1,644 research outputs found
Compulsary vaccination vs. Parental rights: a false conflict of rights
It is not unusual nowadays that some parents refuse their chindren to get vaccinated due to their religious beliefs or because they think it is a better way to protect their chindren health. This claim is allegedly supported by the freedom of religion and the right of parents to decide about some important aspects of their children’s life such as education or health care. This decisions may have effects on others and their right to health, thus turning the problem into a conflict of rights. This conflict, it is said, will justify the limitation of the parents right to decide about this issues. In this paper I will defend that there is no conflict at all and therefore no limitation of any right. I will defend a conception of rights that try to avoid the misunderstandings (about what rights are and how they work in legal reasoning) of a “conflicting conception of rights”. In other words, I will defend a conception of rights for which not leting the parents to put other’s health at risk is not a limitation of the right, but an action that lies beyond the boundaries of the right.Universidad de Málaga. Campus de Excelencia AndalucĂa Tech
Anharmonic effects in magnetoelastic chains
We describe a new mechanism leading to the formation of rational
magnetization plateau phases, which is mainly due to the anharmonic spin-phonon
coupling. This anharmonicity produces plateaux in the magnetization curve at
unexpected values of the magnetization without explicit magnetic frustration in
the Hamiltonian and without an explicit breaking of the translational symmetry.
These plateau phases are accompanied by magneto-elastic deformations which are
not present in the harmonic case.Comment: 5 pages, 3 figure
Quasiparticle operators with non-Abelian braiding statistics
We study the gauge invariant fermions in the fermion coset representation of
Wess-Zumino-Witten models which create, by construction, the physical
excitations (quasiparticles) of the theory. We show that they provide an
explicit holomorphic factorization of Wess-Zumino-Witten primaries
and satisfy non-Abelian braiding relations.Comment: 13 pages, no figures, final version to appear in Physics Letters
Local magnetic properties of periodic nonuniform spin-1/2 XX chains
Using the Jordan-Wigner fermionization, Green function approach and continued
fractions we examine rigorously the local magnetizations and the local static
susceptibilities of the spin-1/2 XX chain in a transverse field with regularly
varying exchange interactions. We discuss our findings from a viewpoint of the
strong-coupling approach.Comment: 15 pages, latex, 3 figure
Doping-dependent magnetization plateaux in p-merized Hubbard chains
We study zero-temperature Hubbard chains with periodically modulated hopping
at arbitrary filling n and magnetization m. We show that the magnetization
curves have plateaux at certain values of m which depend on the periodicity p
and the filling. At commensurate filling n a charge gap opens and then
magnetization plateaux correspond to fully gapped situations. However, plateaux
also arise in the magnetization curves at fixed n between the commensurate
values and then the plateau-value of of m depends continuously on n and can
thus also become irrational. In particular for the case of dimerized hopping
(p=2) and fixed doping we find that a plateau appears at m=1-n. In this case,
there is still a gapless mode on the plateau leading to thermodynamic behavior
which is different from a completely gapped situation.Comment: 9 pages REVTeX, 3 PostScript figures included using psfig.sty; this
is the final version to appear in Phys. Lett. A; substantial changes: Lanczos
part removed to gain space for further explanations (refer to original
version for details on the numerics
Duality in deformed coset fermionic models
We study the -parafermion model perturbed by its first thermal
operator. By formulating the theory in terms of a (perturbed) fermionic coset
model we show that the model is equivalent to interacting WZW fields modulo
free fields. In this scheme, the order and disorder operators of the
parafermion theory are constructed as gauge invariant composites. We find that
the theory presents a duality symmetry that interchanges the roles of the spin
and dual spin operators. For two particular values of the coupling constant we
find that the theory recovers conformal invariance and the gauge symmetry is
enlarged. We also find a novel self-dual point.Comment: 13 pages, LaTex. Minor corrections. One reference added. Version to
appear in Nuc. Phys.
Fermionic Coset Realization of Primaries in Critical Statistical Models
We obtain a fermionic coset realization of the primaries of minimal unitary
models and show how their four-point functions may be calculated by the use of
a reduction formula. We illustrate the construction for the Ising model, where
we obtain an explicit realization of the energy operator, Onsager fermions, as
well as of the order and disorder operators realizing the dual algebra, in
terms of constrained Dirac fermions. The four-point correlators of these
operators are shown to agree with those obtained by other methods.Comment: 26 pages, Latex fil
Influence of lattice distortions in classical spin systems
We investigate a simple model of a frustrated classical spin chain coupled to
adiabatic phonons under an external magnetic field. A thorough study of the
magnetization properties is carried out both numerically and analytically. We
show that already a moderate coupling with the lattice can stabilize a plateau
at 1/3 of the saturation and discuss the deformation of the underlying lattice
in this phase. We also study the transition to saturation where either a first
or second order transition can occur, depending on the couplings strength.Comment: Submitted to Phys. Rev.
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