16,244 research outputs found
Effects of a primordial magnetic field with log-normal distribution on the cosmic microwave background
We study the effect of primordial magnetic fields (PMFs) on the anisotropies
of the cosmic microwave background (CMB). We assume the spectrum of PMFs is
described by log-normal distribution which has a characteristic scale, rather
than power-law spectrum. This scale is expected to reflect the generation
mechanisms and our analysis is complementary to previous studies with power-law
spectrum. We calculate power spectra of energy density and Lorentz force of the
log-normal PMFs, and then calculate CMB temperature and polarization angular
power spectra from scalar, vector, and tensor modes of perturbations generated
from such PMFs. By comparing these spectra with WMAP7, QUaD, CBI, Boomerang,
and ACBAR data sets, we find that the current CMB data set places the strongest
constraint at Mpc with the upper limit
nG.Comment: 14 pages, 6 figure
Spectral sum rules for confining large-N theories
We consider asymptotically-free four-dimensional large- gauge theories
with massive fermionic and bosonic adjoint matter fields, compactified on
squashed three-spheres, and examine their regularized large- confined-phase
spectral sums. The analysis is done in the limit of vanishing 't Hooft
coupling, which is justified by taking the size of the compactification
manifold to be small compared to the inverse strong scale . Our
results motivate us to conjecture some universal spectral sum rules for these
large gauge theories.Comment: 25 pages, 2 figures. v2: fixed typos, added references, and some
minor improvements to discussio
Constraints on the neutrino mass and the primordial magnetic field from the matter density fluctuation parameter
We have made an analysis of limits on the neutrino mass based upon the
formation of large-scale structure in the presence of a primordial magnetic
field. We find that a new upper bound on the neutrino mass is possible based
upon fits to the cosmic microwave background and matter power spectrum when the
existing independent constraints on the matter density fluctuation parameter
and the primordial magnetic field are taken into account.Comment: 6 pages, 2 figures, final version to appear in Phys. Rev. D, to match
proof
Kaonic nuclei studied based on a new framework of Antisymmetric Molecular Dynamics
We have developed a new framework of Antisymmetrized Molecular Dynamics
(AMD), to adequately treat the I=0 \={K}N interaction, which is essential to
study kaonic nuclei. The improved points are 1) pK/n\={K} mixing and 2)
total spin and isospin projections. These improvements enable us to investigate
various kaonic nuclei (ppnK, pppK, pppnK, BeK and
BK) systematically. We have found that they are deeply bound and
extremely dense with a variety of shapes.Comment: 10 pages, 5 figure
Two-Nucleon Bound States in Quenched Lattice QCD
We address the issue of bound state in the two-nucleon system in lattice QCD.
Our study is made in the quenched approximation at the lattice spacing of a =
0.128 fm with a heavy quark mass corresponding to m_pi = 0.8 GeV. To
distinguish a bound state from an attractive scattering state, we investigate
the volume dependence of the energy difference between the ground state and the
free two-nucleon state by changing the spatial extent of the lattice from 3.1
fm to 12.3 fm. A finite energy difference left in the infinite spatial volume
limit leads us to the conclusion that the measured ground states for not only
spin triplet but also singlet channels are bounded. Furthermore the existence
of the bound state is confirmed by investigating the properties of the energy
for the first excited state obtained by 2x2 diagonalization method. The
scattering lengths for both channels are evaluated by applying the finite
volume formula derived by Luscher to the energy of the first excited states.Comment: 34 pages, 28 figure
Antikaon-nucleus dynamics: from quasibound states to kaon condensation
Coupled-channel Kbar-N dynamics near threshold and its repercussions in
few-body Kbar-nuclear systems are briefly reviewed, highlighting studies of a
K^-pp quasibound state. In heavier nuclei, the extension of mean-field
calculations to multi-Kbar nuclear and hypernuclear quasibound states is
discussed. It is concluded that strangeness in finite self-bound systems is
realized through hyperons, with no room for kaon condensation.Comment: Proceedings version of plenary talk at Quark Nuclear Physics (QNP09)
September 2009, Beijing; matches published versio
Casimir energy of confining large gauge theories
Four-dimensional asymptotically-free large gauge theories compactified on
have a weakly-coupled confining regime when is
small compared to the strong scale. We compute the vacuum energy of a variety
of confining large non-supersymmetric gauge theories in this calculable
regime, where the vacuum energy can be thought of as the Casimir energy.
The renormalized vacuum energy turns out to vanish in all of the
large gauge theories we have examined, confirming a striking prediction of
temperature-reflection symmetry.Comment: 4 pages, 1 figure. v2: added clarifications and typo corrections,
conclusions unchange
Optimal double stopping of a Brownian bridge
We study optimal double stopping problems driven by a Brownian bridge. The
objective is to maximize the expected spread between the payoffs achieved at
the two stopping times. We study several cases where the solutions can be
solved explicitly by strategies of threshold type
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