Abstract
We revisit the "sequester" proposal of Kaloper, Padilla and collaborators, in which the amplitude of the cosmological constant is decoupled from large contributions due to loops containing Standard Model particles. We review the different formulations of the model that have appeared in the literature, and estimate the importance of a particular class of quantum corrections-those that dress the interaction between the "rigid" scalars and infrared properties of the spacetime such as its 4-volume and integrated curvature. In formulations that do not adequately sequester graviton loops we argue that dressing of these interactions causes further failures of complete sequestration. We estimate the size of the effect and find that it is typically smaller than the cosmological term directly induced by loops containing a single virtual graviton. Meanwhile, in the most developed formulation of the scenario (where a rigid scalar couples to the Gauss-Bonnet density), this dressing can be absorbed into a rescaling of the rigid fields and is therefore harmless.
Highlights
It is nearly 40 years since the cosmological constant problem was first stated clearly [1,2]. (For the earlier history, see Ref. [3,4].) Despite immense efforts over the intervening decades, it remains the most enigmatic component of the concordance cosmological model
Stability of global constraint.—we argue that detuning the dynamical equation for Λ can prevent complete sequestration
In this paper we have studied a class of radiative corrections to the sequester model proposed by Kaloper, Padilla and collaborators
Summary
It is nearly 40 years since the cosmological constant problem was first stated clearly [1,2]. (For the earlier history, see Ref. [3,4].) Despite immense efforts over the intervening decades, it remains the most enigmatic component of the concordance cosmological model. We should not be satisfied with a theory in which Λ is made technically natural at the expense of other lowenergy constants that receive large ultraviolet corrections If this occurs we have not removed the problem, but merely translated it from one low-energy sector to another. A global constraint couples the cosmological term to this conformal factor, allowing it to absorb contributions from pure matter loops In this version, loops involving virtual gravitons are known to reintroduce unsequestered corrections to the observed Λ. Loops involving virtual gravitons are known to reintroduce unsequestered corrections to the observed Λ We generally frame our calculations in Minkowski space to avoid unneeded complexities associated with curved spacetime; because ultraviolet properties do not depend on these curvature scales, this procedure does not forfeit any essential generality
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