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Giarnetti, A., Marciano, S., & Meloni, D. (2026). Constraining the Neutrino Mixing Matrix via Single-Sector Charged-Lepton Rotations in the JUNO Precision Era. Symmetry-Basel, 18(6), 954–18pp.
Abstract: The unprecedented precision now being achieved in the measurement of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) lepton mixing matrix opens a new window onto the underlying structure of the neutrino mass matrix and the possibly associated flavor symmetries. In this work, we investigate the constraints imposed on the unitary matrix U nu that diagonalizes the neutrino mass matrix, under the hypothesis that the charged-lepton mixing matrix Ul consists of a single two-by-two rotation in one of the three sectors: (1,2), (1,3), or (2,3). For this analysis, we considered the latest global fit, which incorporates the precision measurement of theta 12 from the JUNO experiment. For each scenario, we also derive analytical expressions for the entries of U nu in terms of the measured PMNS parameters to obtain compact sum-rule-like formulae.
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Lerendegui-Marco, J. et al, Balibrea-Correa, J., Babiano-Suarez, V., Domingo-Pardo, C., de la Fuente-Rosales, G., Gameiro, B., et al. (2026). Direct Experiments of Neutron Capture on Stable and Unstable Isotopes for Stellar Nucleosynthesis Studies. Galaxies, 14(3), 59–26pp.
Abstract: Neutron capture reactions provide essential nuclear physics input for modeling the synthesis of heavy elements in stars. The growing precision of stellar spectroscopy and isotopic measurements in presolar SiC grains now demands cross sections with improved accuracy over the full energy range, and access to unstable nuclei relevant to slow (s-) process branchings and the intermediate (i-) process. This article reviews recent progress in direct neutron capture measurements, focusing on time-of-flight (TOF) experiments at CERN n_TOF and complementary activation techniques. Substantial advances have been achieved for stable s-only and bottleneck isotopes, significantly improving constraints on s-process models. In parallel, the combination of high instantaneous neutron fluxes and advanced detector systems has facilitated first-time neutron capture measurements on several radioactive branching-point nuclei. Feasibility studies, however, reveal current limitations related to sample availability, background conditions, and restricted energy coverage. In this context, the complementarity between TOF and activation emerges as a central strategy. Future developments, including high-flux facilities and novel inverse kinematics experiments in ion storage rings, are expected to extend the boundaries of neutron capture measurements, overcoming current limitations and helping unlock new frontiers in our understanding of stellar nucleosynthesis.
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Saxena, G., Sikhwal, H., Chandnani, N., Parab, P., Parashari, S., Llosa, G., et al. (2026). Impact of shape coexistence on nuclear stability. Phys. Lett. B, 879, 140621–7pp.
Abstract: Nuclear decay properties are conventionally predicted assuming nuclei decay from their ground-state configurations. However, this often neglects a fundamental structural complexity which is the phenomenon of shape coexistence, where nuclei possess multiple competing configurations at nearly degenerate energies. When both parent and daughter nuclei can exist in different energy minima, multiple decay pathways become possible. We systematically investigate how shape coexistence influences nuclear decay for approximately 1500 even-even nuclei (8 <= Z <= 118, 8 <= N <= 184) using the Nilsson-Strutinsky method and relativistic mean-field calculations with NL3*, DD-ME2, and DD-PC1 functionals. We identify around 400 nuclei exhibiting competing energy minima separated by less than 1 MeV. For these shape-coexisting nuclei, we calculate a, /i+ and /i-decay half-lives considering all possible transition pathways between the competing minima. Our results demonstrate that shape coexistence substantially impacts decay predictions, with half-lives showing variations up to nearly one logarithmic unit depending on which configurations participate in the transition. Comparison with experimental data from NUBASE2020 shows that pathways involving the second minimum sometimes reproduce measured lifetimes more closely than conventional ground-state to ground-state assumptions. Branching ratios exhibit even stronger sensitivity, with certain nuclei displaying complete inversions of the dominant decay mode depending on configuration choice. These pathway-dependent variations are not due to model uncertainties but reflect inherent structural effects. The correlation between the shape dynamics and nuclear stability establishes the shape coexistence as an essential component in predictive nuclear structure and astrophysics studies.
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Perez de Leon, M. A., Ochoa-Oregon, S. A., Renteria-Estrada, D. F., & Hernandez-Pinto, R. J. (2026). Phenomenological Extraction of Fragmentation Functions in a pp¯ Environment. Few-Body Syst., 67(3), 44–18pp.
Abstract: The precise determination of fragmentation functions (FFs) of hadrons relies on the accurate description of the differential cross sections obtained from both experimental high-energy hadron colliders and theoretical predictions at higher orders in quantum chromodynamics. Various phenomenological strategies have been employed to extract FFs. In this work, we analyze the use of kinematical cuts for reactions including pions and kaons in proton-antiproton collisions to isolate individual FF contributions. This study examines the feasibility of using a similar approach as in proton-proton colliders to analyze FF flavour separation [1]. In particular, we study photon-hadron production at colliders, including NLO QCD and LO QED corrections to reconstruct the partonic momentum fractions.
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Encarnacion, P., Feijoo, A., & Oset, E. (2026). Scattering observables and correlation function for p f1(1285) revisited. Phys. Rev. D, 113(11), L111502–8pp.
Abstract: In view of the recent theoretical developments in the fixed center approximation for the scattering of a particle with a a two-body cluster, implementing elastic unitarity on the standard fixed center formalism, and the imminent availability of ALICE data on the correlation function of the p f1(1285) system, we update the results of a previous work for this correlation function and the low-energy scattering observables. The new results show appreciable changes in some observables and should provide valuable input for comparison with the forthcoming experimental data. Such a comparison is expected to yield relevant information on the nature of the axial-vector meson states.
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