Confinement in Nuclei and the Expanding Proton

Area of Science:

• Nuclear Physics
• Atomic Physics
• Quantum Chromodynamics

Background:

• High-precision electromagnetic form factors are crucial in nuclear and atomic physics.
• The non-zero spatial extent of nucleons must be carefully considered for precise calculations.

Purpose of the Study:

• To investigate the effects of nucleon spatial extent on electromagnetic form factors.
• To develop models that accurately describe composite proton structure and quark confinement.

Main Methods:

• Utilized a series of simple, Poincaré-invariant, composite-proton models.
• Ensured models respect the Ward-Takahashi identity for theoretical consistency.
• Integrated findings with lattice Quantum Chromodynamics (QCD) calculations.

Main Results:

• Demonstrated a general theorem explaining medium modification of proton structure.
• Showcased how composite models reveal essential aspects of nucleon structure.
• Quantified the impact of binding on proton size.

Conclusions:

• A bound proton is concluded to be larger than a free proton.
• The study provides a theoretical framework for understanding in-medium nucleon properties.
• Results have implications for high-precision nuclear and atomic physics experiments.