First results from the JUNO reactor neutrino experiment already determine with world-leading precision the small neutrino squared-mass splitting $$ \Delta {m}_{21}^2 $$ and the mixing angle $\textit{θ}$ . In this article we perform an exploratory study beyond these, taking advantage of the first JUNO data release to discuss its sensitivity to the large squared-mass splitting, $$ \Delta {m}_{3\ell}^2 $$ . When combined with constraints from global oscillation data, this may already contain some information on the neutrino mass ordering. Indeed, we find that the combination of the complementary $$ \Delta {m}_{3\ell}^2 $$ -determinations gives a slight preference for Normal Ordering, with a $\textit{p}$-value for Inverted Ordering of 2%–2.6% (2$\textit{.}$2$\textit{σ}$–2$\textit{.}$3$\textit{σ}$). We study the robustness of this result with respect to potential systematic uncertainties and statistical fluctuations. Taken at face value, a full global analysis of oscillation data including the publicly available JUNO information and data leads to a preference for Normal Ordering with ∆$\textit{χ}$ = 4.6 and 9.4 without and with Super-K and IceCube-24 atmospheric neutrino data, respectively.

Spain

Ivan Esteban

United States

M. Gonzalez-Garcia

Michele Maltoni

United Kingdom

Ivan Martinez-Soler

China

João Pinheiro

Germany

Thomas Schwetz

Lessons from the first JUNO results

We perform a global analysis of most up-to-date solar neutrino data and KamLAND reactor antineutrino data in the framework of the 3+1 sterile neutrino mixing scenario (invoked to explain the results of the Gallium source experiments) with the aim of quantifying the dependence of the (in)compatibility of the required mixing with assumptions on the initial fluxes. The analysis of solar data is performed in two alternative ways: using the flux predicted by the latest standard solar models, and in a model independent approach where the solar fluxes are also determined by the fit. The dependence on the normalization of the capture rate in the solar Gallium experiments is also quantified. Similarly, in the KamLAND analysis we consider both the case where the reactor flux normalization is assumed to be known <italic>a priori</italic>, as well as a normalization free case which relies solely on available neutrino data. Using a parameter goodness of fit test, we find that in most cases the compatibility between Gallium and solar+KamLAND data only occur at the 3 <italic>&#963;</italic> level or higher. We also discuss the implications of enforcing better compatibility by tweaking the mechanism for the energy production in the Sun.

M.C. Gonzalez-Garcia

João Paulo Pinheiro

Solar model independent constraints on the sterile neutrino interpretation of the Gallium Anomaly

We present an updated global analysis of neutrino oscillation data as of September 2024. The parameters $\textit{θ}$ , $\textit{θ}$ , $$ \Delta {m}_{21}^2 $$ , and $$ \mid \Delta {m}_{3\ell}^2\mid $$ ($\textit{ℓ}$ = 1$\textit{,}$ 2) are well-determined with relative precision at 3$\textit{σ}$ of about 13%, 8%, 15%, and 6%, respectively. The third mixing angle $\textit{θ}$ still suffers from the octant ambiguity, with no clear indication of whether it is larger or smaller than 45 . The determination of the leptonic CP phase $\textit{δ}$ depends on the neutrino mass ordering: for normal ordering the global fit is consistent with CP conservation within 1$\textit{σ}$, whereas for inverted ordering CP-violating values of $\textit{δ}$ around 270$\textit{°}$ are favored against CP conservation at more than 3$\textit{.}$6$\textit{σ}$. While the present data has in principle 2$\textit{.}$5–3$\textit{σ}$ sensitivity to the neutrino mass ordering, there are different tendencies in the global data that reduce the discrimination power: T2K and NOvA appearance data individually favor normal ordering, but they are more consistent with each other for inverted ordering. Conversely, the joint determination of $$ \mid \Delta {m}_{3\ell}^2\mid $$ from global disappearance data prefers normal ordering. Altogether, the global fit including long-baseline, reactor and IceCube atmospheric data results into an almost equally good fit for both orderings. Only when the $\textit{χ}$ table for atmospheric neutrino data from Super-Kamiokande is added to our $\textit{χ}$ , the global fit prefers normal ordering with ∆$\textit{χ}$ = 6$\textit{.}$1. We provide also updated ranges and correlations for the effective parameters sensitive to the absolute neutrino mass from $\textit{β}$-decay, neutrinoless double-beta decay, and cosmology.

NuFit-6.0: updated global analysis of three-flavor neutrino oscillations

We quantify the effects of light spin-zero particles with pseudoscalar couplings to leptons and scalar couplings to nucleons on the evolution of solar neutrinos. In this scenario the matter potential sourced by the nucleons in the Sun’s matter gives rise to spin precession of the relativistic neutrino ensemble. As such the effects in the solar observables are different if neutrinos are Dirac or Majorana particles. For Dirac neutrinos the spin-flavour precession results into left-handed neutrino to right-handed neutrino (i.e., active-sterile) oscillations, while for Majorana neutrinos it results into left-handed neutrino to right-handed antineutrino (i.e., active-active) oscillations. In both cases this leads to distortions in the solar neutrino spectrum which we use to derive constraints on the allowed values of the mediator mass and couplings via a global analysis of the solar neutrino data. In addition for Majorana neutrinos spin-flavour precession results into a potentially observable flux of solar electron antineutrinos at the Earth which we quantify and constrain with the existing bounds from Borexino and KamLAND.

Iran

Saeed Ansarifard

Solar neutrinos and leptonic spin forces

We determine the solar neutrino fluxes from the global analysis of the most up-to-date terrestrial and solar neutrino data including the final results of the three phases of Borexino. The analysis are performed in the framework of three-neutrino mixing with and without accounting for the solar luminosity constraint. We discuss the independence of the results on the input from the Gallium experiments. The determined fluxes are then compared with the predictions provided by the latest Standard Solar Models. We quantify the dependence of the model comparison with the assumptions about the normalization of the solar neutrino fluxes produced in the CNO-cycle as well as on the particular set of fluxes employed for the model testing.

Aldo Serenelli

Status of direct determination of solar neutrino fluxes after Borexino

In this note we describe how to complement the neutrino evolution matrix calculated at a given energy and trajectory with additional information which allows to reliably extrapolate it to nearby energies or trajectories without repeating the full computation. Our method works for arbitrary matter density profiles, can be applied to any propagation model described by an Hamiltonian, and exactly guarantees the unitarity of the evolution matrix. As a straightforward application, we show how to enhance the calculation of the theoretical predictions for experimentally measured quantities, so that they remain accurate even in the presence of fast neutrino oscillations. Furthermore, the ability to “move around” a given energy and trajectory opens the door to precise interpolation of the oscillation amplitudes within a grid of tabulated values, with potential benefits for the computation speed of Monte-Carlo codes. We also provide a set of examples to illustrate the most prominent features of our approach.

From ray to spray: augmenting amplitudes and taming fast oscillations in fully numerical neutrino codes

We derive new constraints on effective four-fermion neutrino non-standard interactions with both quarks and electrons. This is done through the global analysis of neutrino oscillation data and measurements of coherent elastic neutrino-nucleus scattering (CEνNS) obtained with different nuclei. In doing so, we include not only the effects of new physics on neutrino propagation but also on the detection cross section in neutrino experiments which are sensitive to the new physics. We consider both vector and axial-vector neutral-current neutrino interactions and, for each case, we include simultaneously all allowed effective operators in flavour space. To this end, we use the most general parametrization for their Wilson coefficients under the assumption that their neutrino flavour structure is independent of the charged fermion participating in the interaction. The status of the LMA-D solution is assessed for the first time in the case of new interactions taking place simultaneously with up quarks, down quarks, and electrons. One of the main results of our work are the presently allowed regions for the effective combinations of non-standard neutrino couplings, relevant for long-baseline and atmospheric neutrino oscillation experiments.

Pilar Coloma

Salvador Urrea

Global constraints on non-standard neutrino interactions with quarks and electrons

Erratum to: Constraining new physics with Borexino Phase-II spectral data

Erratum to: Neutrino oscillation constraints on U(1)′ models: from non-standard interactions to long-range forces

We present a detailed analysis of the spectral data of Borexino Phase II, with the aim of exploiting its full potential to constrain scenarios beyond the Standard Model. In particular, we quantify the constraints imposed on neutrino magnetic moments, neutrino non-standard interactions, and several simplified models with light scalar, pseudoscalar or vector mediators. Our analysis shows perfect agreement with those performed by the collaboration on neutrino magnetic moments and neutrino non-standard interactions in the same restricted cases and expands beyond those, stressing the interplay between flavour oscillations and flavour non-diagonal interaction effects for the correct evaluation of the event rates. For simplified models with light mediators we show the power of the spectral data to obtain robust limits beyond those previously estimated in the literature.