arXiv subjects

Pedro Dedin Neto

Publications and source records attributed to Pedro Dedin Neto.

6 recordsLinked to original sources

arXiv2026

Time-of-Flight Constraints on Neutrino Millicharge from Supernova Neutrinos in Galactic Magnetic Fields

A millicharged neutrino propagating through magnetic fields experiences a small Lorentz-force deflection, which induces a geometric time delay. In the ultra-relativistic regime relevant for supernova neutrinos, this delay scales as $q_ν^2 E_ν^{-2}$, where $q_ν$ and $E_ν$ denote the neutrino millicharge and energy, respectively, and thus shares the same leading energy dependence as the standard time-of-flight delay induced by neutrino mass. Motivated by this similarity, we propose a framework to reinterpret supernova time-of-flight limits on neutrino mass as constraints on neutrino millicharge. We express both effects in terms of a common $E_ν^{-2}$ dispersion coefficient and compute the millicharge-induced contribution using a line-of-sight-dependent magnetic delay kernel, extending the original SN1987A uniform-field estimate. Applying this translation to existing SN1987A limits and to projected sensitivities for future Galactic core-collapse supernova observations, we obtain bounds ranging from the $\sim 10^{-17}\, e$ level for SN1987A to the low-$10^{-19}\, e$ regime for next-generation Galactic bursts, with optimistic combinations of detector sensitivity and Galactic sightline approaching $\sim 10^{-20}\, e$. We compare these results with other bounds in the literature and discuss how nonzero neutrino mass affects the interpretation.

hep-ph↗

arXiv2024

Energy Dependence of Flavor Instabilities Stemming from Crossings in the Neutrino Flavor Lepton Number Angular Distribution

In core-collapse supernovae and neutron star mergers, the neutrino density is so large that neutrino-neutrino refraction can lead to flavor conversion, if a zero-crossing is present in the neutrino flavor lepton number (FLN) angular distribution and the neutrino self-interaction strength $μ=\sqrt{2} G_F n_ν$ represents the characteristic timescale of the system. It has been empirically realized that the vacuum frequency $ω=Δm^2/2E$ affects the development of flavor conversion in the presence of zero-crossing even if $ω\ll μ$. Focusing on a homogeneous and axially symmetric neutrino gas, we explore the role of $ω$ in the onset of flavor instabilities. We find that a non-zero vacuum frequency can be responsible for inducing flavor instabilities even when the neutrino self-interaction strength is much larger than the vacuum frequency. Moreover, mapping a neutrino ensemble with $ω\neq 0$ into an effective system with $ω=0$, we find that a system with no FLN zero-crossing can effectively develop one for $ω\neq 0$ becoming unstable.

astro-ph.HE↗

arXiv2023

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

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 $3ν$ mixing. Additionally, we examine the potential energy dependence of quantum decoherence parameters ($Γ= Γ_0 (E/E_0)^n$) with different power laws ($n = 0, 2, 5/2$). 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 $3σ$ bounds of $Γ\leq 6.2 \times 10^{-14}$ eV in the normal mass hierarchy (NH) scenario, while Hyper-K could impose a $2σ$ limit of $Γ\leq 3.6 \times 10^{-14}$ eV for the inverted mass hierarchy (IH) scenario with $n=0$ - assuming no energy exchange between the neutrino subsystem and non-standard environment ($[H,V_p] = 0$). These limits become even more restrictive for a closer Supernova. When we relax the assumption of energy exchange ($[H,V_p] \neq 0$), for a 10 kpc SN, DUNE can establish a $3σ$ limit of $Γ_8 \leq 4.2 \times 10^{-28}$ eV for NH, while Hyper-K could constrain $Γ_8 \leq 1.3 \times 10^{-27}$ eV for IH ($n=0$) with $2σ$, representing the most stringent bounds reported to date. Furthermore, we examine the impact of neutrino loss during propagation for future Supernova detection.

hep-ph↗

arXiv2023

SN1987A neutrino burst: limits on flavor conversion

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 $P_{\overline{e}\overline{e}}$ 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 $1σ$ (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, $P_{\overline{e}\overline{e}}\sim0$ 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.

hep-ph↗

arXiv2023

Open-Source Numerical Solver for Neutrino Collective Effects -- I: Isotropic Neutrino Gas

In this paper, we introduce a new open-source code to find numerical solutions for the neutrino evolution considering neutrino-neutrino interactions, which result in the so-called collective effects. We first describe the theoretical background of this type of evolution, explaining the polarization vector formalism in which we implement our numerical code. We then show the results for different neutrino systems. In this first paper, we focus on the case of an isotropic neutrino gas, exploring a mono-energetic scenario and one with a spectral distribution. The resulting code of this work is available at https://github.com/pedrodedin/Neutrino-Collective-Effects.

hep-ph↗

arXiv2022

Neutrino-(anti)neutrino forward scattering potential for massive neutrinos at low energies

In this work, we calculate expression for the potential due to neutrino-(anti)neutrino forward scattering at low energies ($E< >m_ν$), a representative regime within astrophysical scenarios. There is a broadly used expression for this potential in the literature, which, however, lacks an explicit derivation from basic principles of quantum field theory. Therefore, this paper has the intention to guide the reader through the steps and concepts to derive this potential, trying to be clear and pedagogical. Moreover, we used a rigorous approach concerning the massive nature of the neutrinos, using massive quantized neutrino fields throughout the entire process, while the usual approach is to consider massless neutrino fields at the interaction. In this context, we explicitly show the validity of the massless neutrino fields approximation at the ultra-relativistic regime, as expected. As the last step, we connect the potential expression to the density matrix formalism, which is a usual framework for works considering neutrino-neutrino interactions. We also discuss some theoretical details through the paper, such as the normal ordering of quantum operators and the implications of massive fields in the neutrino state at its production.

hep-ph↗