More Like this

1. Neutron skins: A perspective from dispersive optical models

   https://doi.org/10.3389/fphy.2024.1487314  

   Atkinson, M C; Dickhoff, W H (October 2024, Frontiers in Physics)

   Moreno, O (Ed.)

   An overview of neutron skin predictions obtained using an empirical nonlocal dispersive optical model (DOM) is presented. The DOM links both scattering and bound-state experimental data through a subtracted dispersion relation which allows for fully consistent, data-informed predictions for nuclei where such data exist. Large skins were predicted for both⁴⁸Ca ( $R_{\text{skin}}^{48}=0.25\pm 0.023$fm in 2017) and²⁰⁸Pb ( $R_{\text{skin}}^{208}=0.25\pm 0.05$fm in 2020). Whereas the DOM prediction in²⁰⁸Pb is within 1 $\sigma$of the subsequent PREX-2 measurement, the DOM prediction in⁴⁸Ca is over 2 $\sigma$larger than the thin neutron skin resulting from CREX. From the moment it was revealed, the thin skin in⁴⁸Ca has puzzled the nuclear-physics community as no adequate theories simultaneously predict both a large skin in²⁰⁸Pb and a small skin in⁴⁸Ca. The DOM is unique in its ability to treat both structure and reaction data on the same footing, providing a unique perspective on this $R_{\text{skin}}$puzzle. It appears vital that more neutron data be measured in both the scattering and bound-state domain for⁴⁸Ca to clarify the situation. 

   more » « less
2. Linking Nuclear Reactions and Nuclear Structure to Study Exotic Nuclei Using the Dispersive Optical Model

   https://doi.org/10.1007/978-3-030-58082-7_10  

   Dickhoff, W H (January 2021, Springer proceedings in physics)

   Escher, Jutta et (Ed.)

   The dispersive optical model (DOM) is employed to simultaneously describe elastic nucleon scattering data for 40Ca, 48Ca, and 208Pb as well as observables related to the ground state of these nuclei, with emphasis on the charge density. Such an analysis requires a fully non-local implementation of the DOM including its imaginary component. Illustrations are provided on how ingredients thus generated provide critical components for the description of the (d, p) and (e, e′p) reaction. For the nuclei with N > Z the neutron distribution is constrained by available elastic scattering and ground-state data thereby generating a prediction for the neutron skin. We identify ongoing developments including a non-local DOM analysis for 208Pb and point out possible extensions of the method to secure a successful extension of the DOM to rare isotopes. 

   more » « less
3. The Nuclear Shell Model towards the Drip Lines

   https://doi.org/10.3390/physics4020035  

   Brown, B. Alex (June 2022, Physics)

   Applications of configuration-mixing methods for nuclei near the proton and neutron drip lines are discussed. A short review of magic numbers is presented. Prospects for advances in the regions of four new “outposts” are highlighted: 28O, 42Si, 60Ca and 78Ni. Topics include shell gaps, single-particle properties, islands of inversion, collectivity, neutron decay, neutron halos, two-proton decay, effective charge, and quenching in knockout reactions. 

   more » « less
4. The vacuolar Ca ²⁺ transporter CATION EXCHANGER 2 regulates cytosolic calcium homeostasis, hypoxic signaling, and response to flooding in Arabidopsis thaliana

   https://doi.org/10.1111/nph.19274  

   Bakshi, Arkadipta; Choi, Won‐Gyu; Kim, Su‐Hwa; Gilroy, Simon (September 2023, New Phytologist)

   Summary Flooding represents a major threat to global agricultural productivity and food security, but plants are capable of deploying a suite of adaptive responses that can lead to short‐ or longer‐term survival to this stress. One cellular pathway thought to help coordinate these responses is via flooding‐triggered Ca²⁺signaling.We have mined publicly available transcriptomic data from Arabidopsis subjected to flooding or low oxygen stress to identify rapidly upregulated, Ca²⁺‐related transcripts. We then focused on transporters likely to modulate Ca²⁺signals. Candidates emerging from this analysis includedAUTOINHIBITED Ca²⁺ATPASE 1andCATION EXCHANGER 2. We therefore assayed mutants in these genes for flooding sensitivity at levels from growth to patterns of gene expression and the kinetics of flooding‐related Ca²⁺changes.Knockout mutants inCAX2especially showed enhanced survival to soil waterlogging coupled with suppressed induction of many marker genes for hypoxic response and constitutive activation of others.CAX2mutants also generated larger and more sustained Ca²⁺signals in response to both flooding and hypoxic challenges.CAX2 is a Ca²⁺transporter located on the tonoplast, and so these results are consistent with an important role for vacuolar Ca²⁺transport in the signaling systems that trigger flooding response. 

   more » « less
5. Test of lepton universality in beauty-quark decays

   https://doi.org/10.1038/s41567-021-01478-8  

   Aaij, R.; Beteta, C. Abellán; Ackernley, T.; Adeva, B.; Adinolfi, M.; Afsharnia, H.; Aidala, C. A.; Aiola, S.; Ajaltouni, Z.; Akar, S.; et al (March 2022, Nature Physics)

   Abstract The standard model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton–proton collision data collected with the LHCb detector at CERN’s Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the standard model, such as a new fundamental interaction between quarks and leptons. 

   more » « less