13,058 research outputs found
Fermion-boson duality in integrable quantum field theory
We introduce and study one parameter family of integrable quantum field
theories. This family has a Lagrangian description in terms of massive Thirring
fermions and charged bosons of complex
sinh-Gordon model coupled with affine Toda theory. Perturbative
calculations, analysis of the factorized scattering theory and the Bethe ansatz
technique are applied to show that under duality transformation, which relates
weak and strong coupling regimes of the theory the fermions
transform to bosons and and vive versa.
The scattering amplitudes of neutral particles in this theory coincide exactly
with S-matrix of particles in pure
Toda theory, i.e. the contribution of charged bosons and fermions to these
amplitudes exactly cancel each other. We describe and discuss the symmetry
responsible for this compensation property.Comment: 12 pages, LaTex file with amste
The end of secularization in Europe? A socio-demographic perspective
Much of the current debate over secularization in Europe focuses only on the direction of religious change, and pays exclusive attention to social causes. Scholars have been less attentive to shifts in the rate of religious decline, and to the role of demography – notably fertility and immigration. This article addresses both phenomena. It uses data from the European Values Surveys and European Social Survey for the period 1981-2008 to establish basic trends in religious attendance and belief across the ten countries that have been consistently surveyed. These show that religious decline is mainly occurring in Catholic European countries and has effectively ceased among post-1945 birth cohorts in six northwestern European societies where secularization began early. It also provides a cohort component projection of religious affiliation for two European countries using fertility, migration, switching and age and sex-structure parameters derived from census and immigration data. These suggest that western Europe may be more religious at the end of our century than at its beginning
Symplectic N and time reversal in frustrated magnetism
Identifying the time reversal symmetry of spins as a symplectic symmetry, we
develop a large N approximation for quantum magnetism that embraces both
antiferromagnetism and ferromagnetism. In SU(N), N>2, not all spins invert
under time reversal, so we have introduced a new large N treatment which builds
interactions exclusively out of the symplectic subgroup [SP(N)] of time
reversing spins, a more stringent condition than the symplectic symmetry of
previous SP(N) large N treatments. As a result, we obtain a mean field theory
that incorporates the energy cost of frustrated bonds. When applied to the
frustrated square lattice, the ferromagnetic bonds restore the frustration
dependence of the critical spin in the Neel phase, and recover the correct
frustration dependence of the finite temperature Ising transition.Comment: added reference
A Characterisation of the Weylian Structure of Space-Time by Means of Low Velocity Tests
The compatibility axiom in Ehlers, Pirani and Schild's (EPS) constructive
axiomatics of the space-time geometry that uses light rays and freely falling
particles with high velocity, is replaced by several constructions with low
velocity particles only. For that purpose we describe in a space-time with a
conformal structure and an arbitrary path structure the radial acceleration, a
Coriolis acceleration and the zig-zag construction. Each of these quantities
give effects whose requirement to vanish can be taken as alternative version of
the compatibility axiom of EPS. The procedural advantage lies in the fact, that
one can make null-experiments and that one only needs low velocity particles to
test the compatibility axiom. We show in addition that Perlick's standard clock
can exist in a Weyl space only.Comment: to appear in Gen.Rel.Gra
Theta Dependence In The Large N Limit Of Four-Dimensional Gauge Theories
The theta dependent of pure gauge theories in four dimensions can be studied
using a duality of large N gauge theories with string theory on a certain
spacetime. Via this duality, one can argue that for every theta, there are
infinitely many vacua that are stable in the large N limit. The true vacuum,
found by minimizing the energy in this family, is a smooth function of theta
except at theta equal to pi, where it jumps. This jump is associated with
spontaneous breaking of CP symmetry. Domain walls separating adjacent vacua are
described in terms of wrapped sixbranes.Comment: 8 p
Entanglement Measure for Composite Systems
A general description of entanglement is suggested as an action realized by
an arbitrary operator over given disentangled states. The related entanglement
measure is defined. Because of its generality, this definition can be employed
for any physical systems, pure or mixed, equilibrium or nonequilibrium, and
characterized by any type of operators, whether these are statistical
operators, field operators, spin operators, or anything else. Entanglement of
any number of parts from their total ensemble forming a multiparticle composite
system can be determined. Interplay between entanglement and ordering,
occurring under phase transitions, is analysed by invoking the concept of
operator order indices.Comment: 6 pages, Revte
A Lattice Test of 1/N_c Baryon Mass Relations
1/N_c baryon mass relations are compared with lattice simulations of baryon
masses using different values of the light-quark masses, and hence different
values of SU(3) flavor-symmetry breaking. The lattice data clearly display both
the 1/N_c and SU(3) flavor-symmetry breaking hierarchies. The validity of 1/N_c
baryon mass relations derived without assuming approximate SU(3)
flavor-symmetry also can be tested by lattice data at very large values of the
strange quark mass. The 1/N_c expansion constrains the form of discretization
effects; these are suppressed by powers of 1/N_c by taking suitable
combinations of masses. This 1/N_c scaling is explicitly demonstrated in the
present work.Comment: 13 pages, 20 figures; v2 version to be published in PR
Spontaneously Broken Spacetime Symmetries and Goldstone's Theorem
Goldstone's theorem states that there is a massless mode for each broken
symmetry generator. It has been known for a long time that the naive
generalization of this counting fails to give the correct number of massless
modes for spontaneously broken spacetime symmetries. We explain how to get the
right count of massless modes in the general case, and discuss examples
involving spontaneously broken Poincare and conformal invariance.Comment: 4 pages; 1 figure; v2: minor corrections. version to appear on PR
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