After decades of catching brief glimpses of a fleeting subatomic particle called the sigma in experimental data, nuclear physicists have used supercomputers to calculate it, with the result displaying similar properties to that of a real-world sigma particle inferred from experimental data.
Protons and neutrons are bound together into nuclei by the act of exchanging other subatomic particles, such as the sigma. The calculation of the sigma and its properties provides insight into the force that binds protons and neutrons together and demonstrates the feasibility of applying this method to the study of similarly elusive, short-lived particles.
Much like two friendly neighbors getting together to chat over a cup of coffee, the minuscule particles in our subatomic world also come together to engage in a kind of conversation. Nuclear scientists are developing tools to allow them to eavesdrop on the communication between subatomic particles, such as the protons and neutrons that build our visible universe, to better understand the force that binds these particles together. For instance, protons and neutrons are bound inside the nucleus by the strong force acting through the exchange of subatomic particles, such as the sigma. Scientists used supercomputers to perform the first calculation of the sigma particle directly from the theory called Quantum Chromodynamics, which is the theory that describes the strong force, the particles that interact through this force, and the nature of those interactions. This accomplishment paves the way for a better understanding of the strong force and its role in building our visible universe, and it opens the door for calculations of other short-lived subatomic particles.
Jefferson Lab and College of William & Mary
Jefferson Lab is supported by the Office of Science of the U.S. Department of Energy (DOE). This research used the resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the DOE Office of Science under contract DE-AC05-00OR22725. This research is part of the Blue Waters sustained-petascale computing project, which is supported by the National Science Foundation and the state of Illinois. This research also used resources at the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science user facility at DOE's Lawrence Berkeley National Laboratory. This research used resources at the Continuous Electron Beam Accelerator Facility, a DOE Office of Science user facility at Jefferson Lab. The authors acknowledge the Texas Advanced Computing Center (TACC) at the University of Texas at Austin for providing computing resources.
R.A. Bricen?o, J.J. Dudek, R.G. Edwards, and D.J. Wilson (for the Hadron Spectrum Collaboration), "Isoscalar ?? scattering and the ? meson resonance from QCD." Physical Review Letters 118, 022002 (2017). [DOI: 10.1103/PhysRevLett.118.022002]
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