Sterile neutrinos as subdominant warm dark matter

In light of recent findings which seem to disfavor a scenario with (warm) dark matter entirely constituted of sterile neutrinos produced via the Dodelson-Widrow (DW) mechanism, we investigate the constraints attainable for this mechanism by relaxing the usual hypothesis that the relic neutrino abundance must necessarily account for all of the dark matter. We first study how to reinterpret the limits attainable from X-ray non-detection and Lyman-alpha forest measurements in the case that sterile neutrinos constitute only a fraction fs of the total amount of dark matter. Then, assuming that sterile neutrinos are generated in the early universe solely through the DW mechanism, we show how the X-ray and Lyman-alpha results jointly constrain the mass-mixing parameters governing their production. Furthermore, we show how the same data allow us to set a robust upper limit fs < 0.7 at the 2 sigma level, rejecting the case of dominant dark matter (fs = 1) at the ~ 3 sigma level.Comment: Minor changes; added references; version accepted for publication in Phys. Rev.

The NASA-JAXA Global Precipitation Measurement mission – part I: New frontiers in precipitation

The Global Precipitation Measurement (GPM) Core Observatory measuring over a mid-latitude storm. The red, white, magenta, maroon and blue lines indicate the flight path, satellite altitude, GPM Microwave Imager swath, Dual-frequency Precipitation Radar (DPR) Ku-band (KuPR) swath and DPR Ka-band (KaPR) swath, respectively. The rainfall is heaviest where red and lightest where dark blue; 3-dimensional measurements are only available from the DPR segment of the swath. Credit: NASA's Goddard Space Flight Center Scientific Visualization Studio; adapted from original image

Analisi dei percorsi diagnostico terapeutico assistenziali (PDTA) regionali sulla sclerosi multipla esistenti

INTRODUZIONE La sclerosi multipla (SM) è una malattia cronica ad alta complessità che necessita l’attuazione di programmi di cura e assistenza diversificati per fase di malattia e livello di disabilità. In molte regioni e singole aziende ospedaliere/territoriali sono stati definiti/sono in corso di definizione PDTA di riferimento. Lo scopo dello studio è valutare lo stato dell’arte dei PDTA per la SM in Italia. METODI Analisi dei PDTA regionali già formalizzati e della documentazione di lavoro utilizzata per definirli. RISULTATI Ad oggi sono 6 le Regioni che hanno adottato e formalizzato PDTA regionali per la SM: Sicilia, Veneto, Toscana, Lazio, Emilia Romagna, Puglia. Analizzando i documenti regionali emergono buone prassi ma anche criticità quali differenze metodologiche, differente modalità di articolazione della rete clinica, approcci diversificati nella fissazione o meno di livelli di riferimento, attenzione differente rispetto ai temi della riabilitazione, dell’accertamento medico legale, della continuità assistenziale, dell’integrazione socio-sanitaria. Rispetto al percorso riabilitativo, solo 2 PDTA (Veneto e Sicilia) riconoscono l’importanza di definire percorsi riabilitativi di presa in carico che variano a seconda del livello di disabilità e che devono essere attivati, in ottica preventiva e di promozione della riabilitazione come cura, sin dal momento della diagnosi. CONCLUSIONI Le difformità, solo in parte giustificate dai diversi contesti organizzativi regionali e con il rischio di situazioni di forti iniquità e ineguaglianza nell'accesso alle cure e assistenza da parte dei pazienti, richiede un percorso di creazione o modifica, ove presenti, di tavoli permanenti per l’aggiornamento nel tempo dei contenuti del PDTA e il monitoraggio della concreta applicazione e declinazione delle indicazioni regionali all’interno di ospedali, centri clinici e servizi del territorio attraverso, altresì, la costruzione e l’applicazione di un set di indicatori ad hoc per la SM

Testing the Higgs Mechanism in the Lepton Sector with multi-TeV e+e- Collisions

Multi-TeV e+e- collisions provide with a large enough sample of Higgs bosons to enable measurements of its suppressed decays. Results of a detailed study of the determination of the muon Yukawa coupling at 3 TeV, based on full detector simulation and event reconstruction, are presented. The muon Yukawa coupling can be determined with a relative accuracy of 0.04 to 0.08 for Higgs bosons masses from 120 GeV to 150 GeV, with an integrated luminosity of 5 inverse-ab. The result is not affected by overlapping two-photon background.Comment: 6 pages, 2 figures, submitted to J Phys G.: Nucl. Phy

The Luminous Convolution Model as an alternative to dark matter in spiral galaxies

The Luminous Convolution Model (LCM) demonstrates that it is possible to predict the rotation curves of spiral galaxies directly from estimates of the luminous matter. We consider two frame-dependent effects on the light observed from other galaxies: relative velocity and relative curvature. With one free parameter, we predict the rotation curves of twenty-three (23) galaxies represented in forty-two (42) data sets. Relative curvature effects rely upon knowledge of both the gravitational potential from luminous mass of the emitting galaxy and the receiving galaxy, and so each emitter galaxy is compared to four (4) different Milky Way luminous mass models. On average in this sample, the LCM is more successful than either dark matter or modified gravity models in fitting the observed rotation curve data. Implications of LCM constraints on populations synthesis modeling are discussed in this paper. This paper substantially expands the results in arXiv:1309.7370.Comment: Implications of LCM constraints on populations synthesis modeling are discussed in this paper. This paper substantially expands the results in arxiv:1309.737

Spin dynamics and level structure of quantum-dot quantum wells

We have characterized CdS/CdSe/CdS quantum-dot quantum wells using time-resolved Faraday rotation (TRFR). The spin dynamics show that the electron g-factor varies as a function of quantum well width and the transverse spin lifetime of several nano-seconds is robust up to room temperature. As a function of probe energy, the amplitude of the TRFR signal shows pronounced resonances, which allow one to identify individual exciton transitions. While the TRFR data are inconsistent with the conduction and valence band level scheme of spherical quantum-dot quantum wells, a model in which broken spherical symmetry is taken into account captures the essential features.Comment: 5 pages, 3 figure

Studies of New Vector Resonances at the CLIC Multi-TeV e+e- Collider

Several models predict the existence of new vector resonances in the multi-TeV region, which can be produced in high energy e+e- collisions in the s-channel. In this paper we review the existing limits on the masses of these resonances from LEP/SLC and TEVATRON data and from atomic parity violation in some specific models. We study the potential of a multi-TeV e+e- collider, such as CLIC, for the determination of their properties and nature.Comment: 17 pages, 16 EPS figures, uses JHEP3.cl

Characterisation of Hybrid Pixel Detectors with capacitive charge division

In order to fully exploit the physics potential of the future high energy e+ e- linear collider, a Vertex Tracker providing high resolution track reconstruction is required. Hybrid pixel sensors are an attractive technology due to their fast read-out capabilities and radiation hardness. A novel pixel detector layout with interleaved cells between the readout nodes has been developed to improve the single point resolution. The results of the characterisation of the first processed prototypes are reported.Comment: 5 pages, 2 figures, presented at LCWS2000, Linear Collider Workshop, October 24-28 2000, Fermi National Accelerator Laboratory, Batavia, Illinois, U.S.A. Proceedings to be published by the American Institute of Physic

Radiative corrections to electroweak parameters in the Higgs triplet model and implication with the recent Higgs boson searches

We study radiative corrections to the electroweak parameters in the Higgs model with the Y=1 triplet field, which is introduced in the scenario of generating neutrino masses based on the so-called type II seesaw mechanism. In this model, the rho parameter deviates from unity at the tree level. Consequently, the electroweak sector of the model is described by the four input parameters such as $\alpha_{\text{em}}$, $G_F$, $m_Z$ and $\sin^2\theta_W$. We calculate the one loop contribution to the W boson mass as well as to the rho parameter in order to clarify the possible mass spectrum of the extra Higgs bosons under the constraint from the electroweak precision data. We find that the hierarchical mass spectrum among $H^{\pm\pm}$, $H^{\pm}$ and $A$ (or $H$) is favored by the precision data especially for the case of $m_A$ $(\simeq m_H)>m_{H^+}>m_{H^{++}}$, where $H^{\pm\pm}$, $H^{\pm}$, $A$ and $H$ are the doubly-charged, singly-charged, CP-odd and CP-even Higgs bosons mainly originated from the triplet field. We also discuss phenomenological consequences of such a mass spectrum with relatively large mass splitting. The decay rate of the Higgs boson decay into two photons is evaluated under the constraint from the electroweak precision data, regarding the recent Higgs boson searches at the CERN LHC.Comment: 17 pages, 23 figures, version published in PRD, title slightly modifie