3,347 research outputs found
Quantum spin glass in anisotropic dipolar systems
The spin-glass phase in the \LHx compound is considered. At zero transverse
field this system is well described by the classical Ising model. At finite
transverse field deviations from the transverse field quantum Ising model are
significant, and one must take properly into account the hyperfine
interactions, the off-diagonal terms in the dipolar interactions, and details
of the full J=8 spin Hamiltonian to obtain the correct physical picture. In
particular, the system is not a spin glass at finite transverse fields and does
not show quantum criticality.Comment: 6 pages, 2 figures, to appear in J. Phys. Condens. Matter
(proceedings of the HFM2006 conference
Supersymmetric Higgs Triplets and Bilinear R-Parity Nonconservation
The supersymmetric standard model of particle interactions is extended to
include two Higgs triplet superfields at the TeV scale, carrying two units of
lepton number. Realistic tree-level Majorana neutrino masses are obtained in
the presence of soft, i.e. bilinear, R-parity nonconservation.Comment: 5 pages, no figur
Elastic scattering of solar neutrinos with electromagnetic moments
We consider the azimuthal asymmetry of the recoil electrons in elastic scattering of solar neutrinos, which can arise if neutrinos have
electromagnetic moments and there is a large solar magnetic field. We show that
using this effect it is not possible to distinguish between magnetic and
electric dipole moment in the 1-Dirac and 2-Majorana neutrino cases and that
averaging over neutrino energy is important and suppresses the azimuthal
asymmetry in the 2-Majorana case.Comment: 4 pages, Talk given by T. Schwetz at EuroConference on Frontiers in
Particle Astrophysics and Cosmology, San Feliu de Guixols, Spain, 30 Sept.-5
Oct. 200
Low energy scattering with a nontrivial pion
An earlier calculation in a generalized linear sigma model showed that the
well-known current algebra formula for low energy pion pion scattering held
even though the massless Nambu Goldstone pion contained a small admixture of a
two-quark two-antiquark field. Here we turn on the pion mass and note that the
current algebra formula no longer holds exactly. We discuss this small
deviation and also study the effects of an SU(3) symmetric quark mass type term
on the masses and mixings of the eight SU(3) multiplets in the model. We
calculate the s wave scattering lengths, including the beyond current algebra
theorem corrections due to the scalar mesons, and observe that the model can
fit the data well. In the process, we uncover the way in which linear sigma
models give controlled corrections (due to the presence of scalar mesons) to
the current algebra scattering formula. Such a feature is commonly thought to
exist only in the non-linear sigma model approach.Comment: 15 pages, 8 figure
Multiflavor Massive Schwinger Model With Non-Abelian Bosonization
We revisit the treatment of the multiflavor massive Schwinger model by non-Abelian Bosonization. We compare three different approximations to the low-lying spectrum: i) reading it off from the bosonized Lagrangian (neglecting interactions), ii) semi-classical quantization of the static soliton, iii) approximate semi-classical quantization of the ``breather'' solitons. A number of new points are made in this process. We also suggest a different ``effective low-energy Lagrangian'' for the theory which permits easy calculation of the low-energy scattering amplitudes. It correlates an exact mass formula of the system with the requirement of the Mermin-Wagner theorem
Note on Triangle Anomalies and Assignment of Singlet in 331-like Model
It is pointed out that in the like model which uses both fundamental
and complex conjugate representations for an assignment of the representations
to the left-handed quarks and the scalar representation to their corresponding
right-handed counterparts, the nature of the scalar should be taken into
account in order to make the fermion triangle anomalies in the theory
anomaly-free, i.e. renormalizable in a sense with no anomalies, even after the
spontaneous symmetry breaking.Comment: 8 page no figures, acknowledgments adde
Is Weak Pseudo-Hermiticity Weaker than Pseudo-Hermiticity?
For a weakly pseudo-Hermitian linear operator, we give a spectral condition
that ensures its pseudo-Hermiticity. This condition is always satisfied
whenever the operator acts in a finite-dimensional Hilbert space. Hence weak
pseudo-Hermiticity and pseudo-Hermiticity are equivalent in finite-dimensions.
This equivalence extends to a much larger class of operators. Quantum systems
whose Hamiltonian is selected from among these operators correspond to
pseudo-Hermitian quantum systems possessing certain symmetries.Comment: published version, 10 page
Bi-maximal mixing at GUT, the low energy data and the leptogenesis
In the framework of the minimum supersymmetric model with right-handed
neutrinos, we consider the Bi-maximal mixing which is realized at the GUT scale
and discuss a question that this model can reproduce the low energy phenomena
and the leptogenesis.Comment: Talk given by E. Takasugi at NuFact04, Osaka, Japan, July 26 - August
1,2004 - 3 pages, 4 figure
- …