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Hellgren, M., Papoulias, D. K., & Suhonen, J. (2025). Inelastic neutrino-nucleus scattering off 203/205Tl in terms of the nuclear recoil energy using a hybrid nuclear model. Phys. Lett. B, 868, 139624–7pp.
Abstract: Nuclear structure calculations in the context of a novel hybrid nuclear model, combining the nuclear shell model and the microscopic quasiparticle-phonon model are presented. The predictivity of the hybrid model is tested by computing inelastic neutral-current neutrino-nucleus scattering cross sections off the stable thallium isotopes. The cross sections are presented in terms of the incoming neutrino energy, taking also into account the effect of nuclear recoil energy. Also reported are the expected event rates assuming neutrinos emerging from pion-decay at rest and the diffuse supernova neutrino background. Regarding solar neutrino rates, new results are presented in the context of the hybrid model and compared with previously reported results based solely on nuclear shell model calculations, demonstrating the improved accuracy of the adopted hybrid model at higher neutrino energies.
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ISOLDE Decay Station Collaboration(Mist, J. et al), Algora, A., & Nacher, E. (2025). β- and α-decay spectroscopy of 182Au. Phys. Rev. C, 112(2), 024328–16pp.
Abstract: An alpha- and beta-decay study of a pure source of laser-ionized and mass-separated 182Au (Z = 79, N = 103) was carried out at the ISOLDE Decay Station at the ISOLDE-CERN facility. Detailed gamma-gamma analysis following EC/beta+ decay of 182Au was performed, and the level scheme of daughter nuclide 182Pt was considerably extended via the identification of 125 new levels and 336 new gamma-ray transitions. The nonexistence of a relatively long-lived isomeric state in 182Au and influence of the pandemonium effect on beta-decay feeding intensities are discussed. Differences in feeding for two coexisting bands in 182Pt were investigated. The alpha-decay scheme of 182Au was extended and an alpha-decay branching ratio of 0.129(11)% was measured. Hindrance factors for alpha-decay branches were calculated and I pi = (1+, 2+, 3+) assignment for the 178Ir ground state was proposed.
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KM3NeT Collaboration(Aiello, S. et al), Alves Garre, S., Bariego-Quintana, A., Calvo, D., Cecchini, V., Garcia Soto, A., et al. (2025). gSeaGen code by KM3NeT: An efficient tool to propagate muons simulated with CORSIKA. Comput. Phys. Commun., 314, 109660–15pp.
Abstract: The KM3NeT Collaboration has tackled a common challenge faced by the astroparticle physics community, namely adapting the experiment-specific simulation software to work with the CORSIKA air shower simulation output. The proposed solution is an extension of the open source code gSeaGen, which allows the transport of muons generated by CORSIKA to a detector of any size at an arbitrary depth. The gSeaGen code was not only extended in terms of functionality but also underwent a thorough redesign of the muon propagation routine, resulting in a more accurate and efficient simulation. This paper presents the capabilities of the new gSeaGen code as well as prospects for further developments. Program summary Program title: gSeaGen CPC Library link to program files: https://doi.org/10.17632/ymgxvy2br4.2 Developer's respository link: git.km3net.de/opensource/gseagen Licensing provisions: BSD 3-Clause Programming language: C++ Nature of problem: Integration of the state-of-the-art extensive air shower Monte Carlo event generator CORSIKA [1] into the atmospheric muon simulation for water Cherenkov neutrino telescopes. The primary use case considered is the KM3NeT experiment [2], however, the code should be able to cover other similar experiments as well. The challenges in this work included interfacing the CORSIKA binary output, efficient handling of already generated events to reduce the overall computational cost, and preserving all the additional available information, which can be invaluable in physics analyses. Solution method: The readout of CORSIKA simulation was adapted from the base script provided together with CORSIKA and implemented as a standalone flux driver in gSeaGen. The propagation routine has been redesigned to support the geometry of extensive air shower simulations and to improve its efficiency in propagating particles to the detector. To ensure a reliable modelling of muon energy loss and scattering, PROPOSAL [3] was set as the default internal code for muon transport. PROPOSAL is an open-source software developed and maintained by the IceCube collaboration [4] and is a well-established solution used by the neutrino physics community. Additional comments including restrictions and unusual features: The code was tested with GENIE [5] version 3.4.0 and PROPOSAL 6.1.5. Currently, linking of gSeaGen to GENIE is mandatory, even in the case of a muon-only simulation using CORSIKA.
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Eröncel, C., Gouttenoire, Y., Sato, R., Servant, G., & Simakachorn, P. (2025). Universal Bound on the Duration of a Kination Era. Phys. Rev. Lett., 135(10), 101002–7pp.
Abstract: We show that primordial adiabatic curvature fluctuations generate an instability of the scalar field sourcing a kination era. We demonstrate that the generated higher Fourier modes constitute a radiationlike component dominating over the kination background after about 11 e-folds of cosmic expansion. Current constraints on the extra number of neutrino flavors 0Neff thus imply the observational bound of approximately 10 e-folds, representing the most stringent bound to date on the stiffness of the equation of state of the pre-Big Bang-nucleosynthesis universe.
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Siahmazgi, S. G., Anderson, P. R., & Fabbri, A. (2025). Late-time behavior of scalar field modes for a collapsing null shell spacetime and for the Unruh state in Schwarzschild spacetime. Phys. Rev. D, 112(4), 045013–8pp.
Abstract: The behaviors of the spherically symmetric modes for a massless minimally coupled scalar field are investigated for the Unruh state for Schwarzschild spacetime and the in vacuum state for a spacetime in which a null shell collapses to form a Schwarzschild black hole. In both cases, there are two different sets of solutions to the mode equation that make up the state. For both spacetimes, one set of modes oscillates forever with no damping of the oscillations and the other set approaches zero at late times. The difference between a mode that oscillates forever in the null-shell spacetime and the corresponding mode for the Unruh state at late times vanishes as a power law in time. The modes that approach zero at late times also vanish as a power law in time. In all cases, the power-law damping is preceded by a period of oscillations that appear to be due to quasinormal modes.
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