Orientador: Marcelo Moraes Guzzo / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-09T10:36:51Z (GMT). No. of bitstreams: 1 Oliveira_RobertoLeandroNevesde_M.pdf: 6432345 bytes, checksum: d334d500169812157f60b5fa09ef36ae (MD5) Previous issue date: 2007 / Resumo: Neste trabalho, estudamos algumas conseqüências fenomenológicas da introdução do fenômeno de descoerência quântica na fenomenologia de oscilações de neutrinos. O Modelo de Violação da Mecânica Quântica e o modelo de tratamento de Sistemas Quânticos Abertos são estudados. Mostramos o comportamento e as diferenças entre os dois modelos para encontrar qual deles melhor descreve os sistemas quânticos que podem sofrer efeitos de descoerência. Esses dois modelos são estudados na literatura e ambos incluem efeitos de descoerência na Mecânica Quântica Padrão. Investigamos como o efeito de descoerência pode ser incluído em oscilações de neutrinos e examinamos como a probabilidade padrão pode ser modificada fenomenologicamente quando levamos em conta o efeito de descoerência em duas famílias de neutrinos / Abstract: In this work, we study some phenomenological consequences of the introduction of the quantum decoherence in the phenomenology of neutrinos oscillations. The Model of Violation of the Quantum Mechanics and the general framework of Open Quantum Systems are studied. We explicitly show the behavior and the differences between the two models to find which of them better describes quantum systems that can suffer decoherence effect. These two models are studied in literature and both include decoherence effects in the Quantum Mechanics standard. We investigate how decoherence effects can be included in neutrino oscillations and examine how the standard oscillation probability can be phenomenologically modified when take into account quantum decoherence effects in two neutrinos avor / Mestrado / Física das Particulas Elementares e Campos / Mestre em Física

Orientadores: Carlos Ourivio Escobar, Amir Ordacgi Caldeira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-19T20:52:14Z (GMT). No. of bitstreams: 1 Coelho_JoaodeAbreuBarbosa_D.pdf: 8877509 bytes, checksum: fb8787302605bdb88dd855ddc2b5351f (MD5) Previous issue date: 2012 / Resumo: A oscilação de neutrinos é um modelo muito bem sucedido em explicar uma grande variedade de experimentos. O modelo se embasa na premissa de que os neutrinos que interagem através da força fraca por corrente carregada não são autoestados de massa, mas uma superposição destes. De forma geral, a superposição em sistemas quânticos está sujeita a perda de coerência de forma que estados puros tendem a estados mistos. Esse tipo de evolução não é possível no contexto de sistemas quânticos isolados pois a evolução é unitária e, portanto, invariante por inversão temporal. A quebra da unitariedade permite que uma seta do tempo seja introduzida e o efeito característico para os neutrinos é o amortecimento das oscilações. Investigamos aqui alguns modelos fenomenológicos de descoerência e decaimento que podem ser observados por MINOS, um experimento de oscilação de neutrinos que consiste em medir o uxo de neutrinos produzidos num acelerador de partículas a 735 km de distância. Para esta tese, analisamos o desaparecimento de neutrinos muônicos em MINOS. Informações de outros experimentos são utilizadas para restringir o número de parâmetros de forma que apenas um parâmetro extra é introduzido para cada modelo. Adotamos uma dependência energética em forma de lei de potência para o parâmetro de descoerência. A simulação e software ociais do experimento MINOS são utilizados para obter a sensibilidade do experimento aos efeitos de quebra de unitariedade considerados / Abstract: The neutrino oscillation model is very successful in explaining a large variety of experiments. The model is based on the premise that the neutrinos that interact through the weak force via charged current are not mass eigenstates, but a superposition of them. In general, a quantum superposition is subject to loss of coherence, so that pure states tend toward mixed states. This type of evolution is not possible within the context of isolated quantum systems because the evolution is unitary and, therefore, is invariant under time reversal. By breaking unitarity, an arrow of time is introduced and the characteristic effect for neutrinos is a damping of oscillations. In this thesis, some phenomonological decoherence and decay models are investigated, which could be observed by MINOS, a neutrino oscillation experiment that consists of measuring the neutrino ux produced in a particle accelerator 735 km away. We analyse the disappearance of muon neutrinos in MINOS. Information from other experiments is used to constrain the number of parameters, leaving only one extra parameter in each model. We assume a power law energy dependence of the decoherence parameter. The o-cial MINOS software and simulation are used to obtain the experiment's sensitivities to the eects of unitarity breaking considered / Doutorado / Física / Doutor em Ciências

The IceCube Neutrino Observatory consists of a lattice of 5160 photomultiplier tubes (PMTs)<p>which monitor one cubic kilometer of deep Antarctic ice at the geographic South Pole.<p>IceCube was primarily designed to detect neutrinos of energies greater than O(100 GeV).<p>Due to subfreezing ice temperatures, the photomultipliers' dark noise rates are particularly<p>low which enables IceCube to search for neutrinos from galactic supernovae by detecting<p>bursts of MeV neutrinos emitted during the core collapse and for several seconds following.<p>For that purpose, a dedicated online supernova DAQ system records the total number of hits<p>in the detector, without any further information from the PMTs, and generates supernova<p>candidate triggers in case of a significant detector rate enhancement. A new feature to the<p>standard DAQ, called HitSpooling, was implemented in IceCube during this thesis. The<p>HitSpooling system is implemented in the standard DAQ system and buffers the complete<p>raw data stream of the photomultipliers for several hours or days. By reading out time periods<p>of HitSpool data around supernova candidate triggers, generated by the online supernova<p>DAQ system, we overcome the limitations of the latter and have access to the entire information<p>of the detector in case of a supernova. Furthermore, HitSpool data is a powerful<p>source for studying and understanding the noise behavior of the detector as well as background<p>processes coming from atmospheric muons. The idea of HitSpooling was developed in the<p>scope of this thesis and is the basis of the work at hand. The developed interface between the<p>standard DAQ and the supernova DAQ system is presented. The correlated dark noise component<p>in optical modules of IceCube is quantified for the first time and possible explanations<p>are discussed. The possibility of identifying triggering and subthreshold atmospheric muons<p>in HitSpool data and subtracting them from a possible supernova signal is analyzed. Furthermore,<p>the conversion from HitSpool data to supernova DAQ type data was developed<p>which allows for a comparison of both data types with respect to lightcurves and significances<p>of selected supernova candidate triggers. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

This thesis covers the study of one-loop quantum corrections to the light neutrino masses. In the first part, we examine the extension of the standard model with right-handed neutrinos, where the Seesaw type I is present, allowing accessible masses for experimental searches. However, considering the corrections to the light neutrinos masses requires the pairs of heavy neutrinos to appear as pseudo Dirac particles, implying a suppression of the LNV parameters. In the second part, the supersymmetric contributions are analyzed in order to relax the lepton number violation (LNV) restrictions and achieve a greater difference between the heavy neutrino masses, as well as large mixings. When analyzing the destructive interference between the supersymmetric (which we describe as reducible and irreducible) and non-supersymmetric contributions, we found parameter regions where cancellations occur, however they are very small. So, the addition of SUSY does not guarantee the effect called screening, and the cases that are favorable need some degree of fine-tuning. In all cases, the numerical results of the analytical one-loop expressions calculated in the νRSM and νRMSSM models are checked with SPheno. / Esta tesis cubre el estudio de las correcciones cuánticas a un loop a las masas de neutrinos ligeros. En la primera parte, examinamos la extensión del modelo estándar con neutrinos de mano derecha, donde está presente el Seesaw tipo I, que permite masas accesibles para su búsqueda experimental. Sin embargo, el considerar correcciones a las masas de los neutrinos ligeros requiere que los pares de neutrinos pesados sean considerados como pseudo-Dirac, implicando una supresión de los parámetros LNV. En la segunda parte, se analizan las contribuciones supersimétricas para relajar las restricciones sobre los parámetros de violación de número leptónico (LNV) y lograr una mayor diferencia entre las masas de neutrinos pesados, así como mezclas grandes. Al analizar la interferencia destructiva entre las contribuciones supersimétricas (que describimos como reducibles e irreducibles) y no supersimétricas, encontramos regiones de parametros donde ocurren cancelaciones, pero que son muy pequeñas. Por lo tanto, agregar solo SUSY no garantiza el efecto llamado screening, y los casos que son favorables necesitan cierto grado de ajuste. En todos los casos, los resultados numéricos de las expresiones analíticas a un loop calculadas en los modelos νRSM y νRMSSM se verifican con SPheno.

Una serie de experimentos con neutrinos ha establecido que estos tienen masa, existiendo una mezcla entre sus auto-estados de sabor. La mezcla genera una oscilación entre estos auto-estados durante la propagación de los neutrinos, descrita por una ´ serie de parámetros y por la diferencia cuadrada de las masas. La propuesta con mayor sensibilidad en la medición de los parámetros de oscilación´ radica en futuras instalaciones llamadas fábricas de neutrinos. Estas producirían un alto flujo de neutrinos a partir del decaimiento del muon, siendo capaces de medir una gran variedad de canales de oscilación. ´ No obstante, la medición de los parámetros se ve afectada por la existencia de degeneraciones en la probabilidad de oscilación, las cuales permiten la aparición de resultados ambiguos en el momento de determinar los parámetros reales. En este trabajo se analiza el problema de las degeneraciones y se recomienda la realización de mediciones en los canales νe → νµ, νe → ντ y νµ → νµ, junto con sus respectivas antipartículas, con el fin de resolver cualquier ambigüedad. Las fábricas de neutrinos son simuladas incluyendo errores debidos a la divergencia del ´ haz, a la resolución energética y a la eficiencia en la detección. La medición de los tres canales de oscilación se realiza a 3000 km de la fuente de neutrinos. Aquellos casos con un pequeño número de eventos presentan tres tipos de degeneraciones, estando una de éstas presente incluso en casos particulares con un mayor número de eventos. Se estudia, en particular, la dependencia de la resolución de todas las degeneraciones con respecto a la eficiencia y masa del detector del canal νe → ντ , así como los efectos de combinar estos datos con aquellos para una distancia de 7250 km. Los resultados se presentan a través del uso de regiones de confiabilidad definidas en el análisis estadístico. A partir de ellas se establecen los límites posibles en la resolución del problema, considerando varios parámetros de oscilación.

The purpose of this thesis was to design, build, and test a device capable of simulating the acoustic pulse expected from the interaction between an Ultra-High Energy (UHE) neutrino and seawater. When a neutrino interacts with seawater, the reaction creates a long, narrow shower of sub-atomic particles. The energy from this reaction causes nearly instantaneous heating of the seawater on an acoustic timescale. The acoustic pulse created by the resulting thermal expansion of the water is predicted to be bipolar in shape. This work was undertaken to support a Stanford experiment, the Study of Acoustic Ultra-high energy Neutrino Detection (SAUND), that uses existing hydrophone arrays to detect UHE neutrinos from the acoustic pulse generated by their rare interactions with seawater. The device fabricated for this thesis uses the discharge current from a 4 microFarads capacitor charged to 2.5kV to heat the seawater between two copper plates. The anode and cathode plates of this "zapper" design were 6 cm in diameter and 20 cm apart. The acoustic pulse generated by the zapper was measured both in a small test tank at NPS and at the Acoustic Test Facility located at NUWC Keyport. Bipolar pulses observed at NPS on two separate test dates had average pulse lengths of 110 microseconds +/- 10 microseconds and 160 +/- 20 microseconds and average amplitudes at 1m of 1.9 +/- 0.3Pa and 4.7 +/- 0.6Pa. The average pulse length recorded at Keyport was 49 +/- 6 microseconds and the average amplitude at 1m was 6.4 +/- 0.9Pa. The pulse lengths recorded at NPS were reasonably consistent with theory, however all pressure amplitudes were about 100 times lower than predicted. The cause of the amplitude discrepancy is not completely understood at this time.

The XX century witnessed the quantum and relativistic revolutions in physics. The development of these two theories, namely, Quantum Mechanics and Relativity, was the inception of many crucial discoveries and technological advances. Among them, one stands out due to its uniqueness, the neutrino discovery. However, several neutrino properties are still obscure. Neutrinos are the only fundamental particles whose nature is currently unknown. Such fermions can either be different from their antiparticles, i.e., Dirac fermions, or be their own antiparticles, that is, Majorana fermions. On the other hand, the smallness of neutrino masses is a problem seemingly related to the neutrino nature; thus, as essential task consists in addressing the phenomenologically viable models in both cases. Furthermore, it is important to search for other physical process in which the neutrino nature may manifest through different experimental signatures. A rather difficult but promising method corresponds to the detection of the cosmic neutrino background, viz. neutrinos which are relics from the Big Bang. Previous works have shown that detection rates for Dirac and Majorana neutrinos can give different results. Nevertheless, this distinction was obtained considering the Standard Model framework only. Therefore, it is important to understand the consequences of having Non-Standard Interactions contributing to the detection of neutrinos from the cosmic background. Another remarkable relic predicted by Cosmology is the unidentified Dark Matter, composing ~25% of the Universe. All searches regarding the Weakly Interacting Massive Particle, one of the principal candidates for Dark Matter, have given negative results; this has compelled experiments to increase their sensitivity. Notwithstanding, neutrinos may stand in the way of such experimental searches given that they may constitute an irreducible background. In this thesis, we will address these three different phenomena, neutrino mass models, detection of the cosmic neutrino background and the neutrino background in Dark Matter searches, by considering the different characteristics in each case. In the study of neutrino mass models, we will consider models for both Majorana and Dirac neutrinos; specifically, we will probe the neutrinophilic two-Higgs-doublet model. Regarding the detection of relic neutrinos, we will analyse the consequences of the existence of the beyond Standard Model physics in the capture rate by tritium. Finally, we will scrutinize the impact of neutrinos in Direct Detection WIMP searches, by considering Standard Model plus additional interactions in the form of simplified models. / Ao longo do século XX testemunhamos as revoluções quântica e relativista que aconteceram na Física. O desenvolvimento da Mecânica quântica e da teoria da relatividade foi o prelúdio de inúmeras descobertas e avanços tecnológicos fundamentais; em particular, a descoberta dos neutrinos. No entanto, a sua total compreensão ainda é um mistério para a física de partículas. Entendidos como partículas fermiônicas fundamentais, os neutrinos possuem sua natureza desconhecida. Podendo ser diferentes de suas antipartículas, denominadas férmions de Dirac, ou também podendo ser as suas próprias antipartícula, sendo conhecidas como férmions de Majorana. Por outro lado, o valor de sua massa continua sendo um problema em aberto, supostamente relacionado à sua natureza. Portanto, é importante estudarmos modelos fenomenológicos viáveis para as duas naturezas possíves dos neutrinos. Além disso, é necessário procurar outros processos físicos cujos resultados experimentais sejam distintos de acordo com a natureza do neutrino. Um método bastante difícil, mas promissor, corresponde à detecção do fundo de neutrinos cósmicos, isto é, os neutrinos relíquia do Big Bang. Análises prévias mostraram que as taxas de detecção para neutrinos de Dirac e de Majorana resultam em valores distintos. Porém, este resultado foi obtido supondo como base o Modelo Padrão; assim, é crucial entender as possíveis consequências da existência de interações desconhecidas na detecção dos neutrinos da radiação cósmica de fundo. Outra relíquia notável prevista pela Cosmologia é a desconhecida Matéria Escura, que compõe ~25% do Universo. Todas as buscas por WIMPs (do inglês Weakly Interactive Massive Particles), um dos principais candidatos a Matéria Escura, tem dado resultados negativos. Isto tem forçado a criação de experimentos cada vez mais sensíveis. Contudo, os neutrinos poderão ser um obstáculo nessas buscas experimentais, pois estes convertir-se-ão em um fundo irredutível. Na presente tese, abordaremos estes três fenômenos diferentes, modelos de massa para os neutrinos, a detecção do fundo de neutrinos cósmicos e o fundo de neutrinos em experimentos de detecção direta de Matéria Escura, considerando as distintas características em cada caso. No estudo dos modelos de massa para os neutrinos consideraremos modelos para neutrinos de Majorana e Dirac; exploraremos modelos neutrinofílicos com dois dubletos de Higgs. Enquanto à detecção dos neutrinos relíquia, analisaremos as consequências da presença de física além do Modelo Padrão na taxa de captura pelo trítio. Finalmente, examinaremos o impacto dos neutrinos em experimentos de detecção direta de WIMPs, supondo as interações do Modelo Padrão junto com interações adicionais na forma de modelos simplificados.

We apply the Jansson-Farrar JF12 magnetic field model in the context of point source searches by correlating the Telescope Array ultrahigh energy cosmic ray data and the IceCube-40 neutrino candidates, as well as other magnetic field hypotheses. Our field hypotheses are: no magnetic field, the JF12 field considering only the regular component, the JF12 full magnetic field, which is a combination of regular and random field components, and the standard turbulent magnetic field used in previous correlation analyses. As expected from a neutrino sample such as IceCube-40, consistent with atmospheric neutrinos, we have found no significant correlation signal in all the cases. Therefore, this paper is mainly devoted to the comparison of the effect of the different magnetic field hypotheses on the minimum neutrino source flux strength required for a 5σ discovery and the derived 90% C.L. upper limits. We also incorporate in our comparison the cases of different power law indices α= 2.2, α=2.5 for the neutrino point source flux. The differences in the 5σ discovery flux for our magnetic field hypotheses is ∼1%–50%, being the maximum difference with the regular JF12 field and standard turbulent field models, being the standard turbulent higher than the regular one, while the minimum is between the no magnetic field and regular JF12 field. Considering the current flux upper limits, we find that IceCube requires a lifetime ≳5 years to observe neutrino-UHECR correlation signals. Our analysis for different power law indices yielded the same relative behavior between different magnetic field models. / Tesis

The discovery of the Higgs boson in the 8 TeV run of the LHC [1, 2] marks one of the most important milestones in particle physics. Its mass is already known rather precisely: mh = 125.09 ± 0.21 (stat.) ±0.11 (syst.) GeV [3], and the signal strength of various LHC searches has been found consistent with the SM predictions. While this completes the Standard Model (SM) particle-wise, several questions still remain open, for example: (i) Is it possible to include the SM in a grand unified theory where all gauge forces unify? (ii) Is there a particle physics explanation of the observed dark matter relic density? (iii) What causes the hierarchy in the fermion mass spectrum and why are neutrinos so much lighter than the other fermions? What causes the observed mixing patterns in the fermion sector? (iv) What stabilizes the Higgs mass at the electroweak scale? Supersymmetric model address several of these questions and consequently the search for supersymmetry (SUSY) is among the main priorities of the LHC collaborations. Up to now no significant sign for physics beyond SM has been found. The combination of the Higgs discovery with the (yet) unsuccessful searches has led to the introduction of a model class called ‘natural SUSY’ [4–15]. Here, the basic idea is to give electroweak-scale masses only to those SUSY particles giving a sizeable contribution to the mass of the Higgs boson, such that a too large tuning of parameters is avoided. All other particle masses are taken at the multi-TeV scale. In particular, masses of the order of a few hundred GeV up to about one TeV are assigned to the higgsinos (the partners of the Higgs bosons), the lightest stop (the partner of the top-quark) and, if the latter is mainly a left-stop, also to the light sbottom In addition the gluino and the heavier stop masses should also be close to at most a few TeV. Neutrino oscillation experiments confirm that at least two neutrinos have a non-zero mass. The exact mass generation mechanism for these particles is unknown, and both the SM and the MSSM remain agnostic on this topic. Although many ways to generate neutrino mass exist, perhaps the most popular one is the seesaw mechanism [16–21]. The main problem with the usual seesaw mechanisms lies on the difficulty in testing its validity. In general, if Yukawa couplings are sizeable, the seesaw relations require Majorana neutrino masses to be very large, such that the new heavy states cannot be produced at colliders. In contrast, if one requires the masses to be light, then the Yukawas need to be small, making production cross-sections and decay rates to vanish. A possible way out of this dilemma lies on what 3 is called the inverse seesaw [22], which is based on having specific structures on the mass matrix (generally motivated by symmetry arguments) to generate small neutrino masses. This, at the same time, allows Yukawa couplings to be large, and sterile masses to be light. We consider here a supersymmetric model where neutrino data are explained via a minimal inverse seesaw scenario where the gauge-singlet neutrinos have masses in the range O(keV) to O(100 GeV). We explore this with a parametrization built for the standard seesaw, and go to the limit where the inverse seesaw emerges, such that Yukawas and mixings become sizeable. Although non-SUSY versions of this scenario can solve the dark matter and matter-antimatter asymmetry problems [23–25], we shall make no claim on these issues in our model. In view of the naturalness arguments, we further assume that the higgsinos have masses of O(100 GeV), whereas the gaugino masses lie at the multi-TeV scale (see [26] for an example of such a scenario). In addition, we assume all squarks are heavy enough such that LHC bounds are avoided, and play no role in the phenomenology within this work1. In contrast we allow for fairly light sleptons and investigate the extent to which current LHC data can constrain such scenarios. This paper is organized as follows: in the next section we present the model. Section III summarizes the numerical tools used and gives an overview of the LHC analysis used for these investigations. In Section IV we present our findings for the two generic scenarios which differ in the nature of the lighest supersymmetric particle (LSP): a Higgsino LSP and a sneutrino LSP. In Section V we draw our conclusions. Appendices A and B give the complete formulae for the neutrino and sneutrino masses. / Tesis

In this thesis, a number of aspects of neutrino oscillation physics are investigated, focusing on the design and phenomenology of next generation neutrino beam experiments. In working to optimise the sensitivity of the Hyper-Kamiokande experiment, new reconstruction software has been developed to meet the goal of fast, flexible reconstruction of particle positions, directions, energies and species. This is demonstrated for the TITUS intermediate detector, producing samples of neutrino interactions to constrain systematic uncertainties of oscillation analyses. Inclusion of these samples achieves a reduction of over 50% of systematic errors in measurements of 23 and and increases the parameter space for CP violation discovery after 10 years at 5 from 51% to 74%. A full analysis is presented of a potential neutron measurement at the E61 detector, including full simulations of all major backgrounds, a likelihood method of background removal, and a procedure for correcting for efficiency and backgrounds. Large, pure samples are produced, with the ability to accurately reproduce true distributions of neutron capture multiplicity, distance and angle relative to neutrino interactions, with true and reconstructed distributions agreeing within 2%. The sensitivities of Hyper-Kamiokande, including with a possible second tank in Korea, in combination with the DUNE experiment, have been thoroughly investigated. Several areas of strong synergy are identified, with the optimal combination of experiments possessing the ability to definitively resolve all remaining unknowns of 3-neutrino oscillations: determining both the octant of 23 and the mass-ordering in under 2 years and discovering CP violation at 5 for 50% of parameter space after 5 years. The highly predictive Littlest Seesaw flavour models of neutrino masses and mixing are tested against current oscillation data, finding no tension even at 1 . The ability of the next-generation experiments' oscillation measurements to probe these models is investigated, with all strands of the programme, including long baseline beam experiments and short and medium baseline reactor experiments, found to show high potential to exclude the models both individually and in combination.