Testing Brans-Dicke Gravity with Screening by Scalar Gravitational Wave
  Memory
  The Brans-Dicke theory of gravity is one of the oldest ideas to extend
general relativity by introducing a non-minimal coupling between the scalar
field and gravity. The Solar System tests put tight constraints on the theory.
In order to evade these constraints, various screening mechanisms have been
proposed. These screening mechanisms allow the scalar field to couple to matter
as strongly as gravity in low density environments while suppressing it in the
Solar System. The Vainshtein mechanism, which is found in various modified
gravity models such as massive gravity, braneworld models and scalar tensor
theories, suppresses the scalar field efficiently in the vicinity of a massive
object. This makes it difficult to test these theories from gravitational wave
observations. We point out that the recently found scalar gravitational wave
memory effect, which is caused by a permanent change in spacetime geometry due
to the collapse of a star to a back hole can be significantly enhanced in the
Brans-Dicke theory of gravity with the Vainshtein mechanism. This provides a
possibility to detect scalar gravitational waves by a network of three or more
gravitational wave detectors.
