arXiv subjects

T. S. Cook

Publications and source records attributed to T. S. Cook.

4 recordsLinked to original sources

arXiv2020

New Test of the Gravitational $1/r^2$ Law at Separations down to 52 $μ$m

We tested the gravitational $1/r^2$ law using a stationary torsion-balance detector and a rotating attractor containing test bodies with both 18-fold and 120-fold azimuthal symmetries that simultaneously tests the $1/r^2$ law at two different length scales. We took data at detector-attractor separations between $52~μ$m and 3.0 mm. Newtonian gravity gave an excellent fit to our data, limiting with 95\% confidence any gravitational-strength Yukawa interactions to ranges $< 38.6~μ$m.

hep-ex↗

arXiv2008

Preferred-Frame and CP-Violation Tests with Polarized Electrons

We used a torsion pendulum containing $\approx 10^{23}$ 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. Finally, we find that the gravitational mass of an electron spinning toward the galactic center differs by less than about 1 part in $10^{21}$ from an electron spinning in the opposite direction. As a byproduct of this work, the density of polarized electrons in Sm$ $Co$_5$ was measured to be $(4.19\pm 0.19)\times 10^{22} {\rm cm}^{-3}$ at a field of 9.6 kG.

hep-ex↗

arXiv2006

Tests of the Gravitational Inverse-Square Law below the Dark-Energy Length Scale

We conducted three torsion-balance experiments to test the gravitational inverse-square law at separations between 9.53 mm and 55 micrometers, probing distances less than the dark-energy length scale $λ_{\rm d}=\sqrt[4]{\hbar c/ρ_{\rm d}}\approx 85 μ$m. We find with 95% confidence that the inverse-square law holds ($|α| \leq 1$) down to a length scale $λ= 56 μ$m and that an extra dimension must have a size $R \leq 44 μ$m.

hep-ph↗

arXiv2006

New CP-violation and preferred-frame tests with polarized electrons

We used a torsion pendulum containing $\sim 9 \times 10^{22}$ polarized electrons to search for CP-violating interactions between the pendulum's electrons and unpolarized matter in the laboratory's surroundings or the sun, and to test for preferred-frame effects that would precess the electrons about a direction fixed in inertial space. We find $|g_{\rm P}^e g_{\rm S}^N|/(\hbar c)< 1.7 \times 10^{-36}$ and $|g_{\rm A}^e g_{\rm V}^N|/(\hbar c) < 4.8 \times 10^{-56}$ for $λ> 1$AU. Our preferred-frame constraints, interpreted in the Kostelecký framework, set an upper limit on the parameter $|\bm{\tilde {b}}^e| \leq 5.0 \times 10^{-21}$ eV that should be compared to the benchmark value $m_e^2/M_{\rm Planck}= 2 \times 10^{-17}$ eV.

hep-ph↗