1,390,389 research outputs found
General study of superscaling in quasielastic and reactions using the relativistic impulse approximation
The phenomenon of superscaling for quasielastic lepton induced reactions at
energies of a few GeV is investigated within the framework of the relativistic
impulse approximation. A global analysis of quasielastic inclusive electron and
charged-current neutrino scattering reactions on nuclei is presented. Scaling
and superscaling properties are shown to emerge from both types of processes.
The crucial role played by final state interactions is evaluated by using
different approaches. The asymmetric shape presented by the experimental
scaling function, with a long tail in the region of positive values of the
scaling variable, is reproduced when the interaction in the final state between
the knockout nucleon and the residual nucleus is described within the
relativistic mean field approach. The impact of gauge ambiguities and off-shell
effects in the scaling function is also analyzed.Comment: 34 pages, 14 figures, accepted in Phys. Rev. C. Section II has been
shortene
Holddown arm release mechanism used on Saturn vehicles
With the development of the Saturn launch vehicle, it became mandatory to develop a system for restraining the vehicle until after all checks and engine thrust buildup were completed. The basic Saturn I holddown arm constrains the vehicle by clamping it between a fixed support and a movable jaw. The jaw is on a link pinned to rotate sufficiently to release the vehicle. There are three links in the jaw (restraining) system arranged so that with a small force provided by a pneumatic separator mechanism, the large loads of the vehicle can be restrained. Design details discussed are the link system, the separator, adjustments, and the energy absorber. The function of preloading is discussed. The secondary release system is described. Finally, the design differences between the Saturn I and the Saturn V arm are described
NLO Leptoquark Production and Decay: The Narrow-Width Approximation and Beyond
We study the leptoquark model of Buchm\"uller, R\"uckl and Wyler, focusing on
a particular type of scalar () and vector () leptoquark. The primary
aim is to perform the calculations for leptoquark production and decay at
next-to-leading order (NLO) to establish the importance of the NLO
contributions and, in particular, to determine how effective the
narrow-width-approximation (NWA) is at NLO. For both the scalar and vector
leptoquarks it is found that the NLO contributions are large, with the larger
corrections occurring for the case vector leptoquarks. For the scalar
leptoquark it is found that the NWA provides a good approximation for
determining the resonant peak, however the NWA is not as effective for the
vector leptoquark. For both the scalar and vector leptoquarks there are large
contributions away from the resonant peak, which are missing from the NWA
results, and these make a significant difference to the total cross-section.Comment: 22 pages, 17 figure
Influence of Strip-Mining on the Mortality of a Wetland Caddisfly, \u3ci\u3eLimnephilus Indivisus\u3c/i\u3e (Trichoptera: Limnephilidae).
A coal mine about 2.2 km upstream from Stillfork Swamp Nature Preserve, Carroll Co., Ohio was suspected of causing a reduction in Limnephilus indivisus caddisflies in the south half of the preserve. Second instar L. indivisus larvae collected from the south half of the preserve and from two control areas were reared in cages at the site of collection and at the other two sites in a replicated experiment. Elevated total dissolved solids in water samples from within rearing enclosures displayed strong correlation (r2 = 0.864) with increased mortality when compared to larvae reared in unaffected areas. This investigation suggests that larvae of L. indivisus are useful in biomonitoring of wetlands impacted by acid-mine drainage, and potentially other perturbations
Phase transition from quark-meson coupling hyperonic matter to deconfined quark matter
We investigate the possibility and consequences of phase transitions from an
equation of state (EOS) describing nucleons and hyperons interacting via mean
fields of sigma, omega, and rho mesons in the recently improved quark-meson
coupling (QMC) model to an EOS describing a Fermi gas of quarks in an MIT bag.
The transition to a mixed phase of baryons and deconfined quarks, and
subsequently to a pure deconfined quark phase, is described using the method of
Glendenning. The overall EOS for the three phases is calculated for various
scenarios and used to calculate stellar solutions using the
Tolman-Oppenheimer-Volkoff equations. The results are compared with recent
experimental data, and the validity of each case is discussed with consequences
for determining the species content of the interior of neutron stars.Comment: 12 pages, 14 figures; minor typos correcte
Origin of ferromagnetism in CsAgF: importance of Ag - F covalency
The magnetic nature of CsAgF, an isoelectronic and isostructural
analogue of LaCuO, is analyzed using density functional calculations.
The ground state is found to be ferromagnetic and nearly half metallic. We find
strong hybridization of Ag- and F- states. Substantial moments reside on
the F atoms, which is unusual for the halides and reflects the chemistry of the
Ag(II) ions in this compound. This provides the mechanism for ferromagnetism,
which we find to be itinerant in character, a result of a Stoner instability
enhanced by Hund's coupling on the F
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