264 research outputs found

    Possible scenario for MaVaN's as the only neutrino flavor conversion mechanism in the Sun

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    Mass Varying neutrino mechanisms were proposed to link the neutrino mass scale with dark energy, addressing the coincidence problem. In some scenarios this mass can present a dependence on the baryonic density felt by neutrinos, creating an effective neutrino mass that depends both on the neutrino and baryonic densities. In this article we investigate the possibility that a neutrino effective mass is the only flavour conversion mechanism acting in neutrino oscillation experiments. We present a parameterization on the environmental effects on neutrino mass that produces the right flavour conversion probabilities for solar and terrestrial neutrinos experiments.Comment: 12 pages, 4 figure

    Quantum Dissipation in a Neutrino System Propagating in Vacuum and in Matter

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    Considering the neutrino state like an open quantum system, we analyze its propagation in vacuum or in matter. After defining what can be called decoherence and relaxation effects, we show that in general the probabilities in vacuum and in constant matter can be written in a similar way, which is not an obvious result in this approach. From this result, we analyze the situation where neutrinos evolution satisfies the adiabatic limit and use this formalim to study solar neutrinos. We show that the decoherence effect may not be bounded by the solar neutrino data and review some results in the literature. We discuss the current results where solar neutrinos were used to put bounds on decoherence effects through a model-dependent approach. We conclude explaining how and why this models are not general and we reinterpret these constraints.Comment: new version: title was changend and was added a table. To appear at Nucl. Physic.

    On the Effects of Quantum Decoherence in a Future Supernova Neutrino Detection

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    Quantum decoherence effects in neutrinos, described by the open quantum systems formalism, serve as a gateway to explore potential new physics, including quantum gravity. Previous research extensively investigated these effects across various neutrino sources, imposing stringent constraints on the spontaneous loss of coherence. In this study, we demonstrate that even within the Supernovae environment, where neutrinos are released as incoherent states, quantum decoherence could influence the flavor equipartition of 3ν3\nu mixing. Additionally, we examine the potential energy dependence of quantum decoherence parameters (Γ=Γ0(E/E0)n\Gamma = \Gamma_0 (E/E_0)^n) with different power laws (n=0,2,5/2n = 0, 2, 5/2). Our findings indicate that future-generation detectors (DUNE, Hyper-K, and JUNO) can significantly constrain quantum decoherence effects under different scenarios. For a Supernova located 10 kpc away from Earth, DUNE could potentially establish 3σ3\sigma bounds of Γ≤6.2×10−14\Gamma \leq 6.2 \times 10^{-14} eV in the normal mass hierarchy (NH) scenario, while Hyper-K could impose a 2σ2\sigma limit of Γ≤3.6×10−14\Gamma \leq 3.6 \times 10^{-14} eV for the inverted mass hierarchy (IH) scenario with n=0n=0 - assuming no energy exchange between the neutrino subsystem and non-standard environment ([H,Vp]=0[H,V_p] = 0). These limits become even more restrictive for a closer Supernova. When we relax the assumption of energy exchange ([H,Vp]≠0[H,V_p] \neq 0), for a 10 kpc SN, DUNE can establish a 3σ3\sigma limit of Γ8≤4.2×10−28\Gamma_8 \leq 4.2 \times 10^{-28} eV for NH, while Hyper-K could constrain Γ8≤1.3×10−27\Gamma_8 \leq 1.3 \times 10^{-27} eV for IH (n=0n=0) with 2σ2\sigma, representing the most stringent bounds reported to date. Furthermore, we examine the impact of neutrino loss during propagation for future Supernova detection

    SN1987A neutrino burst: limits on flavor conversion

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    In this paper, we revisit the SN1987A neutrino data to see its constraints on flavor conversion. We are motivated by the fact that most works that analyze this data consider a specific conversion mechanism, such as the MSW (Mikheyev-Smirnov-Wolfenstein) effect, although flavor conversion is still an open question in supernovae due to the presence of neutrino-neutrino interactions. In our analysis, instead of considering a specific conversion mechanism, we let the electron antineutrino survival probability Pe‾e‾P_{\overline{e}\overline{e}} be a free parameter. We fit the data from Kamiokande-II, Baksan, and IMB detected spectrum with two classes of models: time-integrated and time-dependent. For the time-integrated model, it is not possible to put limits above 1σ1\sigma (68% confidence level) on the survival probability. The same happens for the time-dependent model when cooling is the only mechanism of antineutrino emission. However, for models considering an accretion phase, Pe‾e‾∼0P_{\overline{e}\overline{e}}\sim0 is strongly rejected, showing a preference for the existence of an accretion component in the detected antineutrino flux, and a preference for normal mass ordering when only the MSW is present.Comment: 13 pages,10 figures. Version Accepted for publication. Some updates were made in the analysis with no significant deviations from previous result

    Interação de neutrinos com campos magnéticos rotantes

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    Orientador: Marcelo Moraes GuzzoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica "Gleb Wataghin"Resumo: Investigamos a possibilidade de melhorar os limites experimentais do momento magnético do neutrino através de experimentos controlados de conversão de quiralidade. Como neutrinos de quiralidade "right" não interagem com a matéria, a detecção de uma supressão em relação ao fluxo inicial de neutrinos poderia nos dar um valor para o seu momento magnético, ou caso tal supressão não fosse detectada, novos limites experimentais poderiam ser estabelecidos. Ressonâncias na conversão de quiralidade podem ser obtidas através da interação diferenciada de neutrinos com campos magnéticos rotantes. Dado um valor para o momento magnético do neutrino e uma parametrização das grandezas físicas envolvidas no problema, tais como o valor do campo magnético e sua variação angular, estudamos em que situações estas ressonâncias podem produzir uma situação otimal para a realização de experimentos deste tipoAbstract: We investigate the possibility of obtaining neutrino magnetic moment experimental limits through controled experiments of chirality conversion. Because right-handed neutrinos do not interact with matter, a suppression detection related to the initial neutrino flux could give us a value to its magnetic moment, or in the absence of such suppression, new experimental limits could be established. Resonances in the chirality conversion can be obtained through the neutrino interaction with rotating magnetic fields. Given a value of the neutrino magnetic moment and a parametrization choice of the relevant physical quantities, like the magnetic field magnitude and its angular velocity, we study in which situations these resonances could produce the best situation to the realization of this kind of experimentsMestradoFísicaMestre em Físic

    Cracking KD-Tree: The first multidimensional adaptive indexing

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    Workload-aware physical data access structures are crucial to achieve short response time with (exploratory) data analysis tasks as commonly required for Big Data and Data Science applications. Recently proposed techniques such as automatic index advisers (for a priori known static workloads) and query-driven adaptive incremental indexing (for a priori unknown dynamic workloads) form the state-of-the-art to build single-dimensional indexes for single-attribute query predicates. However, similar techniques for more demanding multi-attribute query predicates, which are vital for any data analysis task, have not been proposed, yet. In this paper, we present our on-going work on a new set of workload-adaptive indexing techniques that focus on creating multidimensional indexes. We present our proof-of-concept, the Cracking KD-Tree, an adaptive indexing approach that generates a KD-Tree based on multidimensional range query predicates. It works by incrementally creating partial multidimensional indexes as a by-product of query processing. The indexes are produced only on those parts of the data that are accessed, and their creation cost is effectively distributed across a stream of queries. Experimental results show that the Cracking KD-Tree is three times faster than creating a full KD-Tree, one order of magnitude faster than executing full scans and two orders of magnitude faster than using uni-dimensional full or adaptive indexes on multiple columns
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