part of the wave function should also affect the
properties of the charmonium resonance through the
mixing previously considered in the literature. It is argued that an admixture
of extra light quark pairs can explain a possible discrepancy between the
theoretical expectations and the recent data on the non- decay
width of the and the ratio of the yield of charged and neutral
meson pairs in its decays, as well as on the extra rate of the direct
decay into light hadrons and the rate of the decay . It
is further argued that the suggested four-quark component of the wave function
of the should give rise to a measurable rate of the decays
and .Comment: 13 page
Massive liquid Ar and Xe detectors for direct Dark Matter searches
A novel experiment for direct searches of the Dark Matter with liquid argon
double-phase chamber with a mass of liquid Ar up to several hundred tons is
proposed. To suppress the b-, g- and n0- backgrounds, the comparison of
scintillation and ionization signals for every event is suggested. The addition
in liquid Ar of photosensitive Ge(CH3)4 or C2H4 and suppression of triplet
component of scintillation signals ensures the detection of scintillation
signals with high efficiency and provides a complete suppression of the
electron background. For the detection of photoelectrons and ionization
electrons, highly stable and reliable GEM detectors must be used.Comment: 8 pages, 2 figures, 1 tabl
On the Fourier expansion method for highly accurate computation of the Voigt/complex error function in a rapid algorithm
In our recent publication [1] we presented an exponential series
approximation suitable for highly accurate computation of the complex error
function in a rapid algorithm. In this Short Communication we describe how a
simplified representation of the proposed complex error function approximation
makes possible further algorithmic optimization resulting in a considerable
computational acceleration without compromise on accuracy.Comment: 4 page
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