122584301
The Fermilab muon (g−2) project
A proposal to Fermilab, P989, has the goal to improve on the precision of the muon anomalous magnetic moment, a μ = ( g μ − 2 ) / 2 by at least a factor of 4 beyond the 0.54 ppm relative precision obtained in E821 at Brookhaven. The precision storage ring will be moved to Fermilab and installed in a new building. A new 8 GeV/c proton beamline and 3.1 GeV/c muon beamline will be built. The unique capabilities of Fermilab to produce a proton beam with pulses containing ≃ 1 × 10 12 protons at an advantageous duty factor will provide the necessary increase of statistics in a reasonable running time. This new experiment should clarify the apparent difference between the experimental and Standard-Model values of a μ .
16376986
The Next-generation Muon (g-2) Experiment
The muon (g − 2) experiment at the Brookhaven AGS achieved a relative precision on the muon anomalous magnetic moment, a μ , of ±0.54 ppm. The anomaly is sensitive to a wide range of physics beyond the standard model such as supersymmetry, and thus can help constrain the interpretation of any " new physics " found at the Large Hadron Collider. It is desirable to improve the precision of the experiment and of the theoretical (standard-model) value. A new experiment to improve the precision of a μ to ±0.14 ppm is being discussed for Fermilab or J-PARC. The existing precision muon storage ring would be moved to one of these facilities. In parallel, a significant worldwide effort to improve the uncertainty on the standard model value is underway, and over the next several years could produce a significant improvement in the theory uncertainty. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
52994365
Strongly enhanced atomic parity violation due to close levels of opposite parity
We present calculations of nuclear-spin-dependent and nuclear-spin-independent parity-violating amplitudes in Ba, Ra,Ac+, Th, and Pa. Parity nonconservation in these systems is greatly enhanced due to the presence of very close electronic energy levels of opposite parity, large nuclear charge, and strong nuclear enhancement of parity-violating effects. The presented amplitudes constitute several of the largest atomic parity-violating signals predicted so far. Experiments using these systems may be performed to determine values for the nuclear anapole moment, a P-odd T -even nuclear moment given rise to by parity-violating nuclear forces. Such measurements may prove to be valuable tools in the study of parity violation in the hadron sector. The considered spin-independent transitions could also be used to measure the ratio of weak charges for different isotopes of the same atom, the results of which would serve as a test of the standard model and also of neutron distributions. Barium, with seven stable isotopes, is particularly promising in this regard.