Relativistic deuteron structure function at large Q^2

The deuteron deep inelastic unpolarized structure function F_2^D is calculated using the Wilson operator product expansion method. The long distance behaviour, related to the deuteron bound state properties, is evaluated using the Bethe-Salpeter equation with one particle on mass shell. The calculation of the ratio F_2^D/F_2^N is compared with other convolution models showing important deviations in the region of large x. The implications in the evaluation of the neutron structure function from combined data on deuterons and protons are discussed.Comment: 7 pages, 1 ps figure, RevTeX source, 1 tar.gz file. Submited to Physical Letter

Thermodynamics of quantum crystalline membranes

We investigate the thermodynamic properties and the lattice stability of two-dimensional crystalline membranes, such as graphene and related compounds, in the low temperature quantum regime $T\rightarrow0$. A key role is played by the anharmonic coupling between in-plane and out-of plane lattice modes that, in the quantum limit, has very different consequences than in the classical regime. The role of retardation, namely of the frequency dependence, in the effective anharmonic interactions turns out to be crucial in the quantum regime. We identify a crossover temperature, $T^{*}$, between classical and quantum regimes, which is $\sim 70 - 90$ K for graphene. Below $T^{*}$, the heat capacity and thermal expansion coefficient decrease as power laws with decreasing temperature, tending to zero for $T\rightarrow0$ as required by the third law of thermodynamics.Comment: 13 pages, 1 figur

Reply to 'Comment on "Thermodynamics of quantum crystalline membranes"'

In this note, we reply to the comment made by E.I.Kats and V.V.Lebedev [arXiv:1407.4298] on our recent work "Thermodynamics of quantum crystalline membranes" [Phys. Rev. B 89, 224307 (2014)]. Kats and Lebedev question the validity of the calculation presented in our work, in particular on the use of a Debye momentum as a ultra-violet regulator for the theory. We address and counter argue the criticisms made by Kats and Lebedev to our work.Comment: 5 pages, 4 figure

Noncommutative Particles in Curved Spaces

We present a formulation in a curved background of noncommutative mechanics, where the object of noncommutativity $\theta^{\mu\nu}$ is considered as an independent quantity having a canonical conjugate momentum. We introduced a noncommutative first-order action in D=10 curved spacetime and the covariant equations of motions were computed. This model, invariant under diffeomorphism, generalizes recent relativistic results.Comment: 1+15 pages. Latex. New comments and results adde

Hamiltonian embedding of the massive noncommutative U(1) theory

We show that the massive noncommutative U(1) can be embedded in a gauge theory by using the BFFT Hamiltonian formalism. By virtue of the peculiar non-Abelian algebraic structure of the noncommutative massive U(1) theory, several specific identities involving Moyal commutators had to be used in order to make the embedding possible. This leads to an infinite number of steps in the iterative process of obtaining first-class constraints. We also shown that the involutive Hamiltonian can be constructed.Comment: 8 pages, Revtex (multicol

O uso do motor stirling no ensino de termodinâmica : uma estratégia metodológica

Neste trabalho propomos a utilização do motor Stirling de forma contextualizada, em aulas de Física, no Ensino Médio, mediante uma estratégia metodológica fundamentada na teoria de Ausubel, a partir dos subsunçores presentes na estrutura cognitiva dos estudantes. Nessa perspectiva, sugerimos uma abordagem que utilize questionamentos que possam viabilizar o ancoramento dos novos conhecimentos nos referidos subsunçores, tornando-os mais elaborados. Com isso, acreditamos que essa estratégia pode facilitar a aprendizagem significativa do ciclo de Carnot, bem como o tratamento dos aspectos sócio-ambientais relacionados ao motor Stirling

O uso do motor stirling no ensino de termodinâmica : uma estratégia metodológica

Neste trabalho propomos a utilização do motor Stirling de forma contextualizada, em aulas de Física, no Ensino Médio, mediante uma estratégia metodológica fundamentada na teoria de Ausubel, a partir dos subsunçores presentes na estrutura cognitiva dos estudantes. Nessa perspectiva, sugerimos uma abordagem que utilize questionamentos que possam viabilizar o ancoramento dos novos conhecimentos nos referidos subsunçores, tornando-os mais elaborados. Com isso, acreditamos que essa estratégia pode facilitar a aprendizagem significativa do ciclo de Carnot, bem como o tratamento dos aspectos sócio-ambientais relacionados ao motor Stirling

HERA-B Framework for Online Calibration and Alignment

This paper describes the architecture and implementation of the HERA-B framework for online calibration and alignment. At HERA-B the performance of all trigger levels, including the online reconstruction, strongly depends on using the appropriate calibration and alignment constants, which might change during data taking. A system to monitor, recompute and distribute those constants to online processes has been integrated in the data acquisition and trigger systems.Comment: Submitted to NIM A. 4 figures, 15 page