Subatomic systems are pivotal for understanding fundamental baryonic interactions, as they provide direct access to quark-level degrees of freedom. In particular, the inclusion of a strange quark introduces strangeness as a new dimension, offering a powerful tool for exploring nuclear forces. The hypertriton, the lightest three-body hypernuclear system, provides an ideal testing ground for investigating baryonic interactions and quark behavior involving up, down, and strange quarks. However, experimental measurements of its lifetime and binding energy, key indicators of baryonic interactions, exhibit significant deviations in results obtained from energetic collisions of heavy-ion beams. Identifying alternative pathways for precisely measuring the hypertriton’s binding energy and lifetime is thus crucial for advancing experimental and theoretical nuclear physics. Herein, we present an experimental study on the binding energies of $^{3}_{\Lambda }\rm {H}$(hypertriton) and $^{4}_{\Lambda }\rm {H}$, performed through the analysis of photographic nuclear emulsions using state-of-the-art technologies. By incorporating deep-learning techniques, we uncovered systematic uncertainties in conventional nuclear emulsion analysis and established a refined calibration protocol for accurately determining binding energies. Our results are independent of those obtained from heavy-ion collision experiments, thereby offering a complementary measurement and opening new avenues for investigating few-body hypernuclei interactions.

Background: The evolution of shell structure around doubly magic exotic nuclei is of great interest in nuclear physics and astrophysics. In the ‘southwest’ region of ${}^{78}\mathrm{Ni}$, the development of deformation might trigger a major shift in our understanding of explosive nucleosynthesis. To this end, new spectroscopic information on key close-lying nuclei is very valuable.

The missing mass of the ^{12}C(p,d) reaction has been measured near the η^{'}-meson emission threshold in coincidence with a high-momentum proton to selectively collect η^{'}-^{11}C mesic nucleus formation events at GSI, Germany. A 2.5 GeV proton excites a carbon nucleus in order to form an η^{'}-mesic nucleus emitting a deuteron forward with an energy of ∼1.5 GeV. The deuteron is momentum analyzed by the fragment separator used as a high-resolution spectrometer to deduce the excitation energy of the residual system. The large-acceptance detector WASA surrounding the target identifies high-momentum protons emitted in the decay of the η^{'}-mesic nucleus. The measured semiexclusive spectrum exhibits structures below the threshold though the statistical significance is limited. The spectrum is fitted by theoretically calculated spectra varying optical-potential parameters of the η^{'}-nucleus interaction. The analysis results indicate possible formation of η^{'}-mesic nuclei for the real potential depth of ∼-61 MeV with a local statistical significance of 3.5σ and, taking into account the look-elsewhere effect, a global significance of 2.1σ.