20,506 research outputs found
Analytic approach to nuclear rotational states: The role of spin - A minimal model -
We use a simple field theory model to investigate the role of the nucleon
spin for the magnetic sum rules associated with the low-lying collective
scissors mode in deformed nuclei. Various constraints from rotational symmetry
are elucidated and discussed. We put special emphasis on the coupling of the
spin part of the M1 operator to the low lying collective modes, and investigate
how this coupling changes the sum rules.Comment: 15 pages, 4 figure
Explorer Satellite Electronics
A discussion is presented of the design restrictions and the philosophy which enabled the Explorer satellites to be first during the IGY to reveal the presence of a belt of intense cosmic radiation encircling the earth's equator. In addition, an indication of the amount and momentum of cosmic dust in the solar system was obtained from the Explorers. Methods used to obtain reliability in the transducing and communications system are described, together with interpretations of space-environment information as deduced from the narrow-band telemetry
Convenient Labelling Technique for Mass Spectrometry - Acid Catalyzed Deuterium and Oxygen-18 Exchange via Gas-liquid Chromatography
Mass spectrometry labelling technique - acid catalyzed deuterium and oxygen 18 exchange by gas-liquid chromatograph
Analytical ground state for the three-band Hubbard model
For the calculation of charge excitations as those observed in, e.g.,
photo-emission spectroscopy or in electron-energy loss spectroscopy, a correct
description of ground-state charge properties is essential. In strongly
correlated systems like the undoped cuprates this is a highly non-trivial
problem. In this paper we derive a non-perturbative analytical approximation
for the ground state of the three-band Hubbard model on an infinite, half
filled CuO_2 plane. By comparison with Projector Quantum Monte Carlo
calculations it is shown that the resulting expressions correctly describe the
charge properties of the ground state. Relations to other approaches are
discussed. The analytical ground state preserves size consistency and can be
generalized for other geometries, while still being both easy to interpret and
to evaluate.Comment: REVTeX, 8 pages, 6 figures, to appear in Phys. Rev.
Antiferromagnetic ordering of energy levels for spin ladder with four-spin cyclic exchange: Generalization of the Lieb-Mattis theorem
The Lieb-Mattis theorem is generalized to an antiferromagnetic spin-ladder
model with four-spin cyclic exchange interaction. We prove that for J>2K, the
antiferromagnetic ordering of energy levels takes place separately in two
sectors, which remain symmetric and antisymmetric under the reflection with
respect to the longitudinal axis of the ladder. We prove also that at the
self-dual point J=2K, the Lieb-Mattis rule holds in the sectors with fixed
number of rung singlets. In both cases, it agrees with the similar rule for
Haldane chain with appropriate spin number.Comment: 4 pages, some references updated and added, typos corrected, to
appear in Phys. Rev.
Production of tau tau jj final states at the LHC and the TauSpinner algorithm: the spin-2 case
The TauSpinner algorithm is a tool that allows to modify the physics model of
the Monte Carlo generated samples due to the changed assumptions of event
production dynamics, but without the need of re-generating events. With the
help of weights -lepton production or decay processes can be modified
accordingly to a new physics model. In a recent paper a new version TauSpinner
ver.2.0.0 has been presented which includes a provision for introducing
non-standard states and couplings and study their effects in the
vector-boson-fusion processes by exploiting the spin correlations of
-lepton pair decay products in processes where final states include also
two hard jets. In the present paper we document how this can be achieved taking
as an example the non-standard spin-2 state that couples to Standard Model
particles and tree-level matrix elements with complete helicity information
included for the parton-parton scattering amplitudes into a -lepton pair
and two outgoing partons. This implementation is prepared as the external (user
provided) routine for the TauSpinner algorithm. It exploits amplitudes
generated by MadGraph5 and adopted to the TauSpinner algorithm format.
Consistency tests of the implemented matrix elements, reweighting algorithm and
numerical results for observables sensitive to polarization are
presented.Comment: 17 pages, 6 figures; version published in EPJ
Coupled Cluster Treatment of the Shastry-Sutherland Antiferromagnet
We consider the zero-temperature properties of the spin-half two-dimensional
Shastry-Sutherland antiferromagnet by using a high-order coupled cluster method
(CCM) treatment. We find that this model demonstrates various groundstate
phases (N\'{e}el, magnetically disordered, orthogonal dimer), and we make
predictions for the positions of the phase transition points. In particular, we
find that orthogonal-dimer state becomes the groundstate at . For the critical point where the semi-classical N\'eel
order disappears we obtain a significantly lower value than ,
namely, in the range . We therefore conclude that
an intermediate phase exists between the \Neel and the dimer phases. An
analysis of the energy of a competing spiral phase yields clear evidence that
the spiral phase does not become the groundstate for any value of . The
intermediate phase is therefore magnetically disordered but may exhibit
plaquette or columnar dimer ordering.Comment: 6 pages, 5 figure
- …