Conserved gravitational charges, locality and the holographic Weyl anomaly - a fresh viewpoint

Since the proposal of the AdS/CFT correspondence, made by Maldacena and Witten, there has been some controversy about the definition of conserved Noether charges associated to asymptotic isometries in asymptotically AdS spacetimes, namely, whether they form an anomalous (i.e., a nontrivial central extension) representation of the Lie algebra of the conformal group in odd bulk dimensions or not. In the present work, we shall review the derivation of these charges by using covariant phase space techniques, emphasizing the principle of locality underlying it. We shall also comment on how these issues manifest themselves in the quantum setting.Comment: revtex4 format, 3 pages, no figures. Modified version of a poster presentation made at the International Conference ''100 Years of Relativity'', held at the MASP, Sao Paulo, Brazil, in August 22nd-24th, 2005. Submitted to refereeing for publication in Conference's Proceedings volume by Braz.J.Phy

Integrable quantum dynamics of open collective spin models

We consider a collective quantum spin-$s$ in contact with Markovian spin-polarized baths. Using a conserved super-operator charge, a differential representation of the Liouvillian is constructed to find its exact spectrum and eigen-modes. We study the spectral properties of the model in the large-$s$ limit using a semi-classical quantization condition and show that the spectral density may diverge along certain curves in the complex plane. We exploit our exact solution to characterize steady-state properties, in particular at the discontinuous phase transition that arises for unpolarized environments, and to determine the decay rates of coherences and populations. Our approach provides a systematic way of finding integrable Liouvillian operators with non-trivial steady-states as well as a way to study their spectral properties and eigen-modes.Comment: 5 pages, 4 figure

Many-body quantum dynamics of initially trapped systems due to a Stark potential --- thermalization vs. Bloch oscillations

We analyze the dynamics of an initially trapped cloud of interacting quantum particles on a lattice under a linear (Stark) potential. We reveal a dichotomy: initially trapped interacting systems possess features typical of both many-body-localized and self-thermalizing systems. We consider both fermions ($t$-$V$ model) and bosons (Bose-Hubbard model). For the zero and infinite interaction limits, both systems are integrable: we provide analytic solutions in terms of the moments of the initial cloud shape, and clarify how the recurrent dynamics (many-body Bloch oscillations) depends on the initial state. Away from the integrable points, we identify and explain the time scale at which Bloch oscillations decohere

Impact of CSR perceptions on workers’ innovative behaviour: exploring the social exchange process and the role of perceived external prestige

The study aims to show how organisational corporate social responsibility (CSR) can influence workers’ attitudes, especially in terms of innovative behaviour (IB). A second aim is to explore the social exchange process that may underlie this relationship, by examining the mediating role of organisational trust (OT), affective commitment (AC) and happiness (HAP), and the moderating role of perceived external prestige (PEP). The authors employ structural equation modelling based on survey data obtained from 315 Portuguese individuals. The findings show that perceptions of CSR predict IB through a social exchange process which involves the mediating role of OT, AC and HAP and the moderating process of PEP. They suggest that managers should implement CSR practices because these can contribute towards fostering IB, but that they should also invest in communication and in the process of upgrading corporate image. This study enriches the existing knowledge about social exchange relationships in organisational contexts, and responds to the need to understand underlying mechanisms linking CSR with workers’ organisational outcomes, by analysing CSR practices from a holistic stakeholder perspective.info:eu-repo/semantics/publishedVersio

Strongly interacting bosons in multi-chromatic potentials supporting mobility edges: localization, quasi-condensation and expansion dynamics

We provide an account of the static and dynamic properties of hard-core bosons in a one-dimensional lattice subject to a multi-chromatic quasiperiodic potential for which the single-particle spectrum has mobility edges. We use the mapping from strongly interacting bosons to weakly interacting fermions, and provide exact numerical results for hard-core bosons in and out of equilibrium. In equilibrium, we find that the system behaves like a quasi-condensate (insulator) depending on whether the Fermi surface of the corresponding fermionic system lies in a spectral region where the single-particle states are delocalized (localized). We also study non-equilibrium expansion dynamics of initially trapped bosons, and demonstrate that the extent of partial localization is determined by the single-particle spectrum