1,193 research outputs found
Implementing PCAC in Nonperturbative Models of Pion Production
Traditional few-body descriptions of pion production use integral equations
to sum the strong interactions nonperturbatively. Although much physics is
thereby included, there has not been a practical way of incorporating the
constraints of chiral symmetry into such approaches. Thus the traditional
few-body descriptions fail to reflect the underlying theory of strong
interactions, QCD, which is largely chirally symmetric. In addition, the lack
of chiral symmetry in the few-body approaches means that their predictions of
pion production are in principle not consistent with the partial conservation
of axial current (PCAC), a fact that has especially large consequences at low
energies. We discuss how the recent introduction of the ``gauging of equations
method'' can be used to include PCAC into traditional few-body descriptions and
thereby solve this long standing problemComment: Contribution to Proceedings, 1st Asia-Pacific Conference on Few-Body
Problems in Physics, Noda/Kashiwa, Japan, 23-28 August 1999, to be published
by Springer-Verlag as "Few-Body Systems Supplement". 7 pages, revtex, epsf, 3
Postscript figure
Imprints of the nuclear symmetry energy on gravitational waves from the axial w-modes of neutron stars
The eigen-frequencies of the axial w-modes of oscillating neutron stars are
studied using the continued fraction method with an Equation of State (EOS)
partially constrained by the recent terrestrial nuclear laboratory data. It is
shown that the density dependence of the nuclear symmetry energy
affects significantly both the frequencies and the damping
times of these modes. Besides confirming the previously found universal
behavior of the mass-scaled eigen-frequencies as functions of the compactness
of neutron stars, we explored several alternative universal scaling functions.
Moreover, the -mode is found to exist only for neutron stars having a
compactness of independent of the EOS used.Comment: Version appeared in Phys. Rev. C80, 025801 (2009
On the S-wave piD-scattering length in the relativistic field theory model of the deuteron
The S-wave scattering length of the strong pion-deuteron (pi D) scattering is
calculated in the relativistic field theory model of the deuteron suggested in
[1,2].The theoretical result agrees well with the experimental data. The
important role of the Delta-resonance contribution to the elastic pi
D-scattering is confirmed.Comment: 7 pages, no figures, accepted for publication in Z. Phys.
The Nucleon Electric Dipole Form Factor From Dimension-Six Time-Reversal Violation
We calculate the electric dipole form factor of the nucleon that arises as a
low-energy manifestation of time-reversal violation in quark-gluon interactions
of effective dimension 6: the quark electric and chromoelectric dipole moments,
and the gluon chromoelectric dipole moment. We use the framework of two-flavor
chiral perturbation theory to one loop
Coupling Unification, GUT-Scale Baryogenesis and Neutron-Antineutron Oscillation in SO(10)
We show that unification of the three gauge couplings can be realized
consistently in a class of non-supersymmetric SO(10) models with a one-step
breaking to the Standard Model if a color-sextet scalar field survives down to
the TeV scale. Such scalars, which should be accessible to the LHC for direct
detection, arise naturally in SO(10) as remnants of the seesaw mechanism for
neutrino masses. The diquark couplings of these scalars lead to \Delta B = 2
baryon number violating processes such as neutron-antineutron oscillation. We
estimate the free neutron-antineutron transition time to be \tau_{n-\bar{n}}
\approx (10^9-10^{12}) sec., which is in the interesting range for next
generation n-\bar{n} oscillation experiments. These models also realize
naturally the recently proposed (B-L)-violating GUT scale baryogenesis which
survives to low temperatures unaffected by the electroweak sphaleron
interactions.Comment: 15 pages, 4 eps figures, references added, to appear in Phys. Lett.
Measuring transverse velocities in gravitationally lensed extragalactic systems using an annual parallax effect
A parallax method to determine transverse velocity in a gravitationally
lensed system is described. Using the annual motion of the Earth around the Sun
allows us to probe the local structure of the magnification map that, under
certain assumptions, can be used to infer the effective transverse velocity.
The method is applied to OGLE data for QSO2237+0305 and the velocity value is
estimated to be about (15 +/- 10) km/s if attributed to the lensing galaxy or
about (420 +/- 300) km/s if attributed to the quasar. We find this estimate
unreasonably small and conclude that we have not measured a parallax effect. We
give a short list of properties that a system should possess to allow a
successful implementation of this method.Comment: v2: journal reference update
Radiation effects in glasses used for immobilization of high-level waste and plutonium disposition
This paper is a comprehensive review of the state-of-knowledge in the field of radiation effects in glasses that are to be used for the immobilization of high-level nuclear waste and plutonium disposition. The current status and issues in the area of radiation damage processes, defect generation, microstructure development, theoretical methods and experimental methods ase reviewed. Questions of fundamental and technological interest that offer opportunities for research are identified
Radial-orbit instability in modified Newtonian dynamics
The stability of radially anisotropic spherical stellar systems in modified
Newtonian dynamics (MOND) is explored by means of numerical simulations
performed with the N-body code N-MODY. We find that Osipkov-Merritt MOND models
require for stability larger minimum anisotropy radius than equivalent
Newtonian systems (ENSs) with dark matter, and also than purely baryonic
Newtonian models with the same density profile. The maximum value for stability
of the Fridman-Polyachenko-Shukhman parameter in MOND models is lower than in
ENSs, but higher than in Newtonian models with no dark matter. We conclude that
MOND systems are substantially more prone to radial-orbit instability than ENSs
with dark matter, while they are able to support a larger amount of kinetic
energy stored in radial orbits than purely baryonic Newtonian systems. An
explanation of these results is attempted, and their relevance to the MOND
interpretation of the observed kinematics of globular clusters, dwarf
spheroidal and elliptical galaxies is briefly discussed.Comment: 9 pages, 4 figures, accepted for publication in MNRA
Equation of state of isospin-asymmetric nuclear matter in relativistic mean-field models with chiral limits
Using in-medium hadron properties according to the Brown-Rho scaling due to
the chiral symmetry restoration at high densities and considering naturalness
of the coupling constants, we have newly constructed several relativistic
mean-field Lagrangians with chiral limits. The model parameters are adjusted
such that the symmetric part of the resulting equation of state at supra-normal
densities is consistent with that required by the collective flow data from
high energy heavy-ion reactions, while the resulting density dependence of the
symmetry energy at sub-saturation densities agrees with that extracted from the
recent isospin diffusion data from intermediate energy heavy-ion reactions. The
resulting equations of state have the special feature of being soft at
intermediate densities but stiff at high densities naturally. With these
constrained equations of state, it is found that the radius of a 1.4
canonical neutron star is in the range of 11.9 kmR13.1 km, and the
maximum neutron star mass is around 2.0 close to the recent
observations.Comment: 14 pages, 3 figure
Large and Unified Description of Quark and Lepton Mixing Matrices
We present a revised version of the so-called "yukawaon model", which was
proposed for the purpose of a unified description of the lepton mixing matrix
and the quark mixing matrix . It is assumed from a
phenomenological point of view that the neutrino Dirac mass matrix is
given with a somewhat different structure from the charged lepton mass matrix
, although was assumed in the previous model. As a result, the
revised model predicts a reasonable value with
keeping successful results for other parameters in as well as
and quark and lepton mass ratios.Comment: 13 pages, 3 figures, version accepted by EPJ
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