Discussing direct search of dark matter particles in the Minimal Supersymmetric extension of the Standard Model with light neutralinos

We examine the status of light neutralinos in an effective Minimal Supersymmetric extension of the Standard Model (MSSM) at the electroweak scale which was considered in the past and discussed in terms of the available data of direct searches for dark matter (DM) particles. Our reanalysis is prompted by new measurements at the Tevatron and B-factories which might potentially provide significant constraints on the MSSM model. Here we examine in detail all these new data and show that the present published results from the Tevatron and B-factories have only a mild effect on the original light neutralino population. This population, which fits quite well the DAMA/LIBRA annual modulation data, would also agree with the preliminary results of CDMS, CoGeNT and CRESST, should these data, which are at present only hints or excesses of events over the expected backgrounds, be interpreted as authentic signals of DM. For the neutralino mass we find a lower bound of 7-8 GeV. Our results differ from some recent conclusions by other authors because of a few crucial points which we try to single out and elucidate.Comment: 23 pages, 25 figures, typeset with ReVTeX4. One short section on indirect searches and a few references added. A version of the paper with full resolution figures can be found at http://www.to.infn.it/~scopel/light_2010.pd

Street Viewer: An Autonomous Vision Based Traffic Tracking System

The development of intelligent transportation systems requires the availability of both accurate traffic information in real time and a cost-effective solution. In this paper, we describe Street Viewer, a system capable of analyzing the traffic behavior in different scenarios from images taken with an off-the-shelf optical camera. Street Viewer operates in real time on embedded hardware architectures with limited computational resources. The system features a pipelined architecture that, on one side, allows one to exploit multi-threading intensively and, on the other side, allows one to improve the overall accuracy and robustness of the system, since each layer is aimed at refining for the following layers the information it receives as input. Another relevant feature of our approach is that it is self-adaptive. During an initial setup, the application runs in learning mode to build a model of the flow patterns in the observed area. Once the model is stable, the system switches to the on-line mode where the flow model is used to count vehicles traveling on each lane and to produce a traffic information summary. If changes in the flow model are detected, the system switches back autonomously to the learning mode. The accuracy and the robustness of the system are analyzed in the paper through experimental results obtained on several different scenarios and running the system for long periods of time

Minimal Dark Matter

A few multiplets that can be added to the SM contain a lightest neutral component which is automatically stable and provides allowed DM candidates with a non-standard phenomenology. Thanks to coannihilations, a successful thermal abundance is obtained for well defined DM masses. The best candidate seems to be a SU(2)_L fermion quintuplet with mass 4.4 TeV, accompanied by a charged partner 166 MeV heavier with life-time 1.8 cm, that manifests at colliders as charged tracks disappearing in pi^\pm with 97.7% branching ratio. The cross section for usual NC direct DM detection is sigma_SI = f^2 1.0 10^-43 cm^2 where f ~ 1 is a nucleon matrix element. We study prospects for CC direct detection and for indirect detection.Comment: 16 pages, 2 figures. (v2: comments added, details of DM freeze-out compared with hep-ph/0601041, such that our revised version agrees with their revised version. v3: reference and comment on direct detection added, v3 matches published version in NPB. v4: some misprints in equations corrected.

Overview of the Soluble and Membrane-bound Tumor Factors Limiting NKmediated Immune Surveillance

Many evidences suggest that NK cells are effective in patrolling for and eliminating tumors in their onset phase, but hardly limit the progression of large established solid tumors. Beside the transition of tumor cells towards a more aggressive phenotype, the NK cell efficacy might be limited by a complex immunosuppressive milieu present in the tumor microenvironment. Indeed, different mechanisms damping NK cell function have been shown in these last years. These include a plethora of tumor-derived immunomodulatory soluble factors (TGF-\u3b2, MIF, adenosine, LKynurenin, PGE2) as well as soluble ligands (MICA, ULBP-2, PVR, B7-H6) that compete with membrane-bound tumor ligands for binding to activating NK receptors. During NK-tumor cell contact the NK cell function can also be inhibited by the engagement on NK cells of different inhibitory receptors. The specific ligands might be either constitutively expressed at the tumor cell surface (HLA-I, B7-H3, PVR) or de novo induced/up-regulated (PD-Ls) by immunostimulatory factors (IFN-\u3b3, TNF-\u3b1). These are largely released during the active phases of the immune responses and exert an unwanted side effect called \u201ctumor adaptive immune resistance\u201d. This review aims to summarize the best-known molecular mechanisms that, at various times and in different ways, can limit the efficacy of the NK-mediated immune surveillance of tumors