1,138 research outputs found

    A note about the t`Hooft`s ansatz for SU(N) real time guage theories

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    The t`Hooft's ansatz reduces the classical Yang--Mills theory to the λϕ4\lambda\phi^4 one. It is shown that in the frame of this ansatz the real-time classical solutions for the arbitrary SU(N) gauge group is obtained by embedding SU(2)×SU(2)SU(2)\times SU(2) into SU(N). It is argued that this group structure is the only possibility in the frame of the considered ansatz. New explicit solutions for SU(3) and SU(5) gauge groups are shown

    Unveiling Neutrino Mixing and Leptonic CP Violation

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    We review the present understanding of neutrino masses and mixings, discussing what are the unknowns in the three family oscillation scenario. Despite the anticipated success coming from the planned long baseline neutrino experiments in unraveling the leptonic mixing sector, there are two important unknowns which may remain obscure: the mixing angle θ13\theta_{13} and the CP-phase δ\delta. The measurement of these two parameters has led us to consider the combination of superbeams and neutrino factories as the key to unveil the neutrino oscillation picture.Comment: Invited brief review, 18 pages, 6 figure

    Likelihood-ratio ranking of gravitational-wave candidates in a non-Gaussian background

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    We describe a general approach to detection of transient gravitational-wave signals in the presence of non-Gaussian background noise. We prove that under quite general conditions, the ratio of the likelihood of observed data to contain a signal to the likelihood of it being a noise fluctuation provides optimal ranking for the candidate events found in an experiment. The likelihood-ratio ranking allows us to combine different kinds of data into a single analysis. We apply the general framework to the problem of unifying the results of independent experiments and the problem of accounting for non-Gaussian artifacts in the searches for gravitational waves from compact binary coalescence in LIGO data. We show analytically and confirm through simulations that in both cases the likelihood ratio statistic results in an improved analysis.Comment: 10 pages, 6 figure

    Reconstructing the calibrated strain signal in the Advanced LIGO detectors

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    Advanced LIGO's raw detector output needs to be calibrated to compute dimensionless strain h(t). Calibrated strain data is produced in the time domain using both a low-latency, online procedure and a high-latency, offline procedure. The low-latency h(t) data stream is produced in two stages, the first of which is performed on the same computers that operate the detector's feedback control system. This stage, referred to as the front-end calibration, uses infinite impulse response (IIR) filtering and performs all operations at a 16384 Hz digital sampling rate. Due to several limitations, this procedure currently introduces certain systematic errors in the calibrated strain data, motivating the second stage of the low-latency procedure, known as the low-latency gstlal calibration pipeline. The gstlal calibration pipeline uses finite impulse response (FIR) filtering to apply corrections to the output of the front-end calibration. It applies time-dependent correction factors to the sensing and actuation components of the calibrated strain to reduce systematic errors. The gstlal calibration pipeline is also used in high latency to recalibrate the data, which is necessary due mainly to online dropouts in the calibrated data and identified improvements to the calibration models or filters.Comment: 20 pages including appendices and bibliography. 11 Figures. 3 Table

    Measuring CP violation and mass ordering in joint long baseline experiments with superbeams

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    We propose to measure the CP phase δCP\delta_{\rm CP}, the magnitude of the neutrino mixing matrix element Ue3|U_{e3}| and the sign of the atmopheric scale mass--squared difference Δm312\Delta{\rm m}^2_{31} with a superbeam by the joint analysis of two different long baseline neutrino oscillation experiments. One is a long baseline experiment (LBL) at 300 km and the other is a very long baseline (VLBL) experiment at 2100 km. We take the neutrino source to be the approved high intensity proton synchrotron, HIPA. The neutrino beam for the LBL is the 2-degree off-axis superbeam and for the VLBL, a narrow band superbeam. Taking into account all possible errors, we evaluate the event rates required and the sensitivities that can be attained for the determination of δCP\delta_{\rm CP} and the sign of Δm312\Delta m^2_{31}. We arrive at a representative scenario for a reasonably precise probe of this part of the neutrino physics.Comment: 25 RevTEX pages, 16 PS figures, revised figure captions and references adde

    Children Rights and Global Citizenship: an Approach from the educational Community

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    La Convención de los Derechos del Niño (CDN) es una herramienta fundamental para la educación de niños, niñas y adolescentes. Ésta debe entenderse como el marco de referencia universal que contribuye a formar niños y niñas capacitados para ejercer sus derechos de ciudadanía. Sin embargo, conocemos muy poco sobre cómo los derechos de la infancia y la ciudadanía global se integran en el sistema educativo español. El objetivo de este trabajo es identificar las necesidades formativas que tiene la comunidad educativa en relación a la CDN desde las dimensiones cognitiva, metodológica y actitudinal. Se trata de una investigación cualitativa que ha contado con la participación de 124 personas representantes de la comunidad educativa (alumnado, docentes, padres y madres) distribuidas en 14 grupos de discusión desarrollados en 11 Comunidades Autónomas del territorio español. El análisis de contenido muestra la escasa incorporación en los centros escolares de la CDN, así como una la visión parcial de ésta por parte de los integrantes de la comunidad educativa. Se observan necesidades en la falta de estrategias de enseñanza-aprendizaje que fomenten la autonomía y la participación infantil en el aula y el centro. Finalmente, se observa la dificultad de posicionar a la infancia como sujeto de derechos con facultades para ejercer su ciudadanía.Esta investigación ha sido posible gracias a la financiación de la Agencia Española de Cooperación Internacional para el Desarrollo (AECID) y de UNICEF – Comité Español, en el marco del proyecto “Fomento de la Educación para el Desarrollo en la Educación Formal” 2010 – 2012. El contenido de esta publicación es responsabilidad exclusiva de los autores y no refleja necesariamente la opinión de la AECID

    Recovery from chronic fatigue syndrome after treatments given in the PACE trial

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    BACKGROUND: A multi-centre, four-arm trial (the PACE trial) found that rehabilitative cognitive behaviour therapy (CBT) and graded exercise therapy (GET) were more effective treatments for chronic fatigue syndrome (CFS) than specialist medical care (SMC) alone, when each was added to SMC, and more effective than adaptive pacing therapy (APT) when added to SMC. In this study we compared how many participants recovered after each treatment. METHOD: We defined recovery operationally using multiple criteria, and compared the proportions of participants meeting each individual criterion along with two composite criteria, defined as (a) recovery in the context of the trial and (b) clinical recovery from the current episode of the illness, however defined, 52 weeks after randomization. We used logistic regression modelling to compare treatments. RESULTS: The percentages (number/total) meeting trial criteria for recovery were 22% (32/143) after CBT, 22% (32/143) after GET, 8% (12/149) after APT and 7% (11/150) after SMC. Similar proportions met criteria for clinical recovery. The odds ratio (OR) for trial recovery after CBT was 3.36 [95% confidence interval (CI) 1.64–6.88] and for GET 3.38 (95% CI 1.65–6.93), when compared to APT, and after CBT 3.69 (95% CI 1.77–7.69) and GET 3.71 (95% CI 1.78–7.74), when compared to SMC (p values < or =0.001 for all comparisons). There was no significant difference between APT and SMC. Similar proportions recovered in trial subgroups meeting different definitions of the illness. CONCLUSIONS: This study confirms that recovery from CFS is possible, and that CBT and GET are the therapies most likely to lead to recovery

    A Beta Beam complex based on the machine upgrades for the LHC

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    The Beta Beam CERN design is based on the present LHC injection complex and its physics reach is mainly limited by the maximum rigidity of the SPS. In fact, some of the scenarios for the machine upgrades of the LHC, particularly the construction of a fast cycling 1 TeV injector (``Super-SPS''), are very synergic with the construction of a higher γ\gamma Beta Beam. At the energies that can be reached by this machine, we demonstrate that dense calorimeters can already be used for the detection of ν\nu at the far location. Even at moderate masses (40 kton) as the ones imposed by the use of existing underground halls at Gran Sasso, the CP reach is very large for any value of θ13\theta_{13} that would provide evidence of νe\nu_e appearance at T2K or NOν\nuA (θ133\theta_{13}\geq 3^\circ). Exploitation of matter effects at the CERN to Gran Sasso distance provides sensitivity to the neutrino mass hierarchy in significant areas of the θ13δ\theta_{13}-\delta plane
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