Investigation of Quantum Phase Transitions using Multi-target DMRG Methods

In this paper we examine how the predictions of conformal invariance can be widely exploited to overcome the difficulties of the density-matrix renormalization group near quantum critical points. The main idea is to match the set of low-lying energy levels of the lattice Hamiltonian, as a function of the system's size, with the spectrum expected for a given conformal field theory in two dimensions. As in previous studies this procedure requires an accurate targeting of various excited states. Here we discuss how this can be achieved within the DMRG algorithm by means of the recently proposed Thick-restart Lanczos method. As a nontrivial benchmark we use an anisotropic spin-1 Hamiltonian with special attention to the transitions from the Haldane phase. Nonetheless, we think that this procedure could be generally valid in the study of quantum critical phenomena.Comment: 14 pages, LaTeX2e (svjour class), 8 EPS figures. Same version as the published one, with new references and English corrections of the proofreade

Image rights: Exploitation and legal control in English and Hungarian law

In the past decades due to changed technical advances, features of the personality have become economically exploitable to an extent not previously known. Pop stars, TV celebrities as well as famous athletes have sought protection against the commercial use of their images, names and likenesses without their consent.1 Despite the economic value of personality and image rights, there is currently no international standard or agreed legal concept for recognising an image right. While many jurisdictions, for example, the US, Germany, France and Hungary offer express statutory protection against the unauthorised commercial use of an individual’s image by a third party in the context of publicity or personality rights, English law provides no cause of action for the infringement of image rights as such. Although a celebrity may currently obtain protection through various statutory and common law rights, such as the developing law of privacy, trade mark law breach of confidence and, in particular, the tort of passing off, none of these rights were designed to protect image or personality rights.2 In this context, this article explores the potentially enforceable rights, their benefits and practical strategies to protect name and image rights in the UK3 and Hungary