TY - JOUR

T1 - Collective Scalarization or Tachyonization

T2 - When Averaging Fails

AU - Cardoso, Vitor

AU - Foschi, Arianna

AU - Zilhao, Miguel

PY - 2020/6/5

Y1 - 2020/6/5

N2 - Certain scalar-tensor theories of gravity provide negative-energy, tachyonic modes to a fundamental scalar inside matter, giving rise to nonperturbative phenomena around compact stars. Studies of this and other tachyonic instabilities always average over local matter properties. We use elementary, flat space models to understand possible collective effects and the accuracy of the averaging procedure. In particular, we consider bodies made of elementary constituents which do not, in isolation, scalarize because their compactness C is too small, C less than or similar to C-crit. We show that when the individual constituents have compactness smaller but close to the threshold, one is able to scalarize composite bodies through collective effects, and the compactness of the composite body can be made arbitrarily small. On the other hand, our results suggest that when the fundamental building blocks have very low compactness, then scalarization of the composite body requires a global compactness C-global greater than or similar to C-crit. Thus, our results rule out scalarization of dilute bodies via collective effects.

AB - Certain scalar-tensor theories of gravity provide negative-energy, tachyonic modes to a fundamental scalar inside matter, giving rise to nonperturbative phenomena around compact stars. Studies of this and other tachyonic instabilities always average over local matter properties. We use elementary, flat space models to understand possible collective effects and the accuracy of the averaging procedure. In particular, we consider bodies made of elementary constituents which do not, in isolation, scalarize because their compactness C is too small, C less than or similar to C-crit. We show that when the individual constituents have compactness smaller but close to the threshold, one is able to scalarize composite bodies through collective effects, and the compactness of the composite body can be made arbitrarily small. On the other hand, our results suggest that when the fundamental building blocks have very low compactness, then scalarization of the composite body requires a global compactness C-global greater than or similar to C-crit. Thus, our results rule out scalarization of dilute bodies via collective effects.

KW - POTENTIAL WELLS

KW - SCALAR THEORIES

U2 - 10.1103/PhysRevLett.124.221104

DO - 10.1103/PhysRevLett.124.221104

M3 - Letter

VL - 124

JO - Physical Review Letters

JF - Physical Review Letters

SN - 0031-9007

IS - 22

M1 - 221104

ER -