Reference for how virtual particles gravitate?

Question

I was reading the slides from an interesting talk by Raphael Bousso. On slide 12 he wrote:

Virtual particles contribute different fractions of the mass of different materials (e.g., to the nuclear electrostatic energy of aluminum and platinum) I If they did not gravitate, we would have detected this difference in tests of the equivalence principle (in this example, to precision $10^6$)

I was wondering if there is a good reference which discusses this in more detail?

Answer 1

Bousso himself discusses it in his TASI lectures on the cosmological constant. See section 2.3 and references therein.