α-Clustering in atomic nuclei from first principles with statistical learning and the Hoyle state character

Area of Science:

• Nuclear Physics
• Quantum Many-Body Systems
• Astroparticle Physics

Background:

• The existence of alpha clustering, where alpha particles (helium-4 nuclei) act as building blocks in atomic nuclei, has been a long-standing question.
• Alpha particles are exceptionally stable due to their high binding energy, making them plausible nuclear constituents.
• Despite theoretical plausibility, direct experimental evidence for alpha clustering has been lacking.

Purpose of the Study:

• To investigate the occurrence and mechanisms of alpha clustering in atomic nuclei.
• To provide direct experimental evidence for alpha particle emergence within nuclei.
• To explore the role of alpha clustering in nuclear structure and stability, particularly concerning the Hoyle state.

Main Methods:

• Employed state-of-the-art quantum many-body simulations from first principles.
• Utilized high-performance supercomputing resources, including the K/Fugaku supercomputer.
• Analyzed nuclear density profiles for beryllium-8, beryllium-10, and carbon-12.
• Incorporated statistical learning for additional insights.

Main Results:

• Demonstrated the emergence and variation of alpha clustering in atomic nuclei.
• Obtained physical quantities from simulations that align with experimental data.
• Visualized alpha clustering using density profiles for specific isotopes (Be-8, Be-10, C-12).
• Revealed an unexpected crossover picture for the Hoyle state, crucial for stellar nucleosynthesis.

Conclusions:

• The study presents compelling evidence for alpha clustering in atomic nuclei through advanced computational methods.
• The findings validate the hypothesis of alpha particles as nuclear building blocks and offer new insights into nuclear structure.
• The characterization of the Hoyle state's crossover behavior has significant implications for understanding the origin of elements and the birth of life in the universe.