A New Approach for Measuring the Muon Anomalous Magnetic Moment and Electric Dipole Moment

Abstract

This paper introduces a new approach to measure the muon magnetic moment anomaly a µ = (g − 2)/2, and the muon electric dipole moment (EDM) d µ at the J-PARC muon facility. The goal of our experiment is to measure a µ and d µ using an independent method with a factor of 10 lower muon momentum, and a factor of 20 smaller diameter storage-ring solenoid compared with previous and ongoing muon g − 2 experiments with unprecedented quality of the storage magnetic field. Additional significant differences from the present experimental method include a factor of 1,000 smaller transverse emittance of the muon beam (reaccelerated thermal muon beam), its efficient vertical injection into the solenoid, and tracking each decay positron from muon decay to obtain its momentum vector. The precision goal for a µ is statistical uncertainty of 450 part per billion (ppb), similar to the present experimental uncertainty, and a systematic uncertainty less than 70 ppb. The goal for EDM is a sensitivity of 1.5 × 10 −21 e • cm.

Short-distance constraints for the longitudinal component of the hadronic light-by-light amplitude: an update

“…The recent measurement of (g − 2) µ by the Fermilab Muon g − 2 collaboration [1][2][3][4] has made the discrepancy with the Standard-Model prediction more serious, by bringing it from the 3.7σ to the 4.2σ level when combined with the previous Brookhaven measurement [30]. The concrete perspective of additional reductions of the experimental uncertainty in the near future-mainly from subsequent Runs at Fermilab [31], but also the future J-PARC experiment [32] using a different technique-makes the need of further theoretical improvements more urgent. As is well known, the two main sources of theoretical uncertainties are both hadronic.…”

Test of analyticity and unitarity for the pion form-factor data around the $ρ$ resonance

“…We recall that O(t) is an Omnès function, where φ(t) is equal to δ 1 1 (t) for t ≤ t in and is an arbitrary function above t in . The function denoted as ω(t) is analytic in the t plane cut for t > t in and has the modulus equal to |O(t)| on the cut, and w(z) is an outer function (analytic and without zeros in the unit disk |z| < 1), with modulus on the boundary |z| = 1 of the disk related to to the weight in the integral (3).…”

“…There is at present a disagreement between the experimental value of the muon anomaly measured at BNL [1] and its evaluation in the Standard Model (SM). Two new experiments aim at reducing the experimental uncertainty by a factor of four: the E989 experiment at Fermilab [2], which started running in 2018, and the E34 experiment at J-PARC, which plans to start its first run in 2024 [3]. In parallel, there is a continuous effort for improving the accuracy of the theoretical calculation of a µ in the SM (for a recent review and earlier references see [4]).…”

Charged Lepton EDM with Extra Yukawa Couplings

“…( 3). The Fermilab Muon g-2 [16] and the J-PARC muon g-2/EDM [17] experiments project sensitivities at ∼ 10 −21 e cm. Another experiment being planned at PSI [18] aims at improving by at least another order of magnitude, eventually reaching a sensitivity of 6 × 10 −23 e cm.…”