Gravitational Friedel oscillations in higher-derivative and infinite-derivative gravity?

When a positively charged impurity is placed inside a cold metal, the resulting charge density around that object exhibits characteristic ripples to negative values, known as Friedel oscillations. In this essay, we describe a somewhat analogous effect in (i) linearized higher-derivative gravity and (ii) linearized infinite-derivative “ghost-free” gravity: when a gravitational impurity (point particle) is placed in Minkowski vacuum, the local energy density [Formula: see text] (with [Formula: see text]) exhibits oscillations to negative values. The wavelength of these oscillations is roughly given by (i) the Pauli–Villars regularization scale and (ii) the scale of nonlocality. We hence dub this phenomena gravitational Friedel oscillations.

Coordination-resolved bonding and electronic dynamics of Na atomic clusters and solid skins

Atomic undercoordination shortens the interatomic bond, deepens the energy level, raises the local energy density and lowers the atomic cohesive energy of Na solid skins and clusters.

PAIRING CORRELATIONS AND EFFECTIVE MASSES IN NUCLEI WITH LARGE NEUTRON EXCESS

We propose a local energy density functional for global description of pairing correlations by focusing on the neutron excess dependence. We show the clear correlation between pairing gaps and effective mass parameters as a function of neutron excess. This effect can be taken into account to the density functional by the isovector density dependence in the particle-particle channel.