Latest Results on the Hot-Dense Partonic Matter at RHIC

At the Relativistic Heavy Ion Collider (RHIC) collisions of heavy ions at nucleon-nucleon energies of 200 GeV appear to have created a new form of matter thought to be a deconfined state of the partons that ordinarily are bound in nucleons.We discuss the evidence that a thermalized partonic medium, usually called a Quark Gluon Plasma (QGP), has been produced. Then we discuss the effect of this high-density medium on the production of jets and their pair correlations. Next we look at direct photons as a clean electro-magnetic probe to constrain the initial hard scatterings. Finally we review the developing picture for the effect of this medium on the production of open heavy quarks and on the screening by the QGP of heavy-quark bound states.Comment: 6 pages, 14 figures, proceedings for QNP06 (5-10 June, 2006) invited tal

Finite cosmology and a CMB cold spot

The standard cosmological model posits a spatially flat universe of infinite extent. However, no observation, even in principle, could verify that the matter extends to infinity. In this work we model the universe as a finite spherical ball of dust and dark energy, and obtain a lower limit estimate of its mass and present size: the mass is at least 5 x 10^23 solar masses and the present radius is at least 50 Gly. If we are not too far from the dust-ball edge we might expect to see a cold spot in the cosmic microwave background, and there might be suppression of the low multipoles in the angular power spectrum. Thus the model may be testable, at least in principle. We also obtain and discuss the geometry exterior to the dust ball; it is Schwarzschild-de Sitter with a naked singularity, and provides an interesting picture of cosmogenesis. Finally we briefly sketch how radiation and inflation eras may be incorporated into the model.Comment: 20 pages, 12 figure

Weyl Geometry as Characterization of Space-Time

Motivated by an axiomatic approach to characterize space-time it is investigated a reformulation of Einstein's gravity where the pseudo-riemannian geometry is substituted by a Weyl one. It is presented the main properties of the Weyl geometry and it is shown that it gives extra contributions to the trajectories of test particles, serving as one more motivation to study general relativity in Weyl geometry. It is introduced its variational formalism and it is established the coupling with other physical fields in such a way that the theory acquires a gauge symmetry for the geometrical fields. It is shown that this symmetry is still present for the red-shift and it is concluded that for cosmological models it opens the possibility that observations can be fully described by the new geometrical scalar field. It is concluded then that this reformulation, although representing a theoretical advance, still needs a complete description of their objects.Comment: 12 page

Evaluation of The Forgiveness project within prisons

The Forgiveness Project (TFP) is a UK based charity that uses real stories to explore how ideas around forgiveness, reconciliation and conflict resolution can have a positive impact on people’s lives. One aspect of the charity’s work is a programme run within prisons, targeted at the early stages of a sentence. TFP describe their prison programme as an intensive, group based intervention that encourages prisoners to explore concepts of forgiveness and reparation in a framework that fosters greater accountability and responsibility. Every course is co-facilitated by at least one ex-offender and a victim/survivor of serious crime. The intervention can be seen as being restorative and preparatory; those who take part in the programme will tend to be relatively early on in their sentence. TFP centres on the personal testimonies of both victims and perpetrators of crime and violence. TFP is unlike many other restorative initiatives in that it has no political or religious affiliation and TFP’s prison programme is similarly secular in its approach. TFP aims to facilitate changes in attitude and thinking styles of offenders. That is, to encourage prisoners and young offenders in finding their own pathways to change. In finding those pathways, they may draw on many different resources and insights. These could include personal, communal, spiritual or religious beliefs that they may have, whether or not they have previously seen those beliefs as relevant to their offending behaviours. TFP run programmes via both education and psychology units. The emphasis on individual change is also intended to differentiate TFP from prison or National Offenders Management Service interventions. This person centred, facilitative but non prescriptive approach was adopted with the intention that prisoners and young offenders would be more responsive to the intervention than they may be to other, more standardised, manual based programmes. This report of a research study by Dr Joanna Adler and Mansoor Mir of Forensic Psychological Services at Middlesex University into the effectiveness of TFP presents quantitative and qualitative findings, and concludes overall that TFP is well received by prisoners and staff, potentially has an impact on recidivism and does well to stimulate insight and bring about change. The report ends with some recommendations to increase capacity and sustainability

Kowalevski's analysis of the swinging Atwood's machine

We study the Kowalevski expansions near singularities of the swinging Atwood's machine. We show that there is a infinite number of mass ratios $M/m$ where such expansions exist with the maximal number of arbitrary constants. These expansions are of the so--called weak Painlev\'e type. However, in view of these expansions, it is not possible to distinguish between integrable and non integrable cases.Comment: 30 page

Correction-to-scaling exponent for two-dimensional percolation

We show that the correction-to-scaling exponents in two-dimensional percolation are bounded by Omega <= 72/91, omega = D Omega <= 3/2, and Delta_1 = nu omega <= 2, based upon Cardy's result for the critical crossing probability on an annulus. The upper bounds are consistent with many previous measurements of site percolation on square and triangular lattices, and new measurements for bond percolation presented here, suggesting this result is exact. A scaling form evidently applicable to site percolation is also found

Brane Effects on Extra Dimensional Scenarios: A Tale of Two Gravitons

We analyze the propagation of a scalar field in multidimensional theories which include kinetic corrections in the brane, as a prototype for gravitational interactions in a four dimensional brane located in a (nearly) flat extra dimensional bulk. We regularize the theory by introducing an infrared cutoff given by the size of the extra dimensions and a physical ultraviolet cutoff of the order of the fundamental Planck scale in the higher dimensional theory. We show that, contrary to recent suggestions, the radius of the extra dimensions cannot be arbitrarily large. Moreover, for finite radii, the gravitational effects localized on the brane can substantially alter the phenomenology of collider and/or table-top gravitational experiments. This phenomenology is dictated by the presence of a massless graviton, with standard couplings to the matter fields, and a massive graviton which couples to matter in a much stronger way. While graviton KK modes lighter than the massive graviton couple to matter in a standard way, the couplings to matter of the heavier KK modes are strongly suppressed.Comment: 21 pages, latex2e, axodraw.sty, 2 figure

Direct photons in d+Au collisions at s_(NN)**(1/2)=200GeV with STAR

Results are presented of an ongoing analysis of direct photon production in s_(NN)=200GeV deuteron-gold collisions with the STAR experiment at RHIC. A significant excess of direct photons is observed near mid-rapidity 0<y<1 and found to be consistent with next-to-leading order pQCD calculations including the contribution from fragmentation photons.Comment: 4 pages, 4 figures, HotQuarks 200

Billiard algebra, integrable line congruences, and double reflection nets

The billiard systems within quadrics, playing the role of discrete analogues of geodesics on ellipsoids, are incorporated into the theory of integrable quad-graphs. An initial observation is that the Six-pointed star theorem, as the operational consistency for the billiard algebra, is equivalent to an integrabilty condition of a line congruence. A new notion of the double-reflection nets as a subclass of dual Darboux nets associated with pencils of quadrics is introduced, basic properies and several examples are presented. Corresponding Yang-Baxter maps, associated with pencils of quadrics are defined and discussed.Comment: 18 pages, 8 figure