74,748 research outputs found
The quantization of the chiral Schwinger model based on the BFT-BFV formalism II
We apply an improved version of Batalin-Fradkin-Tyutin (BFT) Hamiltonian
method to the a=1 chiral Schwinger Model, which is much more nontrivial than
the a>1.\delta\xi$ in the measure. As a result, we explicitly
obtain the fully gauge invariant partition function, which includes a new type
of Wess-Zumino (WZ) term irrelevant to the gauge symmetry as well as usual WZ
action.Comment: 17 pages, To be published in J. Phys.
Deformed two center shell model
A highly specialized two-center shell model has been developed accounting for
the splitting of a deformed parent nucleus into two ellipsoidaly deformed
fragments. The potential is based on deformed oscillator wells in direct
correspondance with the shape change of the nuclear system. For the first time
a potential responsible for the necking part between the fragments is
introduced on potential theory basis. As a direct consequence, spin-orbit {\bf
ls} and {\bf l} operators are calculated as shape dependent. Level scheme
evolution along the fission path for pairs of ellipsoidaly deformed fragments
is calculated. The Strutinsky method yields the shell corrections for different
mass asymmetries from the superheavy nucleus 122 and Cf all
along the splitting process.Comment: 32 pages, 8 figure
Rotating Black Holes at Future Colliders. III. Determination of Black Hole Evolution
TeV scale gravity scenario predicts that the black hole production dominates
over all other interactions above the scale and that the Large Hadron Collider
will be a black hole factory. Such higher dimensional black holes mainly decay
into the standard model fields via the Hawking radiation whose spectrum can be
computed from the greybody factor. Here we complete the series of our work by
showing the greybody factors and the resultant spectra for the brane localized
spinor and vector field emissions for arbitrary frequencies. Combining these
results with the previous works, we determine the complete radiation spectra
and the subsequent time evolution of the black hole. We find that, for a
typical event, well more than half a black hole mass is emitted when the hole
is still highly rotating, confirming our previous claim that it is important to
take into account the angular momentum of black holes.Comment: typoes in eqs(82)-(84) corrected; version to appear in Phys. Rev. D;
references and a footnote added; same manuscript with high resolution
embedded figures available on
http://www.gakushuin.ac.jp/univ/sci/phys/ida/paper
Electromagnons in multiferroic YMn2O5 and TbMn2O5
Based on temperature dependent far infrared transmission spectra of YMn2O5
and TbMn2O5 single crystals, we report the observation of electric
dipole-active magnetic excitations, or electromagnons, in these multiferroics.
Electromagnons are found to be directly responsible for the step-like anomaly
of the static dielectric constant at the commensurate--incommensurate magnetic
transition and are the origin of the colossal magneto-dielectric effect
reported in these multiferroics.Comment: 4 pages, 4 figures, submitte
Parametric coupling between macroscopic quantum resonators
Time-dependent linear coupling between macroscopic quantum resonator modes
generates both a parametric amplification also known as a {}"squeezing
operation" and a beam splitter operation, analogous to quantum optical systems.
These operations, when applied properly, can robustly generate entanglement and
squeezing for the quantum resonator modes. Here, we present such coupling
schemes between a nanomechanical resonator and a superconducting electrical
resonator using applied microwave voltages as well as between two
superconducting lumped-element electrical resonators using a r.f.
SQUID-mediated tunable coupler. By calculating the logarithmic negativity of
the partially transposed density matrix, we quantitatively study the
entanglement generated at finite temperatures. We also show that
characterization of the nanomechanical resonator state after the quantum
operations can be achieved by detecting the electrical resonator only. Thus,
one of the electrical resonator modes can act as a probe to measure the
entanglement of the coupled systems and the degree of squeezing for the other
resonator mode.Comment: 15 pages, 4 figures, submitte
Hamiltonian Embedding of SU(2) Higgs Model in the Unitary Gauge
Following systematically the generalized Hamiltonian approach of Batalin,
Fradkin and Tyutin (BFT), we embed the second-class non-abelian SU(2) Higgs
model in the unitary gauge into a gauge invariant theory. The strongly
involutive Hamiltonian and constraints are obtained as an infinite power series
in the auxiliary fields. Furthermore, comparing these results with those
obtained from the gauged second class Lagrangian, we arrive at a simple
interpretation for the first class Hamiltonian, constraints and observables.Comment: 13 pages, Latex, no figure
Magnetic Anisotropy of Isolated Cobalt Nanoplatelets
Motivated in part by experiments performed by M.H. Pan et al. (nanoletters,
v.5, p 83, 2005), we have undertaken a theoretical study of the the magnetic
properties of two-monolayer thick Co nanoplatelets with an equilateral
triangular shape. The analysis is carried out using a microscopic Slater-Koster
tight-binding model with atomic exchange and spin-orbit interactions designed
to realistically capture the salient magnetic features of large nanoclusters
containing up to 350 atoms. Two different truncations of the FCC lattice are
studied, in which the nanoplatelet surface is aligned parallel to the FCC (111)
and (001)crystal planes respectively. We find that the higher coordination
number in the (111) truncated crystal is more likely to reproduce the
perpendicular easy direction found in experiment. Qualitatively, the most
important parameter governing the anisotropy of the model is found to be the
value of the intra-atomic exchange integral J. If we set the value of J near
the bulk value in order to reproduce the experimentally observed magnitude of
the magnetic moments, we find both quasi-easy-planes and perpendicular easy
directions. At larger values of J we find that the easy-axis of magnetization
is perpendicular to the surface, and the value of the magnetic anisotropy
energy per atom is larger. The possible role of hybridization with substrate
surface states in the experimental systems is discussed.Comment: 15 pages, 13 figure
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