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Orientador: Orlando Luís Goulart Peres Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin Resumo: Nesta tese discutimos vários aspectos da física de neutrinos. Começamos introduzindo o estado atual descrevendo a teoria padrão de oscillação de neutrinos. Exploramos também vários cenários de física exótica, aquela além da teoria padrão de oscilações que possam ser testadas em experiments atuais e futuros. Dividimos o trabalho em duas frentes: Fenomenologia e Teoria. Na parte de fenomenologia trabalhamos com interações não-padrão de neutrinos, não-unitariedade da matriz de mistura e efeitos de curta distancia em experimentos de oscilação. Na parte teórica nós analisamos modelos específicos como o Warped Flavor Symmetry Model e o Revamped A4 , nos quais utilizamos de correlações entre o ângulo de mistura atmosférico e a fase de CP para obter limites no espaço de parâmetro dos modelos Além disso, mostramos que é possível utilizar uma relação simples entre o ângulo atmosférico e o ângulo de reatores para, de forma independente de modelo, restringir modelos de massa de neutrinos de alta energia Abstract: In this Thesis, we discuss several aspects of flavor neutrino physics. From the standard picture of neutrino physics, we describe the present scenario of neutrino oscillations and explore many beyond standard oscillation scenarios that could be observed or tested in current and future experiments. In the phenomenological side, we worked with Non-standard neutrino interactions and Non-unitarity of the neutrino mixing matrix in long and short baseline experiments. In the theoretical side, we also analyzed specific models such as the Warped Flavor Symmetry and the Revamped A4, where we used the correlations among the atmospheric mixing angle and the CP-phase. We showed that it is possible to use also the correlation between the atmospheric and the reactor angle to model-independently constraint high energy neutrino mass models Doutorado Física Doutor em Ciências FAPESP 2014/05133-1, 2015/16809-9 CAPES 1504581/2015

Agradecimentos: We thank Adam Aurisano and Jeremy Hewes for very instructive discussions and for information regarding the capabilities of the DUNE experimental setup. The work of A. dG. and K. J. K. was supported in part by DOE Grant No. de-sc0010143. The work of G. V. S. was supported by FAPESP funding Grants No. 2016/00272-9 and No. 2017/12904-2 and P. P. thanks the support of FAPESP-CAPES funding Grants No. 2014/05133-1, 2014/19164-6, and No. 2015/16809-9 Also the partial support from FAEPEX funding Grant, No. 2391/17 and the Fermilab NPC grant. G. V. S. and P. S. P. also thank the partial support of the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior-Brasil (CAPES)-Finance Code 001. This manuscript has been authored in part by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics Abstract: We explore the capabilities of the upcoming Deep Underground Neutrino Experiment (DUNE) to measure nu(tau) charged-current interactions and the associated oscillation probability P(nu(mu) -gt; nu(tau)) at thorn at its far detector, concentrating on how such results can be used to probe neutrino properties and interactions. DUNE has the potential to identify significantly more nu(tau) events than all existing experiments and can use this data sample to nontrivially test the three-massive-neutrinos paradigm by providing complementary measurements to those from nu(e)-appearance nu(mu)-disappearance channels. We further discuss the sensitivity of the nu(tau)-appearance channel to several hypotheses for the physics that may lurk beyond the three-massive-neutrinos paradigm: a nonunitary lepton mixing matrix, the 3 + 1 light neutrinos hypothesis, and the existence of nonstandard neutral-current neutrino interactions. Throughout, we also consider the relative benefits of the proposed high-energy tune of the Long-Baseline Neutrino Facility (LBNF) beam line COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Aberto

The mixing of three active neutrino flavors is parameterized by the unitary PMNS matrix. If there are more than three neutrino flavors and if the extra generations are heavy isosinglets, the effective $3\times 3$ mixing matrix for the three active neutrinos will be non-unitary. We have analyzed the latest T2K and \nova data with the hypothesis of non-unitary mixing of the active neutrinos. We found that the 2019 NO$��$A data slightly (at $\sim 1\, ��$ C.L.) prefer the non-unitary mixing over unitary mixing. In fact, allowing the non-unitary mixing brings the \nova best-fit point in the $\sin^2��_{23}-��_{CP}$ plane closer to the T2K best-fit point. The 2019 T2K data, on the other hand, cannot rule out any of the two mixing schemes. A combined analysis of the NO$��$A and T2K 2019 data prefers the non-unitary mixing at $1\, ��$ C.L.. We derive constraints on the non-unitary mixing parameters using the best-fit to the combined NO$��$A and T2K data. These constraints are weaker than previously found. The latest 2020 data from both the experiments prefer non-unitarity over unitary mixing at $1\, ��$ C.L. The combined analysis preferes non-unitarity at $2\, ��$ C.L. The stronger tension, which exists between the latest 2020 data of the two experiments, also gets reduced with non-unitary analysis., 30 pages, 19 figures, 3 tables. Results for 2020 data from NOvA and T2K have been included, Accepted in EPJC

Agradecimentos: Pedro Pasquini was supported by FAPESP Grants 2014/05133-1, 2015/16809-9, and 2014/19164-6 and FAEPEX Grant no. 2391/17 and, also, by the APS-SBF collaboration scholarship Abstract: We review the current status of neutrino oscillation experiments, mainly focusing on T2(H) K, NO upsilon A, and DUNE. Their capability to probe high energy physics is found in the precision measurement of the CP phase and theta(23). In general, neutrino mass models predict correlations among the mixing angles that can be used to scan and shrink their parameter space. We updated previous analysis and presented a list of models that contain such structure FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Aberto

Agradecimentos: The authors would like to thank G. V. Stenico for providing the SBND GloBEbS code for the detectors. This work was supported by the Spanish Grants FPA2017-85216-P and SEV-2014-0398 (MINECO), PROMETEOII/2014/084, and GV2016-142 Grants from Generalitat Valenciana. M. T. is also supported by a Ramon y Cajal contract (MINECO). O. G. M. was supported by CONACyT and SNI (Mexico). P. P. thanks FAPESP-CAPES for the support of the funding Grants No. 2014/05133-1, No. 2014/19164-6, and No. 2015/16809-9, and the partial support from the FAEPEX Funding Grant No. 2391/17 Abstract: We study the capabilities of the short-baseline neutrino program at Fermilab to probe the unitarity of the lepton mixing matrix. We find the sensitivity to be slightly better than the current one. Motivated by the future DUNE experiment, we have also analyzed the potential of an extra liquid Argon near detector in the LBNF beamline. Adding such a near detector to the DUNE setup will substantially improve the current sensitivity on nonunitarity. This would help to remove CP degeneracies due to the new complex phase present in the neutrino mixing matrix. We also study the sensitivity of our proposed setup to light sterile neutrinos for various configurations FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Aberto

Agradecimentos: P. P. was supported by FAPESP-CAPES Grants No. 2014/05133-1, No. 2015/16809-9, and No. 2014/19164-6, and FAEPEX Grant No. 2391/17 Abstract: We perform a simulation on the DUNE experiment to probe the capability of future neutrino longbaseline experiments to constrain the parameter space of high-energy models by using the correlation between the atmospheric and reactor mixing angles. As an example, we analyze the tetrahedral flavor symmetry model, which predicts a strong relation between the nonzero value of theta(13) and a deviation of theta(23) from maximality. We show that in this case, the model can realistically be excluded by more than 3 sigma for most of the parameter space. We also study the octant degeneracy at DUNE and its impact on the sensitivity of such models FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Aberto

Agradecimentos: This research is supported by the Spanish grants FPA2014- 58183-P, Multidark CSD2009-00064, SEV-2014-0398 (MINECO) and PROMETEOII/2014/084 (Generalitat Valenciana). P. S. P. acknowledges the support of FAPESP grant 2014/05133-1, 2015/16809-9 and 2014/19164-6 Abstract: We perform realistic simulations of the current and future long baseline experiments such as T2K, NOvA, DUNE and T2HK in order to determine their ultimate potential in probing neutrino oscillation parameters. We quantify the potential of these experiments to underpin the octant of the atmospheric angle 023 as well as the value and sign of the CP phase delta(CP) We do this both in general, as well as within the predictive framework of a previously proposed [1] benchmark theory of neutrino oscillations which tightly correlates theta(23) and delta(CP) FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Aberto

Agradecimentos: Work supported by the Spanish Grants No. FPA2014-58183-P and No. SEV-2014-0398 (MINECO), and PROMETEOII/2014/084 (Generalitat Valenciana). P. S. P. acknowledges the support of FAPESP/CAPES Grants No. 2014/05133-1, No. 2015/16809-9 and No. 2014/19164-6 Abstract: Taking into account the current global information on neutrino oscillation parameters we forecast the capabilities of future long-baseline experiments such as DUNE and T2HK in settling the atmospheric octant puzzle. We find that a good measurement of the reactor angle theta(13) plays a key role in fixing the octant of the atmospheric angle theta(23) with such future accelerator neutrino studies FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Aberto

Agradecimentos: Work supported by Spanish Grants No. FPA2014-58183-P, Multidark CSD2009-00064, SEV-2014-0398 (MINECO) and PROMETEOII/2014/084 (Generalitat Valenciana). P. P. acknowledges the support of FAPESP/CAPES Grants No. 2014/05133-1, No. 2015/16809-9 and No. 2014/19164-6 Abstract: Here we study the pattern of neutrino oscillations emerging from a previously proposed warped standard model construction incorporating Delta(27) flavor symmetry [J. High Energy Phys. 01 (2016) 007]. In addition to a complete description of fermion masses, the model predicts the lepton mixing matrix in terms of two parameters. The good measurement of. theta(13) makes these two parameters tightly correlated, leading to an approximate one-parameter description of neutrino oscillations. We find secondary minima for the CP phase absent in the general unconstrained oscillation scenario and determine the fourfold degenerate sharp correlation between the physical CP phase delta(CP) and the atmospheric mixing angle. theta(23). This implies that maximal. theta(23) correlates with maximal leptonic CP violation. We perform a realistic estimate of the total neutrino and antineutrino event numbers expected at long baseline oscillation experiments T2K, NOvA, and the upcoming DUNE proposal. We show how an improved knowledge of the CP phase will probe the model in a significant way FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES Aberto

Agradecimentos: Work supported by Spanish Grants No. FPA2014-58183-P, No. Multidark CSD2009-00064, No. SEV-2014-0398 (MINECO), No. PROMETEOII/2014/084 (Generalitat Valenciana). M. T. is also supported by the Grant No. GV2016-142 (Ayuda para Proyectos Emergentes, Generalitat Valenciana) and by a Ramon y Cajal contract (MINECO). P. S. P. would like to thank the support of FAPESP funding Grants No. 2014/05133-1, No. 2015/16809-9, and No. 2014/19164-6. S. F. G. thanks Jarah Evslin for useful discussions Abstract: Non-unitary neutrino mixing implies an extra CP violating phase that can fake the leptonic Dirac CP phase delta(CP) of the simplest three-neutrino mixing benchmark scheme. This would hinder the possibility of probing for CP violation in accelerator-type experiments. We take T2K and T2HK as examples to demonstrate the degeneracy between the "standard" (or "unitary") and "nonunitary" CP phases. We find, under the assumption of nonunitary mixing, that their CP sensitivities severely deteriorate. Fortunately, the TNT2K proposal of supplementing T2(H)K with a mu DAR source for better measurement of delta(CP) can partially break the CP degeneracy by probing both cos delta(CP) and sin delta(CP) dependences in the wide spectrum of the mu DAR flux. We also show that the further addition of a near detector to the mu DAR setup can eliminate the degeneracy completely FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Aberto

Agradecimentos: Work supported by Spanish grants FPA2014-58183-P, SEV-2014-0398 (MINECO) and PROMETEOII/2014/084 (Generalitat Valenciana). P. P. was supported by FAPESP grants 2014/05133-1, 2015/16809-9, 2014/19164-6 and FAEPEX grant N. 2391/17 Abstract: Using the latest global determination of neutrino oscillation parameters from [1] we examine the status of the simplest revamped version of the BMV (Babu-Ma-Valle) model, proposed in [2]. The model predicts a striking correlation between the "poorly determined" atmospheric angle 623 and CP phase Sep, leading to either maximal CP violation or none, depending on the preferred 623 octants. We determine the allowed BMV parameter regions and compare with the general three-neutrino oscillation scenario. We show that in the BMV model the higher octant is possible only at 99% C. L., a stronger rejection than found in the general case. By performing quantitative simulations of forthcoming DUNE and T2HK experiments, using only the four "well-measured" oscillation parameters and the indication for normal mass ordering, we also map out the potential of these experiments to corner the model. The resulting global sensitivities are given in a robust form, that holds irrespective of the true values of the oscillation parameters FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Aberto