32 research outputs found

    Atmospheric neutrino phenomenology with mass varying neutrinos

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    Orientador: Orlando Luis Goulart PeresTese (doutorado) - Universidade Estadual de Campinas, Instituto de F√≠sica Gleb WataghinResumo: Neste trabalho obtemos de forma independente a descri√ß√£o da distribui√ß√£o angular dos eventos de neutrinos atmosf√©ricos vistos pelo detector Super-Kamiokande tanto para as regi√Ķes de sub-GeV como multi-GeV. Para tal, estudamos de forma detalhada a se√ß√£o de choque neutrinonucleon para processos de espalhamento via corrente carregada para todo o intervalo de energia pelo qual o fluxo de neutrinos atmosf√©ricos se estende. Integramos ent√£o o produto do fluxo de neutrinos atmosf√©ricos pela se√ß√£o de choque de detec√ß√£o dos neutrinos e pela probabilidade de oscila√ß√£o padr√£o de neutrinos atmosf√©ricos e obtemos a distribui√ß√£o angular de eventos em Super-Kamiokande. Atrav√©s de an√°lise de X2 obtivemos uma regi√£o permitida para os par√Ęmetros de oscila√ß√£o padr√£o de neutrinos atmosf√©ricos, a diferen√ßa quadr√°tica de massas, e o √Ęngulo de mistura, sen2(2?23), compat√≠vel com a existente na literatura. Como um teste para oscila√ß√£o n√£o padr√£o introduzimos o modelo de neutrinos com massa vari√°vel(MaVaN¬Ņs), no qual a massa dos neutrinos depende da densidade do meio. Tal efeito √© obtido ao incluir um acoplamento do tipo Yukawa entre os neutrinos e um campo escalar neutro cuja concentra√ß√£o depende da densidade do meio. Estudamos como a inclus√£o deste efeito altera a probabilidade de oscila√ß√£o P¬Ķ?¬Ķ e, consequentemente, a descri√ß√£o dos dados de Super-Kamiokande. Obtemos um limite para o par√Ęmetro aMaV aN respons√°vel pela intensidade deste novo efeito, sendo que solu√ß√Ķes cuja intensidade do efeito de MaVaN √© de 40% ou maior, em compara√ß√£o com a intensidade da oscila√ß√£o padr√ß√£o s√£o exclu√≠das com 90% de n√≠vel de confian√ßaAbstract: In this work we obtain in a independent way the description of the angular distribution of atmospheric neutrino events as seen by the Super-Kamiokande collaboration for the events in the sub-GeV and multi-GeV range. As a first step in this description, we study the neutrino-nucleon charged current cross section for the hole energy range of the experiment, and obtain the number of neutrino events as a function of energy and zenith angle. Including neutrino oscillations in the picture allows us to describe the data from the Super-Kamiokande experiment. We obtain the allowed region for the oscillation parameters ?m223 and sin2(2?23) in reasonable agreement with the result found in the literature. As a test for a non-standard oscillation mechanism we introduce the concept of MaVaN (Mass Varying Neutrinos), derived from the coupling of the neutrinos with a neutral scalar who has its concentration depending of local matter density. The neutrino oscillation probability so changes from the standard oscillation with consequences for the allowed region of oscillation parameters. The parameter amavan describes the relative weight of usual oscillation terms and the MaVaN terms, being aMaV aN = 1 when the two terms are equal. We have found that aMaV aN should be smaller then 0,4 at 90 % C.LDoutoradoF√≠sicaDoutor em Ci√™ncia

    Phenomenology of atmospheric neutrinos

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    Orientador: Orlando Luis Goulart PeresDisserta√ß√£o (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb WataghinResumo: Neste trabalho buscamos entender o fen√īmeno de oscila√ß√Ķes de neutrinos e como exemplo tentamos descrever os dados dos neutrinos atmosf√©ricos Nossa motiva√ß√£o principal √© descrever o excesso de eventos do tipo neutrino eletr√īnico encontrado nos dados do detector SuperKamiokande (SK)a baixas energias quando comparados com o formalismo de oscila√ß√£o de sabores de neutrinos em duas gera√ß√Ķes,o qual resolve o problema da assimetria up-down para os neutrinos atmosf√©ricos do tipo mu√īnico. Para isso generalizamos o modelo de oscila√ß√£o de sabores para tr√™s gera√ß√Ķes de neutrinos, abrindo dessa forma a possibilidade de oscila√ß√£o entre o neutrino eletr√īnico e os demais sabores.Obtemos uma solu√ß√£o semianal√≠tica para o problema nos valendo dos limites impostos pela fenomenologia de neutrinos para os par√Ęmetros de oscila√ß√£o,diferen√ßas quadr√°ticas de massas e √Ęngulos de mistura. Al√©m disso levamos em conta os efeitos de mat√©ria atuando sobre o neutrino eletr√īnico quando este cruza o interior terrestre e tem seu padr√£o de oscila√ß√£o alteradoAbstract: In this work we try to understand the phenomena of neutrino oscillations,and use this to describe more precisely the atmospheric neutrino data.Our main motivation is to describe the excess of events of electron-neutrino type found in the SuperKamiokande results at low energies when compared with the predictions of the two-generation neutrino oscillation which solves the problem of the up-down muon neutrino asymmetry very successfully To do this we generalize the oscillationmodel from two to three neutrino flavors,opening the possibility of oscillation between the electron neutrino type and the others.Then we obtain a semi-analytic solution of the three flavors problem using the neutrino phenomenological limits on oscillation parameters,squared masses differences and mixing angles.We also take into account matter effects on the electronic neutrino when it crosses the Earth and has it ¬Ņs oscillation pattern changedMestradoF√≠sica das Particulas Elementares e CamposMestre em F√≠sic

    Estimating the impact of the QCD dynamics on the determination of the high energy astrophysical neutrino flux

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    The number of ultra-high energy neutrinos arriving at IceCube depends on the energy dependence of the astrophysical neutrino flux and neutrino cross-section. In this paper, we investigate the impact of different assumptions for the description of the QCD dynamics at high energies on the determination of the normalization ő¶Astro\Phi _{Astro} and spectral index ő≥\gamma of the astrophysical neutrino flux. The distribution of neutrino events at the IceCube is estimated considering the DGLAP, BFKL, CGC and BBMT approaches and the best estimates for ő¶Astro\Phi _{Astro} and ő≥\gamma are determined using a maximum likelihood fit comparing the predictions with the distribution of observed events at IceCube. Moreover, we also investigate if the increase in the effective exposure time expected in IceCube-Gen2 will to allow us to disentangle the QCD dynamical effects from the description of the astrophysical neutrino flux

    Implications of the QCD dynamics and a Super-Glashow astrophysical neutrino flux on the description of ultrahigh energy neutrino data

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    The number of events observed in neutrino telescopes depends on the neutrino fluxes in the Earth, their absorption while crossing the Earth and their interaction in the detector. In this paper, we investigate the impact of the QCD dynamics at high energies on the energy dependence of the average inelasticity and angular dependence of the absorption probability during the neutrino propagation through the Earth, as well in the determination of the properties of the incident astrophysical neutrino flux. Moreover, the number of events at the IceCube and IceCube-Gen2 are estimated considering different scenarios for the QCD dynamics and assuming the presence of a hypothetical Super-Glashow flux, which peaks for energies above the Glashow resonance

    The DUNE Far Detector Vertical Drift Technology, Technical Design Report

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    International audienceDUNE is an international experiment dedicated to addressing some of the questions at the forefront of particle physics and astrophysics, including the mystifying preponderance of matter over antimatter in the early universe. The dual-site experiment will employ an intense neutrino beam focused on a near and a far detector as it aims to determine the neutrino mass hierarchy and to make high-precision measurements of the PMNS matrix parameters, including the CP-violating phase. It will also stand ready to observe supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. The DUNE far detector implements liquid argon time-projection chamber (LArTPC) technology, and combines the many tens-of-kiloton fiducial mass necessary for rare event searches with the sub-centimeter spatial resolution required to image those events with high precision. The addition of a photon detection system enhances physics capabilities for all DUNE physics drivers and opens prospects for further physics explorations. Given its size, the far detector will be implemented as a set of modules, with LArTPC designs that differ from one another as newer technologies arise. In the vertical drift LArTPC design, a horizontal cathode bisects the detector, creating two stacked drift volumes in which ionization charges drift towards anodes at either the top or bottom. The anodes are composed of perforated PCB layers with conductive strips, enabling reconstruction in 3D. Light-trap-style photon detection modules are placed both on the cryostat's side walls and on the central cathode where they are optically powered. This Technical Design Report describes in detail the technical implementations of each subsystem of this LArTPC that, together with the other far detector modules and the near detector, will enable DUNE to achieve its physics goals

    The DUNE Far Detector Vertical Drift Technology, Technical Design Report

    No full text
    DUNE is an international experiment dedicated to addressing some of the questions at the forefront of particle physics and astrophysics, including the mystifying preponderance of matter over antimatter in the early universe. The dual-site experiment will employ an intense neutrino beam focused on a near and a far detector as it aims to determine the neutrino mass hierarchy and to make high-precision measurements of the PMNS matrix parameters, including the CP-violating phase. It will also stand ready to observe supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. The DUNE far detector implements liquid argon time-projection chamber (LArTPC) technology, and combines the many tens-of-kiloton fiducial mass necessary for rare event searches with the sub-centimeter spatial resolution required to image those events with high precision. The addition of a photon detection system enhances physics capabilities for all DUNE physics drivers and opens prospects for further physics explorations. Given its size, the far detector will be implemented as a set of modules, with LArTPC designs that differ from one another as newer technologies arise. In the vertical drift LArTPC design, a horizontal cathode bisects the detector, creating two stacked drift volumes in which ionization charges drift towards anodes at either the top or bottom. The anodes are composed of perforated PCB layers with conductive strips, enabling reconstruction in 3D. Light-trap-style photon detection modules are placed both on the cryostat's side walls and on the central cathode where they are optically powered. This Technical Design Report describes in detail the technical implementations of each subsystem of this LArTPC that, together with the other far detector modules and the near detector, will enable DUNE to achieve its physics goals

    The DUNE Far Detector Vertical Drift Technology, Technical Design Report