|
Pedersen, L. G. et al, & Morales, A. I. (2023). First spectroscopic study of odd-odd 78Cu. Phys. Rev. C, 107(4), 044301–10pp.
Abstract: Nuclei in the vicinity of 78Ni are important benchmarks for nuclear structure, which can reveal changes in the shell structure far from stability. Spectroscopy of the odd-odd isotope 78Cu was performed for the first time in an experiment with the EURICA setup at the Radioactive Isotope Beam Factory at RIKEN Nishina Center. Excited states in the neutron-rich isotope were populated following the beta decay of 78Ni produced by in-flight fission and and separated by the BigRIPS separator. A level scheme based on the analysis of γ−γ coincidences is presented. Tentative spin and parity assignments were made when possible based on the β-decay feeding intensities and γ-decay properties of the excited states. Time correlations between β and γ decay show clear indications of an isomeric state with a half-life of 3.8(4) ms. Large-scale Monte Carlo shell-model calculations were performed using the A3DA-m interaction and a valence space comprising the full fp shell and the 1g9/2 and 2d5/2 orbitals for both protons and neutrons. The comparison of the experimental results with the shell-model calculations allows interpreting the excited states in terms of spin multiplets arising from the proton-neutron interaction. The results provide further insight into the evolution of the proton single-particle orbitals as a function of neutron number, and quantitative information about the proton-neutron interaction outside the doubly magic 78Ni core.
|
|
|
Dutka, T. P., & Gargalionis, J. (2023). Dimension-five baryon-number violation in low-scale Pati-Salam models. Phys. Rev. D, 107(3), 035019–10pp.
Abstract: The gauge bosons of the Pati-Salam model do not mediate proton decay at the renormalizable level, and for this reason it is possible to construct scenarios in which SU(4) (R) SU(2)R is broken at relatively low scales. In this paper we show that such low-scale models generate dimension-five operators that can give rise to nucleon decays at unacceptably large rates, even if the operators are suppressed by the Planck scale. We find an interesting complementarity between the nucleon-decay limits and the usual meson-decay constraints. Furthermore, we argue that these operators are generically present when the model is embedded into SO(10), lowering the suppression scale. Under reasonable assumptions, the lower limit on the breaking scale can be constrained to be as high as O(108) GeV.
|
|
|
Abreu, L. M., Dai, L. R., & Oset, E. (2023). J/Psi decay to omega, phi, K*0 plus f0(1370), f0(1710), K0*(1430), f2(1270), f'2 (1525) and K2*(1430): Role of the D-wave for tensor production. Phys. Lett. B, 843, 137999–10pp.
Abstract: We reassess the decay of the J/Psi into an omega, phi, K*0 and one of the f0(1370), f0(1710), f2(1270), f'2 (1525), K0*(1430) and K2*(1430) resonances. We benefit from previous works that considered this reaction as a J/Psi decay into three vector mesons, with a scalar or tensor resonance being formed from the interaction of two of these vectors. The novelty here with respect to former studies is the investigation of the relation between the scalar meson and tensor productions for the first time. To this end, the spin structure of the four vectors present in the production vertex is analyzed, and the D-wave mechanism in the tensor production is included. Then, beyond the ratios studied previously involving scalar states and tensor states independently, new ratios relating the scalar and tensor meson productions are estimated. Our results suggest that the D-wave mechanism of tensor production assumes a relevant contribution. New experimental data reporting the angular distributions of these processes will be important for checking this conclusion.
|
|
|
Gil-Dominguez, F., & Molina, R. (2023). Quark mass dependence of the low-lying charmed mesons at one loop in HH & chi; PT. Phys. Lett. B, 843, 137997–15pp.
Abstract: We study the light and heavy quark mass dependence of the low-lying charmed mesons in the framework of one-loop HH & chi; PT. The low energy constants are determined by analyzing the available lattice data from different LQCD simulations. Model selection tools are implemented to determine the relevant parameters as required by data with a higher precision. Discretization and other effects due to the charm quark mass setting are discussed.
|
|
|
Caron, S., Eckner, C., Hendriks, L., Johannesson, G., Ruiz de Austri, R., & Zaharijas, G. (2023). Mind the gap: the discrepancy between simulation and reality drives interpretations of the Galactic Center Excess. J. Cosmol. Astropart. Phys., 06(6), 013–56pp.
Abstract: The Galactic Center Excess (GCE) in GeV gamma rays has been debated for over a decade, with the possibility that it might be due to dark matter annihilation or undetected point sources such as millisecond pulsars (MSPs). This study investigates how the gamma-ray emission model (-yEM) used in Galactic center analyses affects the interpretation of the GCE's nature. To address this issue, we construct an ultra-fast and powerful inference pipeline based on convolutional Deep Ensemble Networks. We explore the two main competing hypotheses for the GCE using a set of-yEMs with increasing parametric freedom. We calculate the fractional contribution (fsrc) of a dim population of MSPs to the total luminosity of the GCE and analyze its dependence on the complexity of the ryEM. For the simplest ryEM, we obtain fsrc = 0.10 f 0.07, while the most complex model yields fsrc = 0.79 f 0.24. In conclusion, we find that the statement about the nature of the GCE (dark matter or not) strongly depends on the assumed ryEM. The quoted results for fsrc do not account for the additional uncertainty arising from the fact that the observed gamma-ray sky is out-of-distribution concerning the investigated ryEM iterations. We quantify the reality gap between our ryEMs using deep-learning-based One-Class Deep Support Vector Data Description networks, revealing that all employed ryEMs have gaps to reality. Our study casts doubt on the validity of previous conclusions regarding the GCE and dark matter, and underscores the urgent need to account for the reality gap and consider previously overlooked “out of domain” uncertainties in future interpretations.
|
|