3,721 research outputs found
R-matrix calculation of differential cross sections for low-energy electron collisions with ground and electronically excited state O2 molecules
Differential cross sections for electron collisions with the O molecule
in its ground state, as well as excited
and states are calculated. As previously, the fixed-bond
R-matrix method based on state-averaged complete active space SCF orbitals is
employed. In additions to elastic scattering of electron with the O
, and states, electron
impact excitation from the state to the
and states as well as '6 eV states' of
, and states is
studied. Differential cross sections for excitation to the '6 eV states' have
not been calculated previously. Electron impact excitation to the
state from the metastable state is also
studied. For electron impact excitation from the O
state to the state, our results agree better with the
experimental measurements than previous theoretical calculations. Our cross
sections show angular behaviour similar to the experimental ones for
transitions from the state to the '6 eV states', although
the calculated cross sections are up to a factor two larger at large scattering
angles. For the excitation from the state to the
state, our results marginally agree with the experimental
data except for the forward scattering direction
Interaction of massless Dirac field with a Poincar\'e gauge field
In this paper we consider a model of Poincar\'e gauge theory (PGT) in which a
translational gauge field and a Lorentz gauge field are actually identified
with the Einstein's gravitational field and a pair of ``Yang-Mills'' field and
its partner, respectively.In this model we re-derive some special solutions and
take up one of them. The solution represents a ``Yang-Mills'' field without its
partner field and the Reissner-Nordstr\"om type spacetime, which are generated
by a PGT-gauge charge and its mass.It is main purpose of this paper to
investigate the interaction of massless Dirac fields with those fields. As a
result, we find an interesting fact that the left-handed massless Dirac fields
behave in the different manner from the right-handed ones. This can be
explained as to be caused by the direct interaction of Dirac fields with the
``Yang-Mills'' field. Accordingly, the phenomenon can not happen in the
behavior of the neutrino waves in ordinary Reissner-Nordstr\"om geometry. The
difference between left- and right-handed effects is calculated quantitatively,
considering the scattering problems of the massless Dirac fields by our
Reissner-Nordstr\"om type black-hole.Comment: 10pages, RevTeX3.
Effects of Geological Heterogenetiy in Watershed Area on Sediment Distribution and Benthic Macroinvertebrate Community in River System
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv
Leading Effects in Hadroproductions of Lambda_c and D From Constituent Quark-Diquark Cascade Picture
We discuss the hadroproductions of Lambda_c, Lambda_c bar, D and D bar in the
framework of the constituent quark-diquark cascade model taking into account
the valence quark annihilation. The spectra of Lambda_c and Lambda_c bar in pA,
Sigma^-A and pi^-A collisions are well explained by the model using the values
of parameters used in hadroproductions of D and D bar. It is shown that the
role of valence diquark in the incident baryon is important for D bar
productions as well as for Lambda_c production.Comment: 11 pages, 5 figures, v2:some explanations added, references added,
typos corrected, v3: top margin change
Nonlinear Evolution of Cosmic Magnetic Fields and Cosmic Microwave Background Anisotropies
In this work we investigate the effects of the primordial magnetic fields on
cosmic microwave background anisotropies (CMB). Based on cosmological
magnetohydrodynamic (MHD) simulations we calculate the CMB anisotropy spectra
and polarization induced by fluid fluctuations (Alfv\'en modes) generated by
primordial magnetic fields. The strongest effect on the CMB spectra comes from
the transition epoch from a turbulent regime to a viscous regime. The balance
between magnetic and kinetic energy until the onset of the viscous regime
provides a one to one relation between the comoving coherence length and
the comoving magnetic field strength , such as . The resulting CMB temperature and polarization anisotropies are
somewhat different from the ones previously obtained by using linear
perturbation theory. Our calculation gives a constraint on the magnetic field
strength in the intermediate scale of CMB observations. Upper limits are set by
WMAP and BOOMERANG results for comoving magnetic field strength of with a comoving coherence length of for the most extreme
case, or for the most conservative case.Comment: accepted for publication in Phys. Rev.
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