Precision Measurements in Intermediate Energy Physics

Trustees Of Boston University, Boston

Investigators

Abstract

This project covers several precision measurements in particle physics. Precision measurements complement measurements at the highest energies, providing important constraints on the interpretation of data from the highest energies. The measurement of the muon lifetime, which gives the parameter G-Fermi and determines the strength of the weak force, will provide an improvement of this fundamental parameter by a factor of twenty better than it is presently known. This value will help constrain other parameters of the standard model of nuclear and particle physics. Our search for a permanent electric dipole moment of the neutron could obtain evidence for a new source of the violation of charge-parity (CP) symmetries, which at present has only been observed in the neutral K-meson and B-meson systems. While the asymmetry in the universe between matter (which we are made of) and antimatter could be partially explained by CP violation, the known source of CP violation is inadequate to explain the dominance of matter over antimatter. Finally, we are exploring the possibility of continuing our measurement of the magnetic moment of the muon, which is like a heavy electron. Our measurements at the Brookhaven National Laboratory obtained a value that is larger than that predicted by the standard model by 3.4 standard deviations, which indicates a 99% probability that this result cannot be explained by the standard model. We know that the standard model is incomplete, and many speculative extensions to it have predicted an effect consistent with our measurements. These projects provide significant educational and training opportunities for postdoctoral research associates and graduate students, as well as important roles in carrying out the research efforts.