Stars, like our own Sun, produce energy through nuclear fusion. In this process, two light atomic nuclei combine to form one or more heavier atomic nuclei and additional sub-atomic particles, such as neutrons.
A new study by a team of nuclear theorists from the University of Pisa, the Istituto Nazionale Fisica Nucleare in Italy, the Theory Center at the Thomas Jefferson National Accelerator Facility, and Washington University in St. Louis explores muon capture to gain valuable insights into stellar hydrogen burning.
Muons are subatomic particles that resemble electrons but are 207 times heavier. When a muon binds with a hydrogen isotope called a deuteron, it forms a system of two neutrons. This process is similar to proton-proton fusion, where two protons combine to create a deuteron.
The researchers used advanced models derived from chiral effective field theory to investigate the muon capture rate and describe the interaction among nucleons and their interactions with the muon. They identified four sources of theoretical uncertainty: model dependence, chiral-order convergence for the weak nuclear current, uncertainty in the single-nucleon axial form factor, and the numerical technique for solving bound and scattering systems.
The researchers found that the total theoretical uncertainty is approximately 2%, which is lower than experimental errors. This suggests that muon capture can be used to accurately study proton-proton fusion and other processes relevant to stellar hydrogen burning.
The study’s findings support ongoing efforts to enhance the accuracy of muon capture measurements. The researchers also plan to include muon capture processes on helium-3 and lithium-6 in their future work and to apply the same theoretical framework to investigate other weak processes relevant to solar standard models and neutrino fluxes.
The study by Ceccarelli and her colleagues could have a significant impact on our understanding of stellar hydrogen burning and other processes in the Sun and other stars. The ability to accurately model these processes could help scientists to better understand the evolution of stars and the origins of the elements.
The study could also have implications for the development of new energy sources. For example, muon capture could be used to develop a new type of fusion reactor that is more efficient and safer than existing designs.