arXiv subjects

Mariam Tórtola

Publications and source records attributed to Mariam Tórtola.

18 recordsLinked to original sources

arXiv2025

Neutrino magnetic moments: effective versus fundamental parameters

The search for neutrino magnetic moments offers a valuable window into physics beyond the Standard Model. However, a common misconception arises in the interpretation of experimental results: the assumption that the so-called effective neutrino magnetic moment is a universal, experiment-independent quantity. In reality, this effective parameter depends on the specific characteristics of each experiment, including the neutrino source, flavor composition or energy spectrum. As a result, the effective magnetic moment derived from solar neutrino data differs fundamentally from that obtained in reactor or accelerator-based experiments. Treating these quantities as directly comparable can lead to misleading conclusions. In this work, we clarify the proper definition of the effective neutrino magnetic moment in various experimental contexts and discuss the implications of this misconception for global analyses and theoretical interpretations.

hep-ph↗

arXiv2024

Neutrino electromagnetic properties and sterile dipole portal in light of the first solar CE$ν$NS data

Despite being neutral particles, neutrinos can acquire non-zero electromagnetic properties from radiative corrections that can be induced by the presence of new physics. Electromagnetic neutrino processes induce spectral distortions in neutrino scattering data, which are especially visible at experiments characterized by low recoil thresholds. We investigate how neutrino electromagnetic properties confront the recent indication of coherent elastic neutrino-nucleus scattering (CE$ν$NS) from $^8$B solar neutrinos in dark matter direct detection experiments. We focus on three possibilities: neutrino magnetic moments, neutrino electric charges, and the active-sterile transition magnetic moment portal. We analyze recent XENONnT and PandaX-4T data and infer the first \cevns-based constraints on electromagnetic properties using solar $^8$B neutrinos.

hep-ph↗

arXiv2024

The Sun and core-collapse supernovae are leading probes of the neutrino lifetime

The large distances travelled by neutrinos emitted from the Sun and core-collapse supernovae together with the characteristic energy of such neutrinos provide ideal conditions to probe their lifetime, when the decay products evade detection. We investigate the prospects of probing invisible neutrino decay capitalising on the detection of solar and supernova neutrinos as well as the diffuse supernova neutrino background (DSNB) in the next-generation neutrino observatories Hyper-Kamiokande, DUNE, JUNO, DARWIN, and RES-NOVA. We find that future solar neutrino data will be sensitive to values of the lifetime-to-mass ratio $τ_1/m_1$ and $τ_2/m_2$ of $\mathcal{O}(10^{-1} - 10^{-2})$ s/eV. From a core-collapse supernova explosion at $10$ kpc, lifetime-to-mass ratios of the three mass eigenstates of $\mathcal{O}(10^5)$ s/eV could be tested. After $20$ years of data taking, the DSNB would extend the sensitivity reach of $τ_1/m_1$ to $10^{8}$ s/eV. These results promise an improvement of about $6 -15$ orders of magnitude on the values of the decay parameters with respect to existing limits.

astro-ph.HE↗

arXiv2023

Synergy between cosmological and laboratory searches in neutrino physics

The intersection of the cosmic and neutrino frontiers is a rich field where much discovery space still remains. Neutrinos play a pivotal role in the hot big bang cosmology, influencing the dynamics of the universe over numerous decades in cosmological history. Recent studies have made tremendous progress in understanding some properties of cosmological neutrinos, primarily their energy density. Upcoming cosmological probes will measure the energy density of relativistic particles with higher precision, but could also start probing other properties of the neutrino spectra. When convolved with results from terrestrial experiments, cosmology can become even more acute at probing new physics related to neutrinos or even Beyond the Standard Model (BSM). Any discordance between laboratory and cosmological data sets may reveal new BSM physics and/or suggest alternative models of cosmology. We give examples of the intersection between terrestrial and cosmological probes in the neutrino sector, and briefly discuss the possibilities of what different laboratory experiments may see in conjunction with cosmological observatories.

hep-ph↗

arXiv2023

Neutrino CPT violation in the solar sector

In this paper we place new bounds on CPT violation in the solar neutrino sector analyzing the results from solar experiments and KamLAND. We also discuss the sensitivity of the next-generation experiments DUNE and Hyper-Kamiokande, which will provide accurate measurements of the solar neutrino oscillation parameters. The joint analysis of both experiments will further improve the precision due to cancellations in the systematic uncertainties regarding the solar neutrino flux. In combination with the next-generation reactor experiment JUNO, the bound on CPT violation in the solar sector could be improved by one order of magnitude in comparison with current constraints. The distinguishability among CPT-violating neutrino oscillations and neutrino non-standard interactions in the solar sector is also addressed.

hep-ph↗

arXiv2022

Non-unitary three-neutrino mixing in the early Universe

Deviations from unitarity in the three-neutrino mixing canonical picture are expected in many physics scenarios beyond the Standard Model. The mixing of new heavy neutral leptons with the three light neutrinos would in principle modify the strength and flavour structure of charged-current and neutral-current interactions with matter. Non-unitarity effects would therefore have an impact on the neutrino decoupling processes in the early Universe and on the value of the effective number of neutrinos, $N_{\rm eff}$. We calculate the cosmological energy density in the form of radiation with a non-unitary neutrino mixing matrix, addressing the possible interplay between parameters. Highly accurate measurements of $N_{\rm eff}$ from forthcoming cosmological observations can provide independent and complementary limits on the departures from unitarity. For completeness, we relate the scenario of small deviations from unitarity to non-standard neutrino interactions and compare the forecasted constraints to other existing limits in the literature.

hep-ph↗

arXiv2022

Neutrino mass and mass ordering: No conclusive evidence for normal ordering

The extraction of the neutrino mass ordering is one of the major challenges in particle physics and cosmology, not only for its implications for a fundamental theory of mass generation in nature, but also for its decisive role in the scale of future neutrinoless double beta decay experimental searches. It has been recently claimed that current oscillation, beta decay and cosmological limits on the different observables describing the neutrino mass parameter space provide robust decisive Bayesian evidence in favor of the normal ordering of the neutrino mass spectrum [arXiv:2203.14247]. We further investigate these strong claims using a rich and wide phenomenology, with different sampling techniques of the neutrino parameter space. Contrary to the findings of Jimenez et al [arXiv:2203.14247], no decisive evidence for the normal mass ordering is found. Neutrino mass ordering analyses must rely on priors and parameterizations that are ordering-agnostic: robust results should be regarded as those in which the preference for the normal neutrino mass ordering is driven exclusively by the data, while we find a difference of up to a factor of 33 in the Bayes factors among the different priors and parameterizations exploited here. An ordering-agnostic prior would be represented by the case of parameterizations sampling over the two mass splittings and a mass scale, or those sampling over the individual neutrino masses via normal prior distributions only. In this regard, we show that the current significance in favor of the normal mass ordering should be taken as $2.7σ$ (i.e. moderate evidence), mostly driven by neutrino oscillation data.

hep-ph↗

arXiv2021

Signatures of primordial black hole dark matter at DUNE and THEIA

Primordial black holes (PBHs) are a potential dark matter candidate whose masses can span over many orders of magnitude. If they have masses in the $10^{15}-10^{17}$ g range, they can emit sizeable fluxes of MeV neutrinos through evaporation via Hawking radiation. We explore the possibility of detecting light (non-)rotating PBHs with future neutrino experiments. We focus on two next generation facilities: the Deep Underground Neutrino Experiment (DUNE) and THEIA. We simulate the expected event spectra at both experiments assuming different PBH mass distributions and spins, and we extract the expected 95% C.L. sensitivities to these scenarios. Our analysis shows that future neutrino experiments like DUNE and THEIA will be able to set competitive constraints on PBH dark matter, thus providing complementary probes in a part of the PBH parameter space currently constrained mainly by photon data.

hep-ph↗

arXiv2021

Cosmological radiation density with non-standard neutrino-electron interactions

Neutrino non-standard interactions (NSI) with electrons are known to alter the picture of neutrino decoupling from the cosmic plasma. NSI modify both flavour oscillations through matter effects, and the annihilation and scattering between neutrinos and electrons and positrons in the thermal plasma. In view of the forthcoming cosmological observations, we perform a precision study of the impact of non-universal and flavour-changing NSI on the effective number of neutrinos, $N_{eff}$. We present the variation of $N_{eff}$ arising from the different NSI parameters and discuss the existing degeneracies among them, from cosmology alone and in relation to the current bounds from terrestrial experiments. Even though cosmology is generally less sensitive to NSI than these experiments, we find that future cosmological data would provide competitive and complementary constraints for some of the couplings and their combinations.

hep-ph↗

arXiv2020

CPT and CP, an entangled couple

Even though it is undoubtedly very appealing to interpret the latest T2K results as evidence of CP violation, this claim assumes CPT conservation in the neutrino sector to an extent that has not been tested yet. As we will show, T2K results are not robust against a CPT-violating explanation. On the contrary, a CPT-violating CP-conserving scenario is in perfect agreement with current neutrino oscillation data. Therefore, to elucidate whether T2K results imply CP or CPT violation is of utter importance. We show that, even after combining with data from NO$ν$A and from reactor experiments, no claims about CP violation can be made. Finally, we update the bounds on CPT violation in the neutrino sector.

hep-ph↗

arXiv2020

Probing new neutral gauge bosons with CEvNS and neutrino-electron scattering

The potential for probing extra neutral gauge boson mediators ($Z^\prime$) from low-energy measurements is comprehensively explored. Our study mainly focuses on $Z^\prime$ mediators present in string-inspired $E_6$ models and left-right symmetry. We estimate the sensitivities of coherent-elastic neutrino-nucleus scattering (CE$ν$NS) and neutrino-electron scattering experiments. Our results indicate that such low-energy high-intensity measurements can provide a valuable probe, complementary to high-energy collider searches and electroweak precision measurements.

hep-ph↗

arXiv2020

High-energy constraints from low-energy neutrino non-standard interactions

Many scenarios of new physics predict the existence of neutrino Non-Standard Interactions, new vector contact interactions between neutrinos and first generation fermions beyond the Standard Model. We obtain model-independent constraints on the Standard Model Effective Field Theory at high energies from bounds on neutrino non-standard interactions derived at low energies. Our analysis explores a large set of new physics scenarios and includes full one-loop running effects below and above the electroweak scale. Our results show that neutrino non-standard interactions already push the scale of new physics beyond the TeV. We also conclude that bounds derived by other experimental probes, in particular by low-energy precision measurements and by charged lepton flavor violation searches, are generally more stringent. Our study constitutes a first step towards the systematization of phenomenological analyses to evaluate the impact of neutrino Non-Standard Interactions for new physics scenarios at high energies.

hep-ph↗

arXiv2019

Neutrino Mass Ordering at DUNE: an Extra $ν$-Bonus

We study the possibility of extracting the neutrino mass ordering at the future Deep Underground Neutrino Experiment using atmospheric neutrinos, which will be available before the muon neutrino beam starts being perational. The large statistics of the atmospheric muon neutrino and antineutrino samples at the far detector, together with the baselines of thousands of kilometers that these atmospheric (anti)neutrinos travel, provide the ideal ingredients to extract the neutrino mass ordering via matter effects in the neutrino propagation through the Earth. Crucially, muon capture by Argon provides excellent charge-tagging, allowing to disentangle the neutrino and antineutrino signature. This is a critical extra benefit of having a Liquid Argon Time Projection Chamber as far detector, that could render a $4σ$ extraction of the mass ordering after ten years of exposure.

hep-ph↗

arXiv2019

New physics vs new paradigms: distinguishing CPT violation from NSI

Our way of describing Nature is based on local relativistic quantum field theories, and then CPT symmetry, a natural consequence of Lorentz invariance, locality and hermiticity of the Hamiltonian, is one of the few if not the only prediction that all of them share. Therefore, testing CPT invariance does not test a particular model but the whole paradigm. Current and future long baseline experiments will assess the status of CPT in the neutrino sector at an unprecedented level and thus its distinction from similar experimental signatures arising from non-standard interactions is imperative. Whether the whole paradigm is at stake or just the standard model of neutrinos crucially depends on that.

hep-ph↗

arXiv2018

Exploring the intrinsic Lorentz-violating parameters at DUNE

Neutrinos can push our search for new physics to a whole new level. What makes them so hard to be detected, what allows them to travel humongous distances without being stopped or deflected allows to amplify Planck suppressed effects (or effects of comparable size) to the level we can measure or bound in DUNE. In this work we analyse the sensitivity of DUNE to CPT and Lorentz--violating interactions in a framework that allows a straightforward extrapolation of the bounds obtained to any phenomenological modification of the dispersion relation of neutrinos.

hep-ph↗

arXiv2018

Zooming in on neutrino oscillations with DUNE

We examine the capabilities of the DUNE experiment as a probe of the neutrino mixing paradigm. Taking the current status of neutrino oscillations and the design specifications of DUNE, we determine the experiment's potential to probe the structure of neutrino mixing and CP violation. We focus on the poorly determined parameters $θ_{23}$ and $δ_{CP}$ and consider both two and seven years of run. We take various benchmarks as our true values, such as the current preferred values of $θ_{23}$ and $δ_{CP}$, as well as several theory-motivated choices. We determine quantitatively DUNE's potential to perform a precision measurement of $θ_{23}$, as well as to test the CP violation hypothesis in a model-independent way. We find that, after running for seven years, DUNE will make a substantial step in the precise determination of these parameters, bringing to quantitative test the predictions of various theories of neutrino mixing.

hep-ph↗

arXiv2018

Neutrinos, DUNE and the world best bound on CPT invariance

CPT symmetry, the combination of Charge Conjugation, Parity and Time reversal, is a cornerstone of our model building strategy and therefore the repercussions of its potential violation will severely threaten the most extended tool we currently use to describe physics, i.e. local relativistic quantum fields. However, limits on its conservation from the Kaon system look indeed imposing. In this work we will show that neutrino oscillation experiments can improve this limit by several orders of magnitude and therefore are an ideal tool to explore the foundations of our approach to Nature. Strictly speaking testing CPT violation would require an explicit model for how CPT is broken and its effects on physics. Instead, what is presented in this paper is a test of one of the predictions of CPT conservation, i.e., the same mass and mixing parameters in neutrinos and antineutrinos. In order to do that we calculate the current CPT bound on all the neutrino mixing parameters and study the sensitivity of the DUNE experiment to such an observable. After deriving the most updated bound on CPT from neutrino oscillation data, we show that, if the recent T2K results turn out to be the true values of neutrino and antineutrino oscillations, DUNE would measure the fallout of CPT conservation at more than 3$σ$. Then, we study the sensitivity of the experiment to measure CPT invariance in general, finding that DUNE will be able to improve the current bounds on $Δ(Δm^2_{31})$ by at least one order of magnitude. We also study the sensitivity to the other oscillation parameters. Finally we show that, if CPT is violated in nature, combining neutrino with antineutrino data in oscillation analysis will produce imposter solutions.

hep-ph↗

arXiv2011

Global neutrino data and recent reactor fluxes: status of three-flavour oscillation parameters

We present the results of a global neutrino oscillation data analysis within the three-flavour framework. We include latest results from the MINOS long-baseline experiment (including electron neutrino appearance as well as anti-neutrino data), updating all relevant solar (SK II+III), atmospheric (SK I+II+III) and reactor (KamLAND) data. Furthermore, we include a recent re-calculation of the anti-neutrino fluxes emitted from nuclear reactors. These results have important consequences for the analysis of reactor experiments and in particular for the status of the mixing angle $θ_{13}$. In our recommended default analysis we find from the global fit that the hint for non-zero $θ_{13}$ remains weak, at 1.8$σ$ for both neutrino mass hierarchy schemes. However, we discuss in detail the dependence of these results on assumptions concerning the reactor neutrino analysis.

hep-ph↗