Quantum Numbers for Excitations of Bose-Einstein Condensates in 1D Optical Lattices

The excitation spectrum and the band structure of a Bose-Einstein condensate in a periodic potential are investigated. Analyses within full 3D systems, finite 1D systems, and ideal periodic 1D systems are compared. We find two branches of excitations in the spectra of the finite 1D model. The band structures for the first and (part of) the second band are compared between a finite 1D and the fully periodic 1D systems, utilizing a new definition of a effective wavenumber and a phase-slip number. The upper and lower edges of the first gap coincide well between the two cases. The remaining difference is explained by the existence of the two branches due to the finite-size effect.Comment: 5 pages, 9 figure

Long-time behaviour and phase transitions for the McKean—Vlasov equation on the torus

We study the McKean-Vlasov equation ∂t% = β −1∆% + κ ∇·(%∇(W ? %)) , with periodic boundary conditions on the torus. We first study the global asymptotic stability of the homogeneous steady state. We then focus our attention on the stationary system, and prove the existence of nontrivial solutions branching from the homogeneous steady state, through possibly infinitely many bifurcations, under appropriate assumptions on the interaction potential. We also provide sufficient conditions for the existence of continuous and discontinuous phase transitions. Finally, we showcase these results by applying them to several examples of interaction potentials such as the noisy Kuramoto model for synchronisation, the Keller–Segel model for bacterial chemotaxis, and the noisy Hegselmann–Krausse model for opinion dynamics

Communication: Improving the density functional theoryU description of CeO 2 by including the contribution of the O 2p electrons

Density functional theory (DFT) based approaches within the local-density approximation or generalized gradient approximation frameworks fail to predict the correct electron localization in strongly correlated systems due to the lack of cancellation of the Coulomb self-interaction. This problem might be circumvented either by using hybrid functionals or by introducing a Hubbard-like term to account for the on site interactions. This latter DFTU approach is less expensive and therefore more practical for extensive calculations in solid-state computational simulations. By and large, the U term only affects the metal electrons, in our case the Ce 4f ones. In the present work, we report a systematic analysis of the effect of adding such a U term also to the oxygen 2p electrons. We find that using a set of U f 5 eV and U p 5eV effective terms leads to improved description of the lattice parameters, band gaps, and formation and reduction energies of CeO

Stochastic dynamics of an electron in a Penning trap: phase flips correlated with amplitude collapses and revivals

We study the effect of noise on the axial mode of an electron in a Penning trap under parametric-resonance conditions. Our approach, based on the application of averaging techniques to the description of the dynamics, provides an understanding of the random phase flips detected in recent experiments. The observed correlation between the phase jumps and the amplitude collapses is explained. Moreover, we discuss the actual relevance of noise color to the identified phase-switching mechanism. Our approach is then generalized to analyze the persistence of the stochastic phase flips in the dynamics of a cloud of N electrons. In particular, we characterize the detected scaling of the phase-jump rate with the number of electrons.Comment: 15 pages, 6 figure

Supersymmetric Dirac-Born-Infeld theory in noncommutative space

We present a supersymmetric version of Dirac-Born-Infeld (DBI) theory in noncommutative space-time, both for Abelian and non-Abelian gauge groups. We show, using the superfield formalism, that the definition of a certain ordering with respect to the * product leads naturally to a DBI action both in the U(1) as well as in the U(N) case. BPS equations are analysed in this context and properties of the resulting theory are discussed.Comment: 16 pages, no figure

Constraints on B and Higgs Physics in Minimal Low Energy Supersymmetric Models

We study the implications of minimal flavor violating low energy supersymmetry scenarios for the search of new physics in the B and Higgs sectors at the Tevatron collider and the LHC. We show that the already stringent Tevatron bound on the decay rate B_s -> mu+ mu- sets strong constraints on the possibility of generating large corrections to the mass difference Delta M_s of the B_s eigenstates. We also show that the B_s -> mu+ mu- bound together with the constraint on the branching ratio of the rare decay b -> s gamma has strong implications for the search of light, non-standard Higgs bosons at hadron colliders. In doing this, we demonstrate that the former expressions derived for the analysis of the double penguin contributions in the Kaon sector need to be corrected by additional terms for a realistic analysis of these effects. We also study a specific non-minimal flavor violating scenario, where there are flavor changing gluino-squark-quark interactions, governed by the CKM matrix elements, and show that the B and Higgs physics constraints are similar to the ones in the minimal flavor violating case. Finally we show that, in scenarios like electroweak baryogenesis which have light stops and charginos, there may be enhanced effects on the B and K mixing parameters, without any significant effect on the rate of B_s -> mu+ mu-.Comment: 40 pages, 14 figures; added references and note about recent measurement

China and Latin America: Extractive industries, foreign politics and integration

En esta ocasión, la Revista Andina de Estudios Políticos presenta su sexto volumen, el cual trae un Dossier especial sobre el estado actual de las relaciones entre China y América Latina. Este número de la RAEP fue hecho en el marco de las actividades que el Instituto de Estudios Políticos Andinos viene realizando con la Comunidad de Estudios Chinos y Latinoamericanos de Beijing (CECLA), el cual se inserta dentro de la amplia producción bibliográfica que se viene dando en torno al carácter del llamado ‘ascenso’ (también llamado ‘regreso’) de China a la arena internacional como actor de primer orden. No hay ninguna zona geográfica del mundo que no haya sido afectada por este proceso, por lo que hay un interés cada vez mayor por parte de Gobiernos, think-tanks, Universidades y Centros de Investigación en general.On this occasion, the Andean Magazine of Political Studies presents its sixth volume, which brings a special Dossier on the current state of relations between China and Latin America. This number of the RAEP was made in the framework of the activities that the Institute of Andean Political Studies has been carrying out with the Community of Chinese and Latin American Studies of Beijing (CECLA), which is inserted within the wide bibliographic production that is taking place around the character of China's so-called 'rise' (also called 'return') to the international arena as a leading actor. There is no geographical area in the world that has not been affected by this process, so there is a growing interest on the part of Governments, think tanks, Universities and Research Centers in general