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Nuclear Theory·nucl-th

Friday·March 20, 2026

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 05

    [Submitted on 19 Mar 2026] (cross-list from nucl-ex)

    Single-particle strength toward N = 32: Spectroscopy of 51 Ca via the 50 Ca(d, p) reaction

    C. Ferrera · K. Wimmer · D. Suzuki · N. Imai · A. Jungclaus · T. Miyagi · Y. Utsuno · D. Das · T. Chillery · S. Hanai · J.W. Hwang · N. Kitamura and 39 other authors

    States in the neutron-rich isotope 51 Ca were populated via the 50 Ca(d, p) transfer reaction in inverse kinematics at a beam energy of about 14 AMeV. The experiment was performed using a decelerated radioactive 50 Ca beam from the OEDO facility and the TiNA2 silicon array in combination with the SHARAQ magnetic spectrometer at RIBF/RIKEN. The energies of excited states in 51 Ca were reconstructed via missing mass spectroscopy, and angular distributions of protons were measured to extract differential cross sections. From a comparison with adiabatic distorted wave approximation (ADWA) calculations, spectroscopic factors were deduced for several states, including the ground state and excited states up to 4.2 MeV. These results are compared with shell-model calculations, as well as ab initio valence-space in-medium similarity renormalization group (VS-IMSRG) predictions. The data support the assignment of the 1/2- and 5/2- single-particle states and provide evidence for a candidate 9/2+ state with a structure consistent with neutron excitation into the 0g9/2 orbital. These findings contribute new constraints on the single-particle structure and shell evolution in neutron-rich calcium isotopes.

    Comments:
    PRC accepted
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2603.18632 [pdf]
    PRC(2026)·0 citations
  2. 06

    [Submitted on 19 Mar 2026] (cross-list from hep-ph)

    Probing the Color-Octet Mechanism via Dihadron Fragmentation in Decays

    Zhi-Guo He🇨🇳 · Guanghui Li🇨🇳 · Yu-Jie Tian🇨🇳 · Xin-Kai Wen🇨🇳 · Bin Yan🇨🇳

    The color-octet (CO) mechanism is a cornerstone of non-relativistic QCD, yet its long-distance matrix elements remain limited, preventing stringent tests of the theory. We demonstrate that the Artru-Collins asymmetry in hadronic decays of the -wave bottomonium state provides a direct probe of CO dynamics. The asymmetry arises exclusively from the CO decay channel, whereas the color-singlet (CS) contribution affects only the unpolarized rate, so that a nonzero signal constitutes unambiguous evidence of the CO mechanism. This observable provides a novel way to extract the ratio between CO and CS matrix elements. Focusing on at Belle, we show that the asymmetric beam configuration preserves the asymmetry in the laboratory frame and avoids the strong suppression present in the center-of-mass frame. With the Belle II dataset, could be determined with sufficient precision to address the long-standing discrepancy between the lattice calculations and phenomenological determinations.

    Comments:
    5 pages, 3 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2603.18874 [pdf]
    3 citations
  3. 07

    [Submitted on 19 Mar 2026] (cross-list from hep-ph)

    Transverse spin effects and light-quark dipole moments at colliders

    Xin-Kai Wen · Bin Yan · Zhite Yu · C.-P. Yuan

    In this talk, we present novel methods to investigate light-quark dipole interactions at colliders. Our approach includes: (1) measuring azimuthal asymmetries of a collinear dihadron in semi-inclusive deep inelastic lepton scattering off an unpolarized proton target at the Electron-Ion Collider, and (2) utilizing azimuthal asymmetries of dihadron produced in association with an additional hadron at lepton colliders. These asymmetries provide a unique means to observe transversely polarized quarks, which arise from quantum interference and are exclusively sensitive to dipole interactions at the leading power of the new physics scale. Consequently, they exhibit a linear dependence on the dipole couplings, free from contamination by other new physics effects. This approach has the potential to significantly strengthen current constraints by one to two orders of magnitude. By combining all possible channels of , this novel approach enables the disentanglement of the up- and down-quark dipole moments. Additionally, by controlling the electron's longitudinal polarization and the center-of-mass energy, it separates the contributions mediated by photon and weak boson. Furthermore, it allows for a simultaneous determination of both real and imaginary parts of the dipole couplings, offering a new avenue for investigating potential -violating effects at high energies.

    Comments:
    7 pages, 3 figures. Proceedings for the 26th International Symposium on Spin Physics (SPIN2025), September 21-26, 2025, Qingdao (Tsingtao), Shandong, China
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2603.18951 [pdf]
    0 citations

Affiliations

first authorsco-authorsvia INSPIRE