Some comments on the universal constant in DSR

Deformed Special Relativity is usually presented as a deformation of Special Relativity accommodating a new universal constant, the Planck mass, while respecting the relativity principle. In order to avoid some fundamental problems (e.g. soccer ball problem), we argue that we should switch point of view and consider instead the Newton constant $G$ as the universal constant.Comment: 12 pages, Proceedings of DICE2006 (Piombino, Italy

The traitor as patriot : Guy Burgess, Englishness and camp in Another Country and An Englishman Abroad

This article focuses on the representation of the spy Guy Burgess, one of the famous Cambridge ring, in two very successful British heritage films, An Englishman Abroad (John Schlesinger, UK, 1983) and Another Country (Marek Kanievska, UK, 1984). The article argues that the films rely on popular notions of Englishness as politically safe and non-extremist, thus fabricating a view of the past that misrepresents Burgess in the effort to normalize him. Similarly, stereotypical views of gay men as frivolous and non-ideological are amply exploited in the films' portrayal of their protagonist. Burgess's upper-class English roots are used to package him as part of the heritage experience, while his homosexuality is not only presented as the reason for spying, but it is also constructed as a camp performance, effectively defusing the threat of ideological commitment and political betrayal. The radical, lethal and devoutly Marxist Burgess is thus stripped of his ideology and turned into a safe national icon.Publisher PDFPeer reviewe

Snyder Space-Time: K-Loop and Lie Triple System

Different deformations of the Poincare symmetries have been identified for various non-commutative spaces (e.g. $\kappa$-Minkowski, $sl(2,R)$, Moyal). We present here the deformation of the Poincare symmetries related to Snyder space-time. The notions of smooth "K-loop", a non-associative generalization of Abelian Lie groups, and its infinitesimal counterpart given by the Lie triple system are the key objects in the construction

Deformed symmetries from quantum relational observables

Deformed Special Relativity (DSR) is a candidate phenomenological theory to describe the Quantum Gravitational (QG) semi-classical regime. A possible interpretation of DSR can be derived from the notion of deformed reference frame. Observables in (quantum) General Relativity can be constructed from (quantum) reference frame – a physical observable is then a relation between a system of interest and the reference frame. We present a toy model and study an example of such quantum relational observables. We show how the intrinsic quantum nature of the reference frame naturally leads to a deformation of the symmetries, comforting DSR to be a good candidate to describe the QG semi-classical regime

Non-Commutativity of Effective Space-Time Coordinates and the Minimal Length

Considering that a position measurement can effectively involve a momentum-dependent shift and rescaling of the "true" space-time coordinates, we construct a set of effective space-time coordinates which are naturally non-commutative. They lead to a minimum length and are shown to be related to Snyder's coordinates and the five-dimensional formulation of Deformed Special Relativity. This effective approach then provides a natural physical interpretation for both the extra fifth dimension and the deformed momenta appearing in this context.Comment: 5 page

Scalar field theory in Snyder space-time: alternatives

We construct two types of scalar field theory on Snyder space-time. The first one is based on the natural momenta addition inherent to the coset momentum space. This construction uncovers a non-associative deformation of the Poincar\'e symmetries. The second one considers Snyder space-time as a subspace of a larger non-commutative space. We discuss different possibilities to restrict the extra-dimensional scalar field theory to a theory living only on Sndyer space-time and present the consequences of these restrictions on the Poincar\'e symmetries. We show moreover how the non-associative approach and the Doplicher-Fredenhagen-Roberts space can be seen as specific approximations of the extra-dimensional theory. These results are obtained for the 3d Euclidian Snyder space-time constructed from \SO(3,1)/\SO(3), but our results extend to any dimension and signature.Comment: 24 pages

Physics of Deformed Special Relativity

In many different ways, Deformed Special Relativity (DSR) has been argued to provide an effective limit of quantum gravity in almost-flat regime. Unfortunately DSR is up to now plagued by many conceptual problems (in particular how it describes macroscopic objects) which forbids a definitive physical interpretation and clear predictions. Here we propose a consistent framework to interpret DSR. We extend the principle of relativity: the same way that Special Relativity showed us that the definition of a reference frame requires to specify its speed, we show that DSR implies that we must also take into account its mass. We further advocate a 5-dimensional point of view on DSR physics and the extension of the kinematical symmetry from the Poincare group to the Poincare-de Sitter group (ISO(4,1)). This leads us to introduce the concept of a pentamomentum and to take into account the renormalization of the DSR deformation parameter kappa. This allows the resolution of the "soccer ball problem" (definition of many-particle-states) and provides a physical interpretation of the non-commutativity and non-associativity of the addition the relativistic quadrimomentum.Comment: 8 pages, short version of gr-qc/0412004, Proceedings of the Second International Workshop DICE2004 (Castello di Piombino, Tuscany) "From Decoherence and Emergent Classicality to Emergent Quantum Mechanics