Who's Afraid of the Supersymmetric Dark? The Standard Model vs Low‐Energy Supergravity

Abstract

Use of supergravity equations in astronomy and late-universe cosmology is often criticized on three grounds: (i) phenomenological success usually depends on the supergravity form for the scalar potential applying at the relevant energies; (ii) the low-energy scalar potential is extremely sensitive to quantum effects involving very massive particles and so is rarely well-approximated by classical calculations of its form; and (iii) almost all Standard Model particles count as massive for these purposes and none of these are supersymmetric. Why should Standard Model loops preserve the low-energy supergravity form even if supersymmetry is valid at energies well above the electroweak scale? We use recently developed tools for coupling supergravity to non-supersymmetric matter to estimate the loop effects of heavy non-supersymmetric particles on the low-energy effective action, and provide evidence that the supergravity form is stable against integrating out such particles (and so argues against the above objection). This suggests an intrinsically supersymmetric picture of Nature where supersymmetry survives to low energies within the gravity sector but not the visible sector (for which supersymmetry is instead non-linearly realized). We explore the couplings of both sectors in this picture and find that the presence of auxiliary fields in the gravity sector makes the visible sector share many features usually attributed to linearly realized supersymmetry although (unlike for the MSSM) a second Higgs doublet is not required for all Yukawa couplings to be non-vanishing and changes the dimension of the operator generating the Higgs mass. We discuss the naturalness of this picture and some of the implications it might have when searching for dark-sector physics.

String Cosmology: from the Early Universe to Today

“…Progress on these questions may be facilitated by recently developed tools in coupling non-supersymmetric matter to supergravity [912,913,914,915,916,917]. This has been initiated in [918], where evidence was found that the supergravity form of the action -and a small splitting in the gravity supermultiplet -is stable against integrating out heavy, non-supersymmetric particles, thanks to the interplay with auxiliary fields associated with gravity, the goldstino and other supermultiplets in the supersymmetric gravity sector. Having a gravity sector that is supersymmetric down to low energies, coupled to a visible sector where supersymmetry is non-linearly realised, is also motivated by the fact that gravity would have the weakest couplings to any supersymmetry breaking sector [455].…”

Yoga Dark Energy: natural relaxation and other dark implications of a supersymmetric gravity sector

“…Crucially, their presence changes the way that UV physics can enter into the low-energy potential; because supersymmetry-breaking masses necessarily themselves involve F the contribution of virtual heavy nonsupersymmetric states to the lowenergy potential tends to be δV ∝ M 2 F +h.c. (where M is the UV scale) rather than directly as an F -independent term like δV ∝ M 4 [21]. Even though M 4 eventually arises once F is integrated out, the form involving F shows that the most UV-sensitive effective couplings have a reduced dimension.…”

“…Ref. [21] explores more concretely why generic potentials are consistent with the above supergravity form, using this general framework. When supersymmetry is nonlinearly realized (as it must be in such theories) there is always a low-energy superfield X that is nilpotent, X 2 = 0, since this is what is required to represent the goldstino [34], and it is typically true that W X = 0 for this field.…”

“…We here propose a class of models that we hope can provide such a point of comparison. These models are designed to address the low-energy 1 (and so hardest) part of the cosmological constant problem and are built on the interplay of three separate ingredients, all of which seem to play important roles: (i) A very supersymmetric gravity sector, for which supermultiplets are split by much less than for Standard Model fields (see [21] for a discussion of some other implications and the naturality of this assumption).…”

Loops, local corrections and warping in the LVS and other type IIB models

“…We consider it safer to include the loop effects as corrections to the Kahler potential, and then to study the minima of the resulting supergravity scalar potential. The validity of such an approach, even concerning loops with fields below the SUSY breaking scale, has recently been emphasized in [54].…”