52994021
The Muon (g-2) Theory Value: Present and Future
This White Paper briefly reviews the present status of the muon (g-2) Standard-Model prediction. This value results in a 3 - 4 standard-deviation difference with the experimental result from Brookhaven E821. The present experimental uncertainty is ±63×10−11 (0.54~ppm), and the Standard-Model uncertainty is ≃±49×10−11. Fermilab experiment E989 has the goal to reduce the experimental error to ±16×10−11. Improvements in the Standard-Model value, which should be achieved between now and when the first results from Fermilab E989 could be available, should lead to a Standard-Model uncertainty of ~±35×10−11. These improvements would halve the uncertainty on the difference between experiment and theory, and should clarify whether the current difference points toward New Physics, or to a statistical fluctuation. At present, the (g-2) result is arguably the most compelling indicator of physics beyond the Standard Model and, at the very least, it represents a major constraint for speculative new theories such as supersymmetry, dark gauge bosons or extra dimensions.
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.
118362394
Calculation of the parity-violating 5s-6s E1 amplitude in the rubidium atom
Currently, the theoretical uncertainty limits the interpretation of the atomic parity-nonconservation (PNC) measurements. We calculate the PNC 5s-6s electric dipole transition amplitude in rubidium and demonstrate that rubidium is a good candidate to search for new physics beyond the standard model since accuracy of the atomic calculations in rubidium can be higher than in cesium. PNC in cesium is currently the best low-energy test of the standard model; therefore, similar measurements for rubidium present a good option for further progress in the field. We also calculate the nuclear spin-dependent part of the PNC amplitude, which is needed for the extraction of the nuclear anapole moment from the PNC measurements. DOI:10.1103/PhysRevA.86.062512