34,923 research outputs found
Effect of hybridization on the magnetic properties of correlated two-band metals
The magnetic properties of transition-like metals are discussed within the
single site approximation, which is a picture to take into account electron
correlations. The metal is described by two hybridized bands one of which
includes Coulomb correlation. The presented results indicate that
ferromagnetism arises for adequate values of hybridization (V), correlation (U)
and occupation number(). Some similarities with Dynamical
Mean-Field Theory (DMFT) are indicated.Comment: 3 pages, 3 figures, presented at the 53rd MMM08 conference in Austin,
200
Electroweak corrections to e+ e- -> nu anti-nu H and e+ e- -> t anti-t H
The most interesting Higgs-production processes at future e+ e- colliders
belong to the process class e+ e- -> f anti-f H. We study the full O(alpha)
corrections to this reaction in the Standard Model for neutrinos and top quarks
in the final state. Leading higher-order corrections from initial-state
radiation and QCD corrections are also taken into account. Although
cancellations between the different kinds of corrections occur, the full
corrections are of the order of +/-10% and thus important ingredients in the
theoretical predictions for future e+ e- colliders.Comment: 3 pages, LaTeX, 4 postscript figures, talk given at the EPS
conference, Aachen, 200
Electroweak radiative corrections to e+ e- -> t anti-t H
We have calculated the complete electroweak O(alpha) radiative corrections to
the Higgs-boson production process e+ e- -> t anti-t H in the electroweak
Standard Model. Initial-state radiation beyond O(alpha) is included in the
structure-function approach. The calculation of the corrections is briefly
described, and numerical results are presented for the total cross section.
Both the photonic and the genuine weak corrections reach the order of about 10%
or even more and show a non-trivial dependence on the Higgs-boson mass and on
the scattering energy. We compare our results with two previous calculations
that obtained differing results at high energies.Comment: 13 pages, LaTeX, 12 postscript figure
Science Verification Results from PMAS
PMAS, the Potsdam Multi-Aperture Spectrophotometer, is a new integral field
instrument which was commissioned at the Calar Alto 3.5m Telescope in May 2001.
We report on results obtained from a science verification run in October 2001.
We present observations of the low-metallicity blue compact dwarf galaxy
SBS0335-052, the ultra-luminous X-ray Source X-1 in the Holmberg II galaxy, the
quadruple gravitational lens system Q2237+0305 (the "Einstein Cross"), the
Galactic planetary nebula NGC7027, and extragalactic planetary nebulae in M31.
PMAS is now available as a common user instrument at Calar Alto Observatory.Comment: 4 pages, 9 figures (attached in JPEG format), Euro3D Science Workshop
Proceedings, held in Cambridge May 21-23, 2003, to appear in AN (accepted
Vibration
Physiological and biomechanical responses of humans to vibrations during manned space flight and threshold data on tolerances to various vibrational modes and condition
Thermal environment
Human tolerance in thermal environment, thermal physiology of space clothing, and biothermal considerations in space cabin desig
Electroweak Precision Physics at e+ e- Colliders with RacoonWW
We present precise predictions for the processes e+ e- -> WW -> 4f(gamma) at
LEP2 and future Linear-Collider (LC) energies obtained with the Monte Carlo
generator RacoonWW. The program RacoonWW includes the complete O(alpha)
electroweak radiative corrections to e+ e- -> WW -> 4f in the double-pole
approximation (DPA). While the virtual corrections are treated in DPA, the
calculation of the bremsstrahlung corrections is based on the full lowest-order
matrix elements to the processes e+ e- -> 4f+gamma. This asymmetric treatment
of virtual and real photons requires a careful matching of the arising infrared
and collinear singularities. We also take into account higher-order
initial-state photon radiation via the structure-function method. Here, we
briefly describe the RacoonWW approach, give numerical results for the total
W-pair production cross sections, confront them with LEP2 data, and study the
impact of the radiative corrections on angular and W-invariant-mass
distributions at LEP2 and LC energies.Comment: 12 pages, 13 postscript figures, to appear in the Proceedings of the
22nd annual MRST Conference on Theoretical High Energy Physics (MRST 2000),
Rochester, New York, May 8-9, 200
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