Search for a proposed signature of Lorentz-invariant spacetime granularity

Abstract

We used a rotating torsion pendulum containing ≈1023 polarized electrons placed in an orientable quadrupole source to constrain Bonder and Sudarsky's quantum-gravity effect based on a Lorentz-invariant spacetime granularity model proposed by Corichi and Sudarsky. Our null results constrain the model's free parameters 13 orders of magnitude more tightly than those Bonder and Sudarsky obtained by reinterpreting the data from a previous polarized neutron experiment that was designed to test Lorentz invariance.

Experimental search for a Lorentz invariant spacetime granularity: Possibilities and bounds

“…The detection of the torque (45) would be the experimental signal arising from the proposed model. However, the Eöt-Wash group detected no torque [44] leading to the following bounds,…”

“…Note that we can write the total energy of the torsion pendulum as E e = −Nn · w, for a vector w that can be read off from equation (44). Thus, the torque exerted on the torsion pendulum is T = Nn × w, implying that its z component satisfies…”

A microscopic model for an emergent cosmological constant

“…This indicates that the present accelerated expansion of the universe might simply be the result of a noisy diffusion of energy into the underlying granularity of spacetime. 7 Massive gauge bosons do not change the order of magnitude estimate, as m Z /m t ≈ 1/2 and g ZW ± /g tt = 3/4. In (8) this leads to a factor (3/4) 2 (1/2) 4 which is about only 3.5% of the top-quark contribution.…”

Lorentz violation in a uniform Newtonian gravitational field

“…To first order in m 5 and the SME coefficients, the nonrelativistic Hamiltonian H FW is composed of the Lorentzinvariant Hamiltonian ( 14) plus the corrections given in Eqs. ( 18)- (32). Observe that each SME coefficient couples with spin and gravity in a particular way, and, in principle, every term in these expressions can be used to look for the coefficients' effects.…”