Nuclear physicists have made a significant breakthrough in understanding the mass distribution within subatomic particles, specifically pions and protons, through advanced numerical calculations that leverage the trace anomaly in spacetime.
The research focuses on exploring how mass is distributed within these fundamental particles, which are composed of quarks and held together by the strong nuclear force. By analyzing the trace anomaly—a complex quantum mechanical phenomenon that reveals how physical measurements change across different energy and momentum scales—scientists can gain unprecedented insights into the inner structure of subatomic particles.
The study revealed fascinating similarities and differences in mass distributions. For pions, which are composed of one quark and one antiquark, the mass distribution closely resembles the charge distribution of neutrons. In nucleons like protons and neutrons, the mass distribution aligns more closely with the charge distribution of protons.
These calculations are particularly significant in the context of future experiments at the Electron-Ion Collider (EIC) at Brookhaven National Laboratory. The EIC’s primary scientific goals include understanding the origin of nucleon mass and exploring how mass from quarks and gluons is distributed within hadrons. By using first-principle numerical calculations, scientists can now predict and interpret complex subatomic interactions with greater precision.
The methodology employed in this research is groundbreaking. Starting from fundamental physical laws, researchers developed numerical techniques that can extract detailed information about particle structure. This approach is analogous to how X-ray diffraction revealed the double-helix structure of DNA, providing a new lens through which to view subatomic particle composition.
Future electron-proton scattering experiments at the EIC will further validate these theoretical calculations. By producing heavy states sensitive to the proton’s inner structure, particularly gluon distributions, scientists can empirically test and refine their understanding of how mass is generated and distributed at the quantum scale.
These findings have broader implications for our understanding of the Standard Model of particle physics. They illuminate how absolute scales emerge and how left-handed and right-handed quantities interact at the most fundamental levels of matter.
The research represents a significant step forward in theoretical nuclear physics, offering a more nuanced view of the intricate mechanisms that govern the mass and structure of subatomic particles.
References:
“Trace anomaly form factors from lattice QCD” by χQCD Collaboration, Bigeng Wang, Fangcheng He, Gen Wang, Terrence Draper, Jian Liang, Keh-Fei Liu and Yi-Bo Yang, 9 May 2024, Physical Review D. DOI: 10.1103/PhysRevD.109.094504
“Hadrons, superconductor vortices, and cosmological constant” by Keh-Fei Liu, 27 December 2023, Physics Letters B. DOI: 10.1016/j.physletb.2023.138418
