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Journal of Physics G: Nuclear and Particle Physics - latest papers

Latest articles for Journal of Physics G: Nuclear and Particle Physics

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  • Exploring the Ω − spectrum in lattice QCD
    We present an exploratory lattice QCD analysis of the Ω-baryon spectrum. Using a basis of only local smeared three-quark operators in a correlation matrix analysis, we report masses for the ground, first and second excited states of the JP = 1/2±, 3/2± spectra across a broad range in the light quark mass. We investigate the parity and spin quantum numbers for the states observed on the lattice, looking to reconcile these with the resonances encountered in experiment. We find that the Ω−(2012) as reported by the Particle Data Group corresponds to two overlapping resonances with JP = 1/2− and 3/2−. We also propose quantum number assignments for the higher energy resonances, and identify successive radial excitations within the spectra.

  • Future collider sensitivities to νSMEFT interactions
    The discovery of neutrino oscillations and masses provides strong motivation to extend the Standard Model by including right-handed neutrinos, which lead to heavy neutrino states that could exist at the electroweak scale. These states may also be influenced by new high-scale, weakly interacting physics. Incorporating right-handed neutrinos into an effective field theory framework -the νSMEFT- offers a systematic approach to study the phenomenology of heavy neutrinos in current and upcoming experiments. In this work, we present the first prospective 95% exclusion plots achievable at a future lepton collider operating at a center-of-mass energy of for what we term the agnostic νSMEFT scenario. This study focuses on the high-mass regime where the heavy neutrino N decays promptly into leptons and jets. Specifically, we analyse the processes e+e− → νN → νμ−μ+ν and e+e− → νN → νμ−jj, deriving the exclusion regions in the versus mN parameter space. When compared to prospective limits for the LHeC, we find that the semi-leptonic process with final jets in a lepton collider offers the greatest sensitivity, even with a straightforward cut-based analysis. The expected bounds are as stringent as those considered in recent studies for the low-mass regime where the N may be long-lived and detectable via displaced decay searches, both at the LHC and future colliders.

  • Analysis of phase transitions in hot 160−164Dy nuclei
    Phase transitions in hot 160−164Dy isotopes are analyzed using a classification scheme based on the distribution of zeros of the canonical ensemble (CE) partition function in the complex inverse temperature plane. Semi-empirical nuclear level densities (NLD), which are obtained by combining experimental data in the excitation-energy region below the neutron binding energy and the back-shifted Fermi gas model prediction for the high excitation-energy up to 250 MeV, are utilized to determine the CE partition function. Results obtained show that two phase transitions can appear in 160−164Dy isotopes, namely the pairing phase transition and the shape phase transition. The pairing phase transition is found to be of first-order and its critical temperature is ∼0.5 MeV, while the shape phase transition is found to be also of first-order but it occurs at higher temperatures, i.e. around 2.2–2.5 MeV. A comparison between this work and previous ones that involve the same classification scheme but employ purely theoretical NLD has shown a considerable inconsistency. However, our findings should be more conclusive due to various supports from previous theoretical and experimental studies.

  • Emission processes in a self–consistent field
    We present a microscopic description of cluster emission processes within the Cluster–Hartree–Fock self-consistent field theory. The starting point is a Woods–Saxon mean field with spin–orbit and Coulomb terms. Pairing is treated through standard Bardeen–Cooper–Schrieffer quasiparticles. A two-body interaction is introduced as a density-dependent Wigner force having a Gaussian shape with a center of mass (com) correction located in a region of low nuclear density slightly beyond the geometrical contact radius of a system comprised from a nucleus and a surface cluster. We show that such a description adequately reproduces the ground state shape of a spherical nucleus while the surface correction enhances the radial tail of single particle orbitals, thus allowing for a good description of the decay width for unstable systems.

  • Proton induced reaction on 108Cd for astrophysical p-process studies
    The proton capture cross-section of the least abundant proton-rich stable isotope of cadmium, 108Cd (natural abundance 0.89%), has been measured near the Gamow window corresponding to a temperature range of 3–4 GK. The measurement of the total capture reaction cross-section of 108Cd(p,γ)109In was conducted using the activation technique with 66.3% isotopically enriched targets. The cross-section at the lowest energy point of T9 = 3, = 2.26 ± 0.12 MeV, has been reported for the first time. The astrophysical S-factor was measured in the energy range relevant to the astrophysical p-process, between = 2.26 ± 0.12 and 6.84 ± 0.03 MeV. The experimental results have been compared with theoretical predictions of Hauser-Feshbach statistical model calculations using TALYS-1.96. A calculated proton-optical potential was implemented to achieve better fitting, with different combinations of available nuclear level densities (NLDs) and γ-ray strength functions in TALYS-1.96. The calculations provided satisfactory agreement with the experimental results. The reaction rate was extrapolated using the calculated potential in TALYS-1.96 and compared with the values provided in the REACLIB database.