2,636,645 research outputs found
The dynamical equation of the spinning electron
We obtain by invariance arguments the relativistic and non-relativistic
invariant dynamical equations of a classical model of a spinning electron. We
apply the formalism to a particular classical model which satisfies Dirac's
equation when quantised. It is shown that the dynamics can be described in
terms of the evolution of the point charge which satisfies a fourth order
differential equation or, alternatively, as a system of second order
differential equations by describing the evolution of both the center of mass
and center of charge of the particle. As an application of the found dynamical
equations, the Coulomb interaction between two spinning electrons is
considered. We find from the classical viewpoint that these spinning electrons
can form bound states under suitable initial conditions. Since the classical
Coulomb interaction of two spinless point electrons does not allow for the
existence of bound states, it is the spin structure that gives rise to new
physical phenomena not described in the spinless case. Perhaps the paper may be
interesting from the mathematical point of view but not from the point of view
of physics.Comment: Latex2e, 14 pages, 5 figure
The mass function of GX 339-4 from spectroscopic observations of its donor star
We obtained 16 VLT/X-shooter observations of GX 339-4 in quiescence in the
period May - September 2016 and detected absorption lines from the donor star
in its NIR spectrum. This allows us to measure the radial velocity curve and
projected rotational velocity of the donor for the first time. We confirm the
1.76 day orbital period and we find that = km s,
km s and km s. From
these values we compute a mass function , a
factor lower than previously reported, and a mass ratio . We confirm the donor is a K-type star and estimate that it contributes
of the light in the - and H-band. We constrain the binary
inclination to and the black hole mass to
. GX 339-4 may therefore be the
first black hole to fall in the 'mass-gap' of .Comment: 11 pages, 7 figures, accepted for publication in Ap
Discovery of X-ray Jets in the Microquasar H 1743-322
We report on the formation and evolution of two large-scale,
synchrotron-emitting jets from the black hole candidate H 1743-322 following
its reactivation in 2003. In November 2003 after the end of its 2003 outburst,
we noticed, in observations with the Australia Telescope Compact Array, the
presence of a new and variable radio source about 4.6" to the East of H
1743-322, that was later found to move away from H 1743-322. In February 2004,
we detected a radio source to the West of H 1743-322, symmetrically placed
relative to the Eastern jet. In 2004, follow-up X-ray observations with {\em
Chandra} led to the discovery of X-ray emission associated with the two radio
sources. This likely indicates that we are witnessing the interaction of
relativistic jets from H 1743-322 with the interstellar medium causing in-situ
particle acceleration. The spectral energy distribution of the jets during the
decay phase is consistent with a classical synchrotron spectrum of a single
electron distribution from radio up to X-rays, implying the production of very
high energy ( 10 TeV) particles in those jets. We discuss the jet
kinematics, highlighting the presence of a significantly relativistic flow in H
1743-322 almost a year after the ejection event.Comment: Accepted for publication in The Astrophysical Journal. 17 pages, 9
figure
Dirac equation for membranes
Dirac's idea of taking the square root of constraints is applied to the case
of extended objects concentrating on membranes in D=4 space-time dimensions.
The resulting equation is Lorentz invariant and predicts an infinite hierarchy
of positive and negative masses (tension). There are no tachyonic solutions.Comment: 5 pages, 1 figure, v2: improved version, accepted for publication as
a Brief Report in Physical Review
Stirling cycle cryogenic cooler
A long lifetime Stirling cycle cryogenic cooler particularly adapted for space applications is described. It consists of a compressor section centrally aligned end to end with an expansion section, and respectively includes a reciprocating compressor piston and displacer radially suspended in interconnecting cylindrical housings by active magnetic bearings and has adjacent reduced clearance regions so as to be in noncontacting relationship therewith and wherein one or more of these regions operate as clearance seals. The piston and displacer are reciprocated in their housings by linear drive motors to vary the volume of respectively adjacent compression and expansion spaces which contain a gaseous working fluid and a thermal regenerator to effect Stirling cycle cryogenic cooling
Electromagnetism and multiple-valued loop-dependent wave functionals
We quantize the Maxwell theory in the presence of a electric charge in a
"dual" Loop Representation, i.e. a geometric representation of magnetic
Faraday's lines. It is found that the theory can be seen as a theory without
sources, except by the fact that the wave functional becomes multivalued. This
can be seen as the dual counterpart of what occurs in Maxwell theory with a
magnetic pole, when it is quantized in the ordinary Loop Representation. The
multivaluedness can be seen as a result of the multiply-connectedness of the
configuration space of the quantum theory.Comment: 5 page
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