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Physical Review Letters
28 February 2003

Phys. Rev. Lett. 90, 081801 (2003)

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New Experimental Limit on the Photon Rest Mass with a Rotating Torsion Balance

Jun Luo, Liang-Cheng Tu, Zhong-Kun Hu, and En-Jie Luan

Department of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China

(Received 24 August 2002; published 26 February 2003)

A rotating torsion balance method is used to detect the product of the photon mass squared and the ambient cosmic vector potential A_e. The signal is modulated by rotating the torsion balance to ensure the effectiveness of detection for all possible orientations of the vector potential. The influences of sidereal disturbances of environment are also removed by virtue of this modulation method. The experimental result shows µA_e<1.1×10^–11   T m/m², with µ as the characteristic length associated with photon mass. If the ambient cosmic vector potential A_e is 10¹²   T m due to cluster level fields, we obtain a new upper limit on photon mass of 1.2×10^–51   g. ©2003 The American Physical Society

URL: http://link.aps.org/abstract/PRL/v90/e081801
doi:>10.1103/PhysRevLett.90.081801
PACS: 12.20.Fv, 14.70.Bh, 98.80.Cq        Additional Information>