β-Nuclear-Recoil Correlation from ^{6}He Decay in a Laser Trap

Area of Science:

• Nuclear Physics
• Particle Physics
• Atomic Physics

Background:

• The Standard Model of particle physics describes fundamental forces, but searches for physics beyond it are ongoing.
• Exotic tensor contributions to the weak interaction could indicate new physics, such as right-handed neutrinos.

Purpose of the Study:

• To perform the first precise measurement of beta-recoil correlation in radioactive 6He.
• To search for evidence of exotic tensor-type contributions to the charged weak current.
• To set limits on the ratio of tensor to axial-vector coupling constants (CT/CA).

Main Methods:

• Radioactive 6He atoms were confined using a magneto-optical trap.
• Beta-recoil correlations were precisely measured.
• Experimental uncertainties in time response and detector distance were analyzed.

Main Results:

• The measurement yielded |CT/CA|^2 ≤ 0.022 (90% C.L.) for right-handed neutrinos.
• For left-handed neutrinos, the limits found were 0.007 < CT/CA < 0.111 (90% C.L.).
• Experimental uncertainties were identified as the main limitation to measurement sensitivity.

Conclusions:

• The study provides stringent limits on tensor currents in beta decay.
• The results constrain theories with exotic tensor interactions and right-handed neutrinos.
• Improved experimental techniques are needed to further enhance sensitivity.