1,477 research outputs found
DMRG Study of Critical Behavior of the Spin-1/2 Alternating Heisenberg Chain
We investigate the critical behavior of the S=1/2 alternating Heisenberg
chain using the density matrix renormalization group (DMRG). The ground-state
energy per spin and singlet-triplet energy gap are determined for a range of
alternations. Our results for the approach of the ground-state energy to the
uniform chain limit are well described by a power law with exponent p=1.45. The
singlet-triplet gap is also well described by a power law, with a critical
exponent of p=0.73, half of the ground-state energy exponent. The
renormalization group predictions of power laws with logarithmic corrections
can also accurately describe our data provided that a surprisingly large scale
parameter is present in the logarithm.Comment: 6 pages, 4 eps-figure
Organizational health climate matters: Cross-level findings from the CDC National Healthy Worksite Program.
The signal of in nucleon-antinucleon scattering
We study the production of at a nucleon-antinucleon scattering
experiment. Considering the PANDA experiment to be an ideal platform to explore
the production of the charmonium and charmonim-like states, we suggest the
forthcoming PANDA experiment to pay attention to the production of
.Comment: 6 pages, 15 figures. Published version in EPJ
Lattice calculation of hybrid mesons with improved Kogut-Susskind fermions
We report on a lattice determination of the mass of the exotic
hybrid meson using an improved Kogut-Susskind action. Results from both
quenched and dynamical quark simulations are presented. We also compare with
earlier results using Wilson quarks at heavier quark masses. The results on
lattices with three flavors of dynamical quarks show effects of sea quarks on
the hybrid propagators which probably result from coupling to two meson states.
We extrapolate the quenched results to the physical light quark mass to allow
comparison with experimental candidates for the hybrid meson. The
lattice result remains somewhat heavier than the experimental result, although
it may be consistent with the .Comment: 24 pages, 12 figures. Replaced to match published versio
Understanding Schools and Schooling. (Book Review)
A review of a book written by Clive Chitty (2002 with a useful focus on issues of equity and social justice, including prejudice, discrimination and bullying in secondary schools. Education policy makers need to explore the extent to which it is important to produce interested, motivated and socially balanced young adults. It is well researched and documented
Chiral radiative corrections and D_s(2317)/D(2308) mass puzzle
We show that one loop chiral corrections for heavy-light mesons in potential
model can explain the small mass of D_s(2317) as well as the small mass gap
between D_s(2317) and D(2308).Comment: To appear in EPJC. A figure and references addede
Probing Yukawian gravitational potential by numerical simulations. I. Changing N-body codes
In the weak field limit general relativity reduces, as is well known, to the
Newtonian gravitation. Alternative theories of gravity, however, do not
necessarily reduce to Newtonian gravitation; some of them, for example, reduce
to Yukawa-like potentials instead of the Newtonian potential. Since the
Newtonian gravitation is largely used to model with success the structures of
the universe, such as for example galaxies and clusters of galaxies, a way to
probe and constrain alternative theories, in the weak field limit, is to apply
them to model the structures of the universe. In the present study, we consider
how to probe Yukawa-like potentials using N-body numerical simulations.Comment: 17 pages, 11 figures. To appear in General Relativity and Gravitatio
Atomic Model of Susy Hubbard Operators
We apply the recently proposed susy Hubbard operators to an atomic model. In
the limiting case of free spins, we derive exact results for the entropy which
are compared with a mean field + gaussian corrections description. We show how
these results can be extended to the case of charge fluctuations and calculate
exact results for the partition function, free energy and heat capacity of an
atomic model for some simple examples. Wavefunctions of possible states are
listed. We compare the accuracy of large N expansions of the susy spin
operators with those obtained using `Schwinger bosons' and `Abrikosov
pseudo-fermions'. For the atomic model, we compare results of slave boson,
slave fermion, and susy Hubbard operator approximations in the physically
interesting but uncontrolled limiting case of N->2. For a mixed representation
of spins we estimate the accuracy of large N expansions of the atomic model. In
the single box limit, we find that the lowest energy saddle-point solution
reduces to simply either slave bosons or slave fermions, while for higher boxes
this is not the case. The highest energy saddle-point solution has the
interesting feature that it admits a small region of a mixed representation,
which bears a superficial resemblance to that seen experimentally close to an
antiferromagnetic quantum critical point.Comment: 17 pages + 7 pages Appendices, 14 figures. Substantial revision
Coulomb Gauge QCD, Confinement, and the Constituent Representation
Quark confinement and the genesis of the constituent quark model are examined
in nonperturbative QCD in Coulomb gauge. We employ a self-consistent method to
construct a quasiparticle basis and to determine the quasiparticle interaction.
The results agree remarkably well with lattice computations. They also
illustrate the mechanism by which confinement and constituent quarks emerge,
provide support for the Gribov-Zwanziger confinement scenario, clarify several
perplexing issues in the constituent quark model, and permit the construction
of an improved model of low energy QCD.Comment: 43 pages, 14 figures, revtex, uses psfig.st
Plasma Turbulence in the Local Bubble
Turbulence in the Local Bubble could play an important role in the
thermodynamics of the gas that is there. The best astronomical technique for
measuring turbulence in astrophysical plasmas is radio scintillation.
Measurements of the level of scattering to the nearby pulsar B0950+08 by
Philips and Clegg in 1992 showed a markedly lower value for the line-of-sight
averaged turbulent intensity parameter is smaller than normal for two of them, but is completely nominal for
the third. This inconclusive status of affairs could be improved by
measurements and analysis of ``arcs'' in ``secondary spectra'' of pulsars.Comment: Submitted to Space Science Reviews as contribution to Proceedings of
ISSI (International Space Science Institute) workshop "From the Heliosphere
to the Local Bubble". Refereed version accepted for publicatio
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