3,391 research outputs found

    Search for Long-Lived Heavy Neutrinos at the LHC with a VBF Trigger

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    The charged current production of long-lived heavy neutrinos at the LHC can use a prompt charged lepton for triggering the measurement of the process. However, in order to fully characterize the heavy neutrino interactions, it is necessary to also probe Higgs or ZZ mediated neutral current production. In this case the charged lepton is not available, so other means of triggering are required. In this work, we explore the possibility of using a vector boson fusion trigger in the context of a GeV-scale Type I Seesaw model. We consider a minimal model, where both Higgs and Z-mediated contributions produce one heavy neutrino, as well as an extended model where the Higgs can decay into two heavy ones. Both scenarios are tested through displaced dilepton and displaced multitrack jet searches.Comment: 31 pages, 1 appendix, 5 figures; v2: improved version, accepted for publication in EPJ

    Testing the goodness of fit of a hilbertian autoregressive model

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    The presented methodology for testing the goodness-of-fit of an Autoregressive Hilbertian model (ARH(1) model) provides an infinite-dimensional formulation of the approach proposed in Koul and Stute (1999), based on empirical process marked by residuals. Applying a central and functional central limit result for Hilbert-valued martingale difference sequences, the asymptotic behavior of the formulated H-valued empirical process, also indexed by H, is obtained under the null hypothesis. The limiting process is H-valued generalized (i.e., indexed by H) Wiener process, leading to an asymptotically distribution free test. Consistency is also analyzed. The case of misspecified autocorrelation operator of the ARH(1) process is addressed as well. Beyond the Euclidean setting, this approach allows to implement goodness of fit testing in the context of manifold and spherical functional autoregressive processes

    Temperature dependence of the anomalous effective action of fermions in two and four dimensions

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    The temperature dependence of the anomalous sector of the effective action of fermions coupled to external gauge and pseudo-scalar fields is computed at leading order in an expansion in the number of Lorentz indices in two and four dimensions. The calculation preserves chiral symmetry and confirms that a temperature dependence is compatible with axial anomaly saturation. The result checks soft-pions theorems at zero temperature as well as recent results in the literature for the pionic decay amplitude into static photons in the chirally symmetric phase. The case of chiral fermions is also considered.Comment: RevTex, 19 pages, no figures. References adde

    Modelización de la relación altura-diámetro para Pinus pinaster Ait. en Galicia mediante la función de densidad bivariante SBB

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    The bivariate density function SBB has been fitted to height and diameter data of maritime pine (Pinus pinaster Ait.) from 24 sample plots established in even-aged stands of this specie in Galicia (Northwestern Spain). The height-diameter model in maritime pine was estimated using a property of the SBB bivariate distribution. In order to get this, a median regression of SBB function was established between heights and diameters data of each one of the 24 sample plots. The estimated values obtained in the fit has also been used to obtain the curves corresponding to the percentiles of the 5 and 95 % of the height distribution. Finally, a generalized height-diameter function has been developed for Pinus pinaster in Galicia from the equations fitted to each plot, relating the SBB function with the principal stand variables.Se ha ajustado la función de densidad bivariante SBB a datos de altura y diámetro de una muestra de pies de pino marítimo (Pinus pinaster Ait.) pertenecientes a 24 parcelas de ensayo instaladas en masas regulares de dicha especie y repartidas por toda la Comunidad Autónoma de Galicia. Utilizando una propiedad de la distribución bivariante SBB se ha estimado la relación altura-diámetro en pino pinaster. Para ello se realizó un ajuste por regresión de medianas de la función SBB entre los datos de las alturas y los diámetros de los pies de cada una de las 24 parcelas inventariadas. Los estimadores obtenidos en el ajuste también han servido para obtener las curvas correspondientes a los percentiles del 5 y 95%de la distribución de alturas. Posteriormente, y a partir de la ecuación modelizada, se ha construido una función altura-diámetro generalizada, relacionando los parámetros de la función SBB con las principales variables de masa

    Thermal Neutron Relative Biological Effectiveness Factors for Boron Neutron Capture Therapy from In Vitro Irradiations

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    The experimental determination of the relative biological effectiveness of thermal neutron factors is fundamental in Boron Neutron Capture Therapy. The present values have been obtained while using mixed beams that consist of both neutrons and photons of various energies. A common weighting factor has been used for both thermal and fast neutron doses, although such an approach has been questioned. At the nuclear reactor of the Institut Laue-Langevin a pure low-energy neutron beam has been used to determine thermal neutron relative biological effectiveness factors. Different cancer cell lines, which correspond to glioblastoma, melanoma, and head and neck squamous cell carcinoma, and non-tumor cell lines (lung fibroblast and embryonic kidney), have been irradiated while using an experimental arrangement designed to minimize neutron-induced secondary gamma radiation. Additionally, the cells were irradiated with photons at a medical linear accelerator, providing reference data for comparison with that from neutron irradiation. The survival and proliferation were studied after irradiation, yielding the Relative Biological Effectiveness that corresponds to the damage of thermal neutrons for the different tissue types.Asociacion Espanola Contra el Cancer (AECC) PS16163811PORRSpanish MINECO FIS2015-69941-C2-1-PJunta de Andalucia P11-FQM-8229Campus of International Excellence BioTic P-BS-64University of Granada Chair Neutrons for Medicine: the Spanish Fundacion ACSAsociacion Capitan AntonioFundacion ACSLa Kuadrilla de IznallozSonriendo Se Puede Gana

    Radiobiology data of melanoma cells after low-energy neutron irradiation and boron compound administration

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    The cold neutron beam at the PF1b line at the Institut Laue-Langevin (ILL), without fast neutrons and a low contribution of gamma rays, is a very suitable facility to measure cell damage following low-energy neutron irradiation. The biological damage associated with the thermal and the boron doses can be obtained in order to evaluate the relative biological effectiveness (RBE) for Boron Neutron Capture Therapy. Three different experiments were carried out on the A375 melanoma cell line: the first one in a hospital LINAC, to obtain the reference radiation data, and the other two at the ILL, in which the damage to cells with and without boron compounds added was measured

    VERTICAL DISTRIBUTION OF ANCHOVY EARLY STAGES IN THE ALBORAN SEA: VALIDATING TOOLS FOR IBM ECOLOGY IN A REGIONAL CONTEXT

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    Abstract We offer the first data on vertical distribution of anchovy larvae (Engraulis encrasicolus) in the Alboran Sea. Preliminary results show that the vast majority of anchovy larvae distributed in the top 25 m during daytime, suggesting either a lack of vertical migration or a type II migration. Data are discussed in the frame of the potential implications of vertical migration data for spatially -explicit individual-based model escercises being implemented in the are
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