145,403 research outputs found
Norm resolvent convergence of singularly scaled Schr\"odinger operators and \delta'-potentials
For a real-valued function V from the Faddeev-Marchenko class, we prove the
norm resolvent convergence, as \epsilon goes to 0, of a family S_\epsilon of
one-dimensional Schr\"odinger operators on the line of the form S_\epsilon:=
-D^2 + \epsilon^{-2} V(x/\epsilon). Under certain conditions the family of
potentials converges in the sense of distributions to the first derivative of
the Dirac delta-function, and then the limit of S_\epsilon might be considered
as a "physically motivated" interpretation of the one-dimensional Schr\"odinger
operator with potential \delta'.Comment: 30 pages, 2 figure; submitted to Proceedings of the Royal Society of
Edinburg
Diffractive meson production from virtual photons with odd charge-parity exchange
We calculate the cross section of diffractive charge-parity C=+1 neutral
meson production in virtual photon proton collision at high energies. Due to
the opposite C-parities of photon and meson M (M = eta_C, pi^0, a_2) this
process probes the t-channel C=-1 odderon exchange which is described here as
noninteracting three-gluon exchange. Estimates for the cross section of the
inelastic diffractive process gamma^* p -> eta_C X_p are presented. The total
cross section of diffractive \eta_C meson photoproduction is found to be 47 pb.
The cross sections for the diffractive production of light mesons (pi^0, a_2)
in \gamma^* p collisions are of the same order if the photon virtuality Q^2 is
m^2_C.Comment: LaTeX, 19 pages, 8 ps-figs, epsfi
Physics of Interpulse Emission in Radio Pulsars
The magnetized induced Compton scattering off the particles of the
ultrarelativistic electron-positron plasma of pulsar is considered. The main
attention is paid to the transverse regime of the scattering, which holds in a
moderately strong magnetic field. We specifically examine the problem on
induced transverse scattering of the radio beam into the background, which
takes place in the open field line tube of a pulsar. In this case, the
radiation is predominantly scattered backwards and the scattered component may
grow considerably. Based on this effect, we for the first time suggest a
physical explanation of the interpulse emission observed in the profiles of
some pulsars. Our model can naturally account for the peculiar spectral and
polarization properties of the interpulses. Furthermore, it implies a specific
connection of the interpulse to the main pulse, which may reveal itself in the
consistent intensity fluctuations of the components at different timescales.
Diverse observational manifestations of this connection, including the moding
behavior of PSR B1822-09, the peculiar temporal and frequency structure of the
giant interpulses in the Crab pulsar, and the intrinsic phase correspondence of
the subpulse patterns in the main pulse and the interpulse of PSR B1702-19, are
discussed in detail. It is also argued that the pulse-to-pulse fluctuations of
the scattering efficiency may lead to strong variability of the interpulse,
which is yet to be studied observationally. In particular, some pulsars may
exhibit transient interpulses, i.e. the scattered component may be detectable
only occasionally.Comment: 28 pages, 2 figures. Accepted for publication in Ap
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