Cosmology and gravitation

Abstract

This is a brief summary with comments on selected contributions to the Cosmology and Gravitation section at the 24 th Brazilian Meeting on Particle and Fields (ENFPC XXIV), held at Caxambu, from September 30 to October 4, 2003. History and TrendsThe earliest known publication on Einstein' During this period we have grown to approximately 150 researchers in that area, scattered through almost all states of Brazil. The present meeting counted with a total of 84 contributions in CGR alone, including two invited plenary talks, three parallel presentations, 20 short oral communications and 59 poster presentations. Here we present a sampled analysis of these contributions, assembled in just a few categories.There is a noticeable tendency towards cosmology, with 53 contributions, against a only 31 from topics in local gravitation, a clear demonstration of a new trend. This is hardly surprising, considering the present status of cosmology as a highly experimental and interdisciplinary part of physics, which has provided us with a vast and challenging collection of data waiting for explanations.Therefore, it is also no surprise that the two invited plenary talks on CGR were on the main experimental results of observational cosmology, the accelerated expansion and the cosmic background radiation (CMBR). After reviewing the present observational situation, it was pointed out that those results confirm previous measurements of the COBE satellite and more recent balloon and ground-based experiments, but evidenced a deficit of fluctuation power on the largest scales, and also a variation of the spectral index in the primordial perturbation. In his own conclusion, "these measurements have confirmed the parameters of the current 'concordance model' of the Universe, but with some intriguing pointers towards 'new physics' " [4].The second plenary talk by Jerome Martin (Inst. d'Astrophysique de Paris) Inflation and Precision Cosmology, reviewed the inflationary mechanism in cosmology and its consequences to the CMBR anisotropy and formation of large scale structures. The predictions of inflationary theoretical models were compared with the WMAP data, showing an agreement between them. The talk also included an interesting discussion on the trans-Planckian problem of inflation. That is, the fact that all the scales of astrophysical relevance today were, at the beginning of inflation, smaller than the Planck length. Finally, possible observational signatures, in particular in the CMBR anisotropies, leading to topological definitions were also discussed [5].These two talks have set the background for the great majority of the discussions on Cosmology during the meeting. Therefore, it is natural to start with cosmology, moving towards the local aspects of gravitation.

Naturalness Bounds on Dipole Moments from New Physics

“…In spite of its splendor of the phenomenological successes, the standard model of the elementary particles still leaves unanswered many fundamental questions, such as the origin of the quark-lepton generations, the curious pattern of their mass spectrum, and the unnatural fine tuning in the Higgs mass renormalization [1]. People expect that some new physics at some near-by high energy scale, such as compositeness [2], broken supersymmetry [3], extra dimensions [4], or brane worlds [5], would open ways to resolve these problems. At its early stage, signatures of the new physics might reveal themselves through effective non-renormalizable interactions such as anomalous magnetic moments [6]- [10] and electric dipole moments [11].…”