| |
Wimmer, K. et al, & Huyuk, T. (2026). Precision tests of isospin symmetry through Coulomb excitation of A=62 nuclei. Phys. Lett. B, 876, 140391–6pp.
Abstract: Isospin symmetry in the A = 62 mass system was investigated through Coulomb excitation reactions at the RIKEN Radioactive Isotope Beam Factory. Beams of 62Zn, 62Ga, and 62Ge were studied using the BigRIPS-ZeroDegree-DALI2+ setup under identical experimental conditions, allowing for cancellation of systematic uncertainties. Inelastic scattering cross sections measured with two different targets were used to extract nuclear deformation lengths and E2 matrix elements. The isospin symmetry of the A = 62 system was rigorously tested by examining the linearity of the proton matrix elements within the triplet with high precision. The observed linear relationship between the reduced proton matrix elements for the three nuclei holds within experimental uncertainties, providing a stringent test of isospin symmetry. This experiment provides the most accurate test, to date, of isospin symmetry rules using transition matrix elements. These results were interpreted using large-scale shell-model calculations, offering valuable insights into isospin symmetry behavior in this region of the nuclear chart.
|
|
Donini, A., Gonzalez, M., Hirsch, M., & Neill, N. A. (2026). Leading large Nc contributions to lepton number violating meson decays. Phys. Rev. D, 113(7), 075004–24pp.
Abstract: Lepton number violating meson decays, such as M-1(-) -> M-2(+) l(1)(-)l(2)(-), provide constraints on d = 9 Delta L = 2 operators. Renormalization group equation (RGE)-improved bounds on the Wilson coefficients of these operators have been presented in the literature, taking into account perturbative quantum chromodynamics (QCD) one-loop corrections and the corresponding operator mixing. Here, we present for the first time the contribution of connected diagrams to the hadronic matrix elements < M2 vertical bar Oh vertical bar M-1 >. These diagrams, usually overlooked under the assumption that < M2 vertical bar Oh|M-1 > similar to < M-2 vertical bar J(q3q4)vertical bar 0 > x < 0 vertical bar J(q1q2)vertical bar M-1 > >> < M-2 vertical bar J(q3q2) x J(q1q4 vertical bar)M(1 >), can give indeed a significant contribution to the matrix element. Including these connected diagrams is but the first step toward a full nonperturbative computation of the long-range QCD effects in these operators, that should be performed using lattice field theory techniques. However, connected diagrams represent the leading order in the 1/N-c expansion of the QCD nonperturbative effects and thus our work can be understood as a realistic, first approximation to a complete calculation of the long-range part of the matrix elements.
|
|
DUNE Collaboration(Abbaslu, S. et al), Amar Es-Sghir, H., Amedo, P., Barenboim, G., Benitez Montiel, C., Capo, J., et al. (2026). Identification of low-energy kaons in the ProtoDUNE-SP detector. Phys. Rev. D, 113(5), 052004–21pp.
Abstract: The Deep Underground Neutrino Experiment (DUNE) is a next-generation neutrino experiment with a rich physics program that includes searches for the hypothetical phenomenon of proton decay. Utilizing liquid-argon time-projection chamber technology, DUNE is expected to achieve world-leading sensitivity in the proton decay channels that involve charged kaons in their final states. The first DUNE demonstrator, ProtoDUNE Single-Phase, was a 0.77 kt detector that operated from 2018 to 2020 at the CERN Neutrino Platform, exposed to a mixed hadron and electron test-beam with momenta ranging from 0.3 to 7 GeV/c. We present a selection of low-energy kaons among the secondary particles produced in hadronic reactions, using data from the 6 and 7 GeV/c beam runs. The selection efficiency is 1% and the sample purity 92%. The initial energies of the selected kaon candidates encompass the expected energy range of kaons originating from proton decay events in DUNE (below similar to 200 MeV). In addition, we demonstrate the capability of this detector technology to discriminate between kaons and other particles such as protons and muons, and provide a comprehensive description of their energy loss in liquid argon, which shows good agreement with the simulation. These results pave the way for future proton decay searches at DUNE.
|
|
Dalla Valle Garcia, G., Herrero-Garcia, J., Jones-Perez, J., & Silva-Malpartida, J. (2026). Opening the parameter space of sub-GeV inelastic dark matter through parity violation. J. High Energy Phys., 04(4), 057–44pp.
Abstract: Sub-GeV dark matter (DM) has emerged as a particularly compelling target in light of the persistent null results from conventional DM searches. While s-wave annihilating DM candidates with masses below the GeV are strongly constrained by indirect-detection bounds, inelastic scenarios can naturally evade these limits. In this work, we show that parity violation can play an important role in inelastic DM models featuring long-lived excited states by inducing small diagonal couplings that significantly relax experimental constraints. A precise determination of the excited-state abundance is essential for assessing the phenomenology of such models. To this end, we solve the integrated Boltzmann equation, fully accounting for up- and down-scattering with electrons and positrons as well as dark-sector conversion processes. Using the resulting abundance, we update the viable parameter space in light of the most recent experimental constraints and demonstrate that parity-violating interactions can reopen broad regions of parameter space that would otherwise be excluded. Moreover, the forthcoming LDMX experiment will probe a significant portion of the parameter space. The framework developed in this work can be readily applied to other exothermic sub-GeV DM scenarios.
|
|
ANTARES Collaboration(Albert, A. et al), Alves, S., Calvo, D., Carretero, V., Gozzini, R., Hernandez-Rey, J. J., et al. (2026). Search for diffuse galactic neutrinos with the full ANTARES telescope dataset. J. High Energy Astrophys., 53, 100565–11pp.
Abstract: The diffuse emission of gamma-rays and neutrinos, produced by interactions of cosmic rays with interstellar matter in the Milky Way, provides valuable insights into cosmic ray propagation and Galactic processes. Emission models incorporating different assumptions about cosmic ray diffusion, source distribution, and target gas density are tested using data from neutrino telescopes. In this study, the final all-flavor neutrino dataset, collected over 15 years (2007-2022) by the ANTARES neutrino telescope, is analyzed. A maximum likelihood ratio method built to handle templates of Galactic emission models is employed to evaluate the compatibility of these models with the observed spatial and energy distributions of neutrino events. The results do not yield stringent constraints on the tested models and upper limits on the diffuse neutrino flux are derived, which are compatible with the results obtained by other experiments.
|
|
|
