Hidden nonlinear supersymmetries in pure parabosonic systems

The existence of intimate relation between generalized statistics and supersymmetry is established by observation of hidden supersymmetric structure in pure parabosonic systems. This structure is characterized generally by a nonlinear superalgebra. The nonlinear supersymmetry of parabosonic systems may be realized, in turn, by modifying appropriately the usual supersymmetric quantum mechanics. The relation of nonlinear parabosonic supersymmetry to the Calogero-like models with exchange interaction and to the spin chain models with inverse-square interaction is pointed out.Comment: 20 pages, one reference corrected, to appear in Int. J. Mod. Phys.

Proposed New Antiproton Experiments at Fermilab

Fermilab operates the world's most intense source of antiprotons. Recently various experiments have been proposed that can use those antiprotons either parasitically during Tevatron Collider running or after the Tevatron Collider finishes in about 2010. We discuss the physics goals and prospects of the proposed experiments.Comment: 6 pages, 2 figures, to appear in Proceedings of IXth International Conference on Low Energy Antiproton Physics (LEAP'08), Vienna, Austria, September 16 to 19, 200

Nambu-Goldstone Modes in Gravitational Theories with Spontaneous Lorentz Breaking

Spontaneous breaking of Lorentz symmetry has been suggested as a possible mechanism that might occur in the context of a fundamental Planck-scale theory, such as string theory or a quantum theory of gravity. However, if Lorentz symmetry is spontaneously broken, two sets of questions immediately arise: what is the fate of the Nambu-Goldstone modes, and can a Higgs mechanism occur? A brief summary of some recent work looking at these questions is presented here.Comment: 6 pages. Presented at the meeting "From Quantum to Cosmos," Washington, D.C., May 2006; published in Int. J. Mod. Phys. D16:2357-2363, 200

Technically natural dark energy from Lorentz breaking

We construct a model of dark energy with a technically natural small contribution to cosmic acceleration, i.e. this contribution does not receive corrections from other scales in the theory. The proposed acceleration mechanism appears generically in the low-energy limit of gravity theories with violation of Lorentz invariance that contain a derivatively coupled scalar field Theta. The latter may be the Goldstone field of a broken global symmetry. The model, that we call Theta-CDM, is a valid effective field theory up to a high cutoff just a few orders of magnitude below the Planck scale. Furthermore, it can be ultraviolet-completed in the context of Horava gravity. We discuss the observational predictions of the model. Even in the absence of a cosmological constant term, the expansion history of the Universe is essentially indistinguishable from that of Lambda-CDM. The difference between the two theories appears at the level of cosmological perturbations. We find that in Theta-CDM the matter power spectrum is enhanced at subhorizon scales compared to Lambda-CDM. This property can be used to discriminate the model from Lambda-CDM with current cosmological data.Comment: A few equations in the Appendix correcte

Quantum Criticality of an Ising-like Spin-1/2 Antiferromagnetic Chain in Transverse Magnetic Field

We report on magnetization, sound velocity, and magnetocaloric-effect measurements of the Ising-like spin-1/2 antiferromagnetic chain system BaCo$_2$V$_2$O$_8$ as a function of temperature down to 1.3 K and applied transverse magnetic field up to 60 T. While across the N\'{e}el temperature of $T_N\sim5$ K anomalies in magnetization and sound velocity confirm the antiferromagnetic ordering transition, at the lowest temperature the field-dependent measurements reveal a sharp softening of sound velocity $v(B)$ and a clear minimum of temperature $T(B)$ at $B^{c,3D}_\perp=21.4$ T, indicating the suppression of the antiferromagnetic order. At higher fields, the $T(B)$ curve shows a broad minimum at $B^c_\perp = 40$ T, accompanied by a broad minimum in the sound velocity and a saturation-like magnetization. These features signal a quantum phase transition which is further characterized by the divergent behavior of the Gr\"{u}neisen parameter $\Gamma_B \propto (B-B^{c}_\perp)^{-1}$. By contrast, around the critical field, the Gr\"{u}neisen parameter converges as temperature decreases, pointing to a quantum critical point of the one-dimensional transverse-field Ising model.Comment: Phys. Rev. Lett., to appea

First-order thermal correction to the quadratic response tensor and rate for second harmonic plasma emission

Three-wave interactions in plasmas are described, in the framework of kinetic theory, by the quadratic response tensor (QRT). The cold-plasma QRT is a common approximation for interactions between three fast waves. Here, the first-order thermal correction (FOTC) to the cold-plasma QRT is derived for interactions between three fast waves in a warm unmagnetized collisionless plasma, whose particles have an arbitrary isotropic distribution function. The FOTC to the cold-plasma QRT is shown to depend on the second moment of the distribution function, the phase speeds of the waves, and the interaction geometry. Previous calculations of the rate for second harmonic plasma emission (via Langmuir-wave coalescence) assume the cold-plasma QRT. The FOTC to the cold-plasma QRT is used here to calculate the FOTC to the second harmonic emission rate, and its importance is assessed in various physical situations. The FOTC significantly increases the rate when the ratio of the Langmuir phase speed to the electron thermal speed is less than about 3.Comment: 11 pages, 2 figures, submitted to Physics of Plasma

Grupos de turismo e lazer como um mecanismo organizacional e econômico para controlar a formação e o desenvolvimento da capacidade inovadora do Distrito Federal do Norte do Cáucaso

This article highlights the importance of the strategic approach for managing the tourism and recreation sector at the regional level. This article analyzes a relevant topic not studied before, consisting of considering tourism and the recreational group as an organizational and economic mechanism to control the formation and development of innovative capacities in the Federal District of the North Caucasus. The original methodological approach has been designed for the evaluation of the formation and development of the tourist cluster. It can also be used to evaluate clustering in the sphere of tourism, the efficiency of the tourist cluster, the synergy effect, which is based on an integral method of measurement definition and heterogeneity indices. All these characteristics distinguish this method from the existing ones and allow to evaluate its implementation for the cluster policy in the tourist sphere. The management and economic proposals for the development of tourist groups are represented here: Organization of the group development center, design of the management structure and identification of the stages of development. The model of the North Caucasus Federal District for the tourism group has been designed and covers its specialization and functional directions of the companies defined by identifying a specific variety of the tourism industry. The authors affirm that the cluster policy is the key element to implement the objectives related to the development of the tourism industry in the regions with innovative capacity and economic development of the whole country.Este artículo destaca la importancia del enfoque estratégico para la gestión del sector del turismo y la recreación a nivel regional. En este artículo se analiza un tema relevante no estudiado antes, consistente en plantear el turismo y el grupo recreativo como mecanismo organizativo y económico de control de la formación y desarrollo de capacidades innovadoras en el Distrito Federal del Norte del Cáucaso. El enfoque metodológico original ha sido diseñado para la evaluación de la formación y el desarrollo del cluster turístico. También se puede utilizar para evaluar la agrupación en la esfera del turismo, la eficiencia del clúster turístico, el efecto de sinergia, que se basa en un método integral de definición de medida e índices de heterogeneidad. Todas estas características distinguen este método de los existentes y permiten evaluar su implementación para la política de cluster en la esfera turística. Las propuestas de gestión y económicas para el desarrollo de agrupaciones de turistas están representadas aquí: Organización del centro de desarrollo de agrupaciones, diseño de la estructura de gestión e identificación de las etapas de desarrollo. El modelo del Distrito Federal del Cáucaso Norte para el grupo de turismo ha sido diseñado y abarca su especialización y direcciones funcionales de las empresas definidas mediante la identificación de una variedad específica de la industria turística. Los autores afirman que la política de cluster es el elemento clave para implementar los objetivos relacionados con el desarrollo de la industria del turismo en las regiones con capacidad innovadora y desarrollo económico de todo el país.Este artigo destaca a importância da abordagem estratégica para a gestão do setor de turismo e recreação em nível regional. Este artigo analisa um tópico relevante não estudado anteriormente, que consiste em considerar o turismo e o grupo de lazer como um mecanismo organizacional e econômico para controlar a formação e o desenvolvimento de capacidades inovadoras no Distrito Federal do Norte do Cáucaso. A abordagem metodológica original foi concebida para a avaliação da formação e desenvolvimento do cluster turístico. Ele também pode ser usado para avaliar o agrupamento na esfera do turismo, a eficiência do cluster turístico, o efeito de sinergia, que é baseado em um método integral de definição de medida e índices de heterogeneidade. Todas essas características distinguem este método das existentes e permitem avaliar sua implementação para a política de cluster na esfera turística. As propostas econômicas e de gestão para o desenvolvimento de grupos de turistas são representadas aqui: Organização do centro de desenvolvimento do grupo, desenho da estrutura de gestão e identificação das etapas de desenvolvimento. O modelo do Distrito Federal do Norte do Cáucaso para o grupo de turismo foi projetado e abrange sua especialização e direções funcionais das empresas definidas pela identificação de uma variedade específica da indústria do turismo. Os autores afirmam que a política de cluster é o elemento chave para implementar os objetivos relacionados ao desenvolvimento da indústria do turismo nas regiões com capacidade inovadora e desenvolvimento econômico de todo o país