Microscopic realization of the Cohen–Kaplan–Nelson (CKN) UV/IR bound

Establish a microscopic realization of the Cohen–Kaplan–Nelson UV/IR mixing bound Λ_UV^d ≤ M_Pl,d^{d−2} Λ_IR^2 in anti–de Sitter spacetime directly from the ten- or eleven-dimensional supergravity equations of motion, identifying the specific dynamical ingredient(s)—distinct from BPS domain walls—that enforce this inequality in the low-energy effective description.

Background

The paper derives a domain wall bound Λ_UV^{d−1} ≤ M_Pl,d^{d−2} L_AdS^{-1} from ten-dimensional string theory, relating UV/IR mixing in AdS to the existence of fundamental flux-changing domain walls. This reproduces, with Λ_IR identified as 1/L_AdS, the covariant entropy bound and implies lower bounds on the gravitino mass.

The authors contrast this with the stronger CKN bound Λ_UV^d ≤ M_Pl,d^{d−2} Λ_IR^2, which is motivated by requiring that a weakly interacting system not collapse into a black hole. While they can encode their domain wall bound in supergravity, they do not identify a corresponding microscopic mechanism for the CKN inequality, leaving its derivation from fundamental equations as an open problem.