Preferred-frame and CP-violation tests with polarized electrons
- Center for Experimental Nuclear Physics and Astrophysics, Box 354290, University of Washington, Seattle, Washington 98195-4290 (United States)
We used a torsion pendulum containing {approx_equal}10{sup 23} polarized electrons to search new interactions that couple to electron spin. We limit CP-violating interactions between the pendulum's electrons and unpolarized matter in the Earth or the Sun, test for rotation and boost-dependent preferred-frame effects using the Earth's rotation and velocity with respect to the entire cosmos, and search for exotic velocity-dependent potentials between polarized electrons and unpolarized matter in the Sun and Moon. We find CP-violating parameters |g{sub P}{sup e}g{sub S}{sup N}|/(({Dirac_h}/2{pi})c)<9.4x10{sup -37} and |g{sub A}{sup e}g{sub V}{sup N}|/(({Dirac_h}/2{pi})c)<1.2x10{sup -56} for {lambda}>1 AU. We test for preferred-frame interactions of the form V=-{sigma}{sup e}{center_dot}A, V=-B{sigma}{sup e}{center_dot}v/c, or , where v is the velocity of the Earth with respect to the cosmic microwave background restframe and i, j represent the equatorial inertial coordinates X, Y, and Z. We constrain all 3 components of A, obtaining 1{sigma} upper limits |A{sub X,Y}|{<=}1.5x10{sup -22} eV and |A{sub Z}|{<=}4.4x10{sup -21} eV that may be compared to the benchmark value m{sub e}{sup 2}/M{sub Planck}=2x10{sup -17} eV. Interpreting our constraint on A in terms of noncommutative geometry, we obtain an upper bound of (355l{sub GUT}){sup 2} on the minimum observable area, where l{sub GUT}=({Dirac_h}/2{pi})c/(10{sup 16} GeV) is the grand unification length. We find that |B|{<=}1.2x10{sup -19} eV. All 9 components of C are constrained at the 10{sup -17} to 10{sup -18} eV level. We determine 9 linear combinations of parameters of the standard model extension; rotational-noninvariant and boost-noninvariant terms are limited at roughly the 10{sup -31} GeV and 10{sup -27} GeV levels, respectively. Finally, we find that the gravitational mass of an electron spinning toward the galactic center differs by less than about 1 part in 10{sup 21} from an electron spinning in the opposite direction. As a byproduct of this work, the density of polarized electrons in Sm Co{sub 5} was measured to be (4.19{+-}0.19)x10{sup 22} cm{sup -3} at a field of 9.6 kG.
- OSTI ID:
- 21254594
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 78, Issue 9; Other Information: DOI: 10.1103/PhysRevD.78.092006; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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