Nuclear Theory·nucl-th

Thursday·July 16, 2026

9 papers—6 primary·3 cross-listed

07
[Submitted on 15 Jul 2026] (cross-list from hep-ph)
Weak charged current induced electron and positron scattering off proton at JLab and MAMI energies
A. Fatima🇮🇳 · M. Sajjad Athar🇮🇳 · S. K. Singh🇮🇳
The development of next-generation, high-luminosity, and high-precision charged lepton beam facilities at JLab and MAMI has opened, in recent years, a new frontier in the exploration of weak interaction processes induced by electrons and positrons in the neutral current sector, which can also be used to study weak interaction processes induced by charged currents. In particular, these processes in the intermediate energy regime, spanning from a few hundred MeV to a few GeV, play a crucial role in understanding electroweak dynamics, nucleon structure, and hadronic response functions. This review presents a comprehensive theoretical study of weak charged-current interactions of electrons and positrons with free protons, encompassing quasielastic scattering in both the strangeness conserving and strangeness changing channels, together with inelastic production of the $P_{33}$ (1232), $P_{11}$ (1440), $S_{11}$ (1535) resonances, $η$ and $K$ mesons, and associated production of strange particles. We analyse differential and total cross sections, polarization observables of the final baryons, and spin asymmetries of the proton target, demonstrating their sensitivity to the underlying weak interaction dynamics and to possible second class currents, thereby enabling stringent tests of G- and T- invariance. The explored kinematic region also offers a unique and independent opportunity to constrain the axial vector sector of the weak interaction, and it provides a discussion of alternative ways to determine the axial dipole mass in the quasielastic scattering region, a fundamental parameter that is in debate for nearly two decades. It also focuses on the study of the axial-vector form factors associated with the excitation of the $P_{33} (1232)$ resonance in a manner that is free from the uncertainties inherent in their determination from studies of (anti)neutrino-induced weak processes.
Comments:
Invited review article; 89 pages, 60 figures, and 13 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2607.13523 [pdf]
0 citations
08
[Submitted on 15 Jul 2026] (cross-list from nucl-ex)
Nuclear Charge Radius of $^{9}$ Be from Muonic Atom Spectroscopy Using a Microcalorimeter
Ofir Eizenberg🇮🇱 · Shikha Rathi🇮🇱 · Andreas Abeln🇩🇪 · Sonia Bacca🇩🇪 · Gonçalo Baptista🇫🇷 · Nir Barnea🇮🇱 · Noam Burger🇮🇱 · Thomas Elias Cocolios🇧🇪 · Marie Deseyn🇧🇪 · Tim Egert🇩🇪 · Christian Enss🇩🇪 · Andreas Fleischmann🇩🇪 and 25 other authors
The $2 p \to 1 s$ transition energy in muonic $^{9}$ Be was measured using a metallic magnetic calorimeter, resulting in $E_{2 p \to 1 s} = 33 391.48 (34)$ eV. The result is 30 times more precise than the previous best measurement and enables the extraction of the corresponding nuclear charge radius $r_{c} ($ $^{9}$ Be $) = 2.5506 (51)$ fm. It is $2.4$ times more precise than the commonly used value based on electron scattering and differs from it by $2.3$ times the combined uncertainties. This measurement represents the first determination of a nuclear charge radius using muonic x-ray spectroscopy with microcalorimeters.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2607.13690 [pdf]
2 citations
09
[Submitted on 15 Jul 2026] (cross-list from nucl-ex)
Evidence for sequential $Υ$ (nS) suppression in light ion collisions
CMS Collaboration
Bound states of heavy quark-antiquark pairs, known as quarkonia, have long been regarded as particularly sensitive probes of the quark-gluon plasma (QGP). Comparing quarkonium yields in collisions of heavy nuclei, such as gold or lead, with a proton-proton (pp) reference reveals a characteristic pattern of sequential suppression, in which weakly-bound excited states are more strongly suppressed than the ground states. We report the first measurements of the three lowest mass $S$ -wave vector bottomonium resonances, the ground state $Υ$ (1S) and the excited states $Υ$ (2S) and $Υ$ (3S), in oxygen-oxygen collisions at a center-of-mass energy per nucleon pair of $s_{NN}$ = 5.36 TeV. Measurements of the yields of the $Υ$ (1S) and $Υ$ (2S) resonances in neon-neon collisions, at the same $s_{NN}$ , are also presented. The $Υ$ (2S)/ $Υ$ (1S) ratio is found to be significantly below the measured pp reference value, and the $Υ$ (3S)/ $Υ$ (1S) ratio shows an even larger reduction. The significance of the relative $Υ$ (3S) to $Υ$ (2S) suppression exceeds three standard deviations. These results provide evidence for the sequential suppression of $Υ$ (nS) states in light ion collisions, similar to observations made in lead-lead and gold-gold collisions, generally attributed to the presence of a QGP medium.
Comments:
Submitted to Physical Review Letters. All figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/HIN-25-015 (CMS Public Pages)
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2607.13758 [pdf]
2 citations

Affiliations

first authorsco-authorsvia INSPIRE

Weak charged current induced electron and positron scattering off proton at JLab and MAMI energies

Nuclear Charge Radius of 9Be from Muonic Atom Spectroscopy Using a Microcalorimeter

Evidence for sequential Υ(nS) suppression in light ion collisions

Affiliations

Nuclear Charge Radius of $^{9}$ Be from Muonic Atom Spectroscopy Using a Microcalorimeter

Evidence for sequential $Υ$ (nS) suppression in light ion collisions