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The discovery of neutrino oscillations established the fact that they are massive particles. This is a clear signal of physics beyond the Standard Model, since this theoretical framework cannot explain how the neutrino mass terms can be generated. Furthermore, because this phenomenon is strictly a quantum one it can be used to study even more the quantum realm. In this work we shall take advantage of the sensitivity of this phenomenon to new effects. Since the neutrino physics has entered a precision measurement era, we expect that such modifications can be further constrained, or even confirmed, with new experimental results. We will focus on a very special kind of effects, the Open Quantum System effects. This is an interesting theoretical framework because it is a predictive description which can also handle our lack of information about the neutrino system. For that purpose we will study the theoretical basis of neutrino oscillations and Open Quantum System effects, discuss how to include both in the time evolution of the neutrino system and investigate how the new effects can change the oscillation pattern. Finally, we will use the public data released by the IceCube experiment to analyze the consequences and also constrain such modifications.

In the usual quantum field theoretical approach, neutrino oscillations are studied diagonalizing either the mass or matter Hamiltonians. In this paper we analyze the problem from an on-shell amplitude perspective, where Lagrangians or Hamiltonians are not available. We start by studying in detail how flavor enters in the amplitudes and how the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix emerges. We then analyze the elastic amplitude of two neutrinos and two charged leptons that induce matter effects and propose a strategy to obtain the known results of the standard oscillation theory without Hamiltonians. Finally, we extend the previously proposed procedure and use the most general elastic 4-point amplitude to study beyond the Standard Model effects on oscillations.

We explore the neutrino sector of the minimal left-right symmetric model, with the additional charge conjugation discrete symmetry, in the tuned regime where type-I and type-II seesaw mechanisms are equally responsible for the light neutrino masses. We show that unless the charged lepton mixing matrix is the identity and the right handed neutrino mass matrix has no phases, we expect sizable lepton flavor violation and electron dipole moment in this region. We use results from recent neutrino oscillation fits, bounds on neutrinoless double beta decay, \(\mu \to e \gamma\), \(\mu \to 3e\), \(\mu \to e\) conversion in nuclei, the muon anomalous magnetic moment, the electron electric dipole moment and cosmology to determine the viability of this region. We derive stringent limits on the heavy neutrino masses and mixing angles as well as on the vacuum expectation value $$v_L$, which drives the type-II seesaw contribution, using the current data. We discuss the perspectives of probing the remaining parameter space by future experiments.

In this Letter, we show that pseudoscalar meson leptonic decay data can be used to set stringent limits on the mass \(m_{W_R}\) of a right-handed vector boson, such as the one that appears in left-right symmetric models. We have shown that for a heavy neutrino with mass \(m_N\) in the range \(50 < m_N/\text{MeV} < 1900\) one can constrain \(m_{W_R} \geq (4-19)~\text{TeV}\) at 90% C.L. This provides the most stringent experimental limit on the \(W_R\) mass to date for this heavy neutrino mass range.

We investigate the possibility of using the Short-Baseline Near Detector (SBND) at Fermilab to constrain lepton flavor violating decays of pions and kaons. We study how to leverage SBND-PRISM, the use of the neutrino beam angular spread to mitigate systematic uncertainties, to enhance this analysis. We show that SBND-PRISM can put stringent limits on the flavor violating branching ratios \(\rm{BR}(\pi^+ \to \mu^+ \nu_e) = 8.9 \times 10^{-4}\), \(\rm{BR}(K^+ \to \mu^+ \nu_e) = 3.2 \times 10^{-3}\), improving previous constraints by factors 9 and 1.25, respectively. We also estimate the SBND-PRISM sensitivity to lepton number violating decays, \(\rm{BR}(\pi^+ \to \mu^+ \overline{\nu}_e)= 2.1 \times 10^{-3}\) and \(\rm{BR}(K^+ \to \mu^+ \overline{\nu}_e) = 7.4 \times 10^{-3}\), though not reaching previous Big European Bubble Chamber (BEBC) limits. Last, we identify several ways how the SBND collaboration could improve this analysis.

The Sun is not quite a perfect sphere, and its oblateness, thought to be induced through its rotation, has been measured using optical observations of its radius. Its gravitational quadrupole moment can then be deduced using solar models, or through helioseismology, and it can also be determined from measurements of its gravitational effects on Mercury’s orbit. The various assessments do not appear to agree, with the most complete and precise orbital assessments being in slight excess of other determinations. This may speak to the existence of a nonluminous disk or ring, where we also note evidence for a circumsolar dust ring within Mercury’s orbit from the Solar TErrestrial RElations Observatory (STEREO) mission. Historically, too, a protoplanetary disk may have been key to reconciling the Sun’s metallicity with its neutrino yield. The distribution of the nonluminous mass within Mercury’s orbit can modify the relative size of the optical and orbital quadrupole moments in different ways. We develop how we can use these findings to limit the mass of a dark disk, ring, or halo in the immediate vicinity of the Sun, and we note how future observational studies of the inner Solar System can not only refine these constraints but can also help to identify and to assess the mass of its dark-matter component.

Heavy neutral leptons (HNLs), depending on their mass and mixing, can be efficiently produced in meson decays from the target or absorber in short- to medium-baseline accelerator neutrino experiments, leaving detectable signals through their decays inside the neutrino detectors. We show that the currently running ICARUS experiment at Fermilab can reconstruct the HNL mass and explore new HNL parameter space in the mass range of 70–190 MeV. The mass reconstruction is enabled by two ingredients: (i) simple two-body kinematics of HNL production from stopped kaon decays at the NuMI absorber, followed by HNL decay into a charged-lepton pair and neutrino at the detector, and (ii) high resolution of Liquid Argon Time Projection Chamber (LArTPC) detectors in reconstructing final state particles. Our mass reconstruction method is robust under realistic energy resolution and angular smearing of the charged leptons, and is applicable to any LArTPC detector. We also discuss the synergy between ICARUS and future facilities like DUNE near detector and PIP-II beam dump in probing the HNL parameter space.

The weak mixing angle provides a sensitive test of the Standard Model. We study SBND’s sensitivity to the weak mixing angle using neutrino-electron scattering events. We perform a detailed simulation, paying particular attention to background rejection and estimating the detector response. We find that SBND can provide a reasonable constraint on the weak mixing angle, achieving 8% precision for \(10^{21}\) protons on target, assuming an overall flux normalization uncertainty of 10%. This result is superior to those of current neutrino experiments and is relatively competitive with other low-energy measurements.

Current data on ultra-high-energy (UHE) cosmic rays suggest they are predominantly made of heavy nuclei. This indicates that the flux of neutrinos produced from proton collisions on the cosmic microwave background is small and hard to observe. Motivated by the recent extremely-high-energy muon event reported by KM3NeT, we explore the possibility of enhancing the energy-flux of cosmogenic neutrinos through nuclear photodisintegration in the presence of new physics. Specifically, we speculate that UHE neutrons may oscillate into a new state, dark (or mirror) neutron \(n'\) that in turn decays injecting large amount of energy to neutrinos, \(n \to n' \to \nu_{\text{UHE}}\). While this mechanism does not explain the tension between the KM3NeT event and null results from IceCube, it reconciles the experimental preference for a heavier cosmic ray composition with a large diffuse cosmogenic flux of UHE neutrinos.

The discovery of ultra-high-energy neutrinos by IceCube marked the beginning of neutrino astronomy. Yet, the origin and production mechanisms of these neutrinos remain open questions. With the recent observation of the highest-energy neutrino event to date by the KM3NeT collaboration, transient sources - astrophysical objects that emit particles in brief, localized bursts - have emerged as promising candidates. In this work, we revisit the identification of such sources in IceCube and future neutrino telescopes, focusing on how both the timing and sky localization of the source affect the detection sensitivity. We highlight the crucial role of the source’s right ascension in determining the effective area of detectors not located at the poles, such as KM3NeT, and present a framework to consistently account for this dependence. As a case study, we investigate evaporating primordial black holes (PBHs) as transient neutrino sources, showing that the detection prospects and localization accuracy are strongly influenced by the PBH’s position in the sky. Our results emphasize the complementarity between neutrino and gamma-ray observatories and showcase the potential of a global network of neutrino detectors to identify and localize transient events that might be missed by traditional photon-based instruments.

A black hole is expected to end its lifetime in a cataclysmic runaway burst of Hawking radiation, emitting all Standard Model particles with ultra-high energies. Thus, the explosion of a nearby primordial black hole (PBH) has been proposed as a possible explanation for the \(\sim 220\)~PeV neutrino-like event recently reported by the KM3NeT collaboration. Assuming a PBH origin, we find that the source would need to lie at a distance of approximately \(4 \times 10^{-5}\)~pc, i.e., within the Solar System, to produce the observed event. At such proximity, the resulting flux of gamma-rays and cosmic rays would be detectable at Earth. By incorporating the time-dependent field of view of gamma-ray observatories, we show that LHAASO should have recorded on the order of \({\cal O}(10^8)\) events between fourteen and seven hours prior to the KM3NeT detection. IceCube should also have detected about 100 events at the time of the burst. The absence of any such multi-messenger signal, particularly in gamma-ray data, strongly disfavors the interpretation of the KM3-230213A event as arising from evaporation in a minimal four-dimensional Schwarzschild scenario.

We explore the neutrino sector of the minimal left-right symmetric model, with the additional charge conjugation discrete symmetry, in the novel regime where type-I and type-II seesaw mechanisms are equally responsible for the light neutrino masses, which can result in large active-sterile mixing. We show that unless the charged lepton mixing matrix is the identity and the right handed neutrino mass matrix has no phases, we expect sizable lepton flavor violation and electron dipole moment in this region. We use recent results from neutrino oscillation fits, bounds on neutrinoless double beta decay, \(\mu \to e \gamma\), \(\mu \to 3e\), \(\mu \to e\) conversion in nuclei, the muon anomalous magnetic moment, the electron electric dipole moment, the CDF II determination of the \(W\) boson mass and cosmology to determine the viability of this region. We derive stringent limits on the heavy neutrino masses and mixing angles as well as on the vacuum expectation value, which drives the type-II seesaw contribution, using the current data. We discuss the perspectives of probing the remaining parameter space by future experiments.

In this talk we show that pseudoscalar meson leptonic decay data can be used to set stringent limits on the mass \(m_{W_R}\) of a right-handed vector boson, such as the one that appears in left-right symmetric models. We have shown that for a heavy neutrino with a mass \(m_N\) in the range \(50<m_N/{\rm MeV} <1900\) one can constraint \(m_{W_R} \gtrsim (4-19)\) TeV at 90% CL. This provides the most stringent experimental limits on the \(W_R\) mass to date for this heavy neutrino mass range.

In this talk we show that pseudoscalar meson leptonic decay data can be used to set stringent limits on the mass \(m_{W_R}\) of a right-handed vector boson, such as the one that appears in left-right symmetric models. We have shown that for a heavy neutrino with a mass \(m_N\) in the range \(50<m_N/{\rm MeV} <1900\) one can constraint \(m_{W_R} \gtrsim (4-19)\) TeV at 90% CL. This provides the most stringent experimental limits on the \(W_R\) mass to date for this heavy neutrino mass range.

In this talk we show that pseudoscalar meson leptonic decay data can be used to set stringent limits on the mass \(m_{W_R}\) of a right-handed vector boson, such as the one that appears in left-right symmetric models. We have shown that for a heavy neutrino with a mass \(m_N\) in the range \(50<m_N/{\rm MeV} <1900\) one can constraint \(m_{W_R} \gtrsim (4-19)\) TeV at 90% CL. This provides the most stringent experimental limits on the \(W_R\) mass to date for this heavy neutrino mass range.

In this talk we show that pseudoscalar meson leptonic decay data can be used to set stringent limits on the mass \(m_{W_R}\) of a right-handed vector boson, such as the one that appears in left-right symmetric models. We have shown that for a heavy neutrino with a mass \(m_N\) in the range \(50<m_N/{\rm MeV} <1900\) one can constraint \(m_{W_R} \gtrsim (4-19)\) TeV at 90% CL. This provides the most stringent experimental limits on the \(W_R\) mass to date for this heavy neutrino mass range.

Neutrino oscillations are a nature given interferometer and as such is a door to better explore the quantum realm. In this work we address the question of how to compute the neutrino wavepacket width from first principles based on decoherence models. We show how the relevant parameters end up fixed solely by the mother particle interactions.

The discovery of ultra-high-energy neutrinos by IceCube marked the beginning of neutrino astronomy. Yet, the origin and production mechanisms of these neutrinos remain open questions. With the recent observation of the highest-energy neutrino event to date by the KM3NeT collaboration, transient sources—astrophysical objects that emit particles in brief, localized bursts—have emerged as promising candidates. In this work, we revisit the identification of such sources in IceCube and future neutrino telescopes, focusing on how both the timing and sky localization of the source affect the detection sensitivity. We highlight the crucial role of the source’s right ascension in determining the effective area of detectors not located at the poles, such as KM3NeT, and present a framework to consistently account for this dependence. As a case study, we investigate evaporating primordial black holes (PBHs) as transient neutrino sources, showing that the detection prospects and localization accuracy are strongly influenced by the PBH’s position in the sky. Our results emphasize the complementarity between neutrino and gamma-ray observatories and showcase the potential of a global network of neutrino detectors to identify and localize transient events that might be missed by traditional photon-based instruments.

In this talk we show that pseudoscalar meson leptonic decay data can be used to set stringent limits on the mass \(m_{W_R}\) of a right-handed vector boson, such as the one that appears in left-right symmetric models. We have shown that for a heavy neutrino with a mass \(m_N\) in the range \(50<m_N/{\rm MeV} <1900\) one can constraint \(m_{W_R} \gtrsim (4-19)\) TeV at 90% CL. This provides the most stringent experimental limits on the \(W_R\) mass to date for this heavy neutrino mass range.

Nesta palestra, discutiremos a importância dos neutrinos para o avanço do nosso entendimento do mundo microscópico. A proposta é oferecer uma visão geral do tema, começando pelas tentativas de compreender o espectro do decaimento beta, passando pela descoberta dos neutrinos e seu papel fundamental na construção do Modelo Padrão, até chegarmos aos problemas em aberto na área. Ao final, comentarei também alguns tópicos que venho estudando com mais profundidade em minha pesquisa.

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This is a description of a teaching experience. You can use markdown like any other post.

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