13,842 research outputs found
Topological mass generation to antisymmetric tensor matter field
We propose a mechanism to give mass to tensor matter field which preserve the
U(1) symmetry. We introduce a complex vector field that couples with the tensor
in a topological term. We also analyze the influence of the kinetic terms of
the complex vector in our mechanism.Comment: 5 pages, to appear in Europhysics Letter
Coherent and semiclassical states in magnetic field in the presence of the Aharonov-Bohm solenoid
A new approach to constructing coherent states (CS) and semiclassical states
(SS) in magnetic-solenoid field is proposed. The main idea is based on the fact
that the AB solenoid breaks the translational symmetry in the xy-plane, this
has a topological effect such that there appear two types of trajectories which
embrace and do not embrace the solenoid. Due to this fact, one has to construct
two different kinds of CS/SS, which correspond to such trajectories in the
semiclassical limit. Following this idea, we construct CS in two steps, first
the instantaneous CS (ICS) and the time dependent CS/SS as an evolution of the
ICS. The construction is realized for nonrelativistic and relativistic spinning
particles both in (2+1)- and (3+1)- dimensions and gives a non-trivial example
of SS/CS for systems with a nonquadratic Hamiltonian. It is stressed that CS
depending on their parameters (quantum numbers) describe both pure quantum and
semiclassical states. An analysis is represented that classifies parameters of
the CS in such respect. Such a classification is used for the semiclassical
decompositions of various physical quantities.Comment: 35 pages, 2 figures. Some typos in (77), (101), and (135) corrected
with respect to the published version. Results unchange
Antisymmetric tensor propagator with spontaneous Lorentz violation
In this work, we study the spontaneous Lorentz symmetry breaking due to an
antisymmetric 2-tensor field in Minkowski spacetime. For a smooth quadratic
potential, the spectrum of the theory exhibits massless and massive
excitations. We show that the equations of motion for the free field obey some
constraints which lead to the massive mode be non-propagating at leading order.
Besides, there exists a massless mode in the theory which can be identified
with the usual Kalb-Ramond field, carrying only one on-shell degree of freedom.
The same conclusion holds when one analyses the pole structure of its Feynman
propagator. A new complete set of spin-type operators is found, which was the
requirement to evaluate the propagator of the Kalb-Ramond field modified by the
presence of a nonzero vacuum expectation value responsible for the Lorentz
violation.Comment: 13 pages. Some modifications to match published version in
EuroPhysics Letter
Avaliação de clones de mandioca de mesa.
Embora o gênero Manihot seja formado por 80-90 espécies, toda a mandioca cultivada pertence a uma única espécie, Manihot esculenta Crantz. Os clones de mandioca são divididos em dois grupos, com base no teor de compostos cianogênicos. Aqueles com teor abaixo de 100 ppm são considerados como mandioca de mesa, aipim ou macaxeira, e aqueles com acima de 100 ppm são mandioca brava, utilizada para a produção de farinha
Spin Dynamics of in the Field-Induced Ordered Phase
- (known as DTN) is a spin-1 material with a strong
single-ion anisotropy that is regarded as a new candidate for Bose-Einstein
condensation (BEC) of spin degrees of freedom. We present a systematic study of
the low-energy excitation spectrum of DTN in the field-induced magnetically
ordered phase by means of high-field electron spin resonance measurements at
temperatures down to 0.45 K. We argue that two gapped modes observed in the
experiment can be consistently interpreted within a four-sublattice
antiferromagnet model with a finite interaction between two tetragonal
subsystems and unbroken axial symmetry. The latter is crucial for the
interpretation of the field-induced ordering in DTN in terms of BEC.Comment: 4 pages, 3 figure
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