We investigate the dynamical breaking of local supersymmetry (supergravity), including the Deser-Zumino super-Higgs effect, via the corresponding one-loop effective potential for the simple but quite representative cases of N = 1, D = 4 simple supergravity and a (simplified) conformal version of it. We find solutions to the effective equations which indicate dynamical generation of a gravitino mass, thus breaking supergravity. In the case of conformal supergravity models, the gravitino mass can be much lower than the Planck scale, for global supersymmetry breaking scales below the Grand Unification scale. The absence of instabilities in the effective potential arising from the quantum fluctuations of the metric field is emphasised, contrary to previous claims in the literature.arXiv:1310.4122v1 [hep-th]

Gravitino-condensate-induced inflation via the super-Higgs effect is a UV-motivated scenario for both inflating the early universe and breaking local supersymmetry dynamically, entirely independent of any coupling to external matter. As an added benefit, this also removes the (as of yet unobserved) massless Goldstino associated to global supersymmetry breaking from the particle spectrum. In this review, we detail the pertinent properties and outline previously hidden details of the various steps required in this context in order to make contact with current inflationary phenomenology. The class of models of SUGRA we use to exemplify our approach are minimal four-dimensional N = 1 supergravity and extensions thereof with broken conformal symmetry. Therein, the gravitino condensate itself can play the role of the inflation, however the requirement of slow-roll necessitates unnaturally large values of the wave function renormalization. Nevertheless, there is an alternative scenario that may provide Starobinsky-type inflation, occurring in the broken-SUGRA phase around the nontrivial minima of the gravitino-condensate effective potential. In this scenario higher curvature corrections to the effective action, crucial for the onset of an inflationary phase, arise as a result of integrating out massive quantum gravitino fields in the path integral. The latter scenario is compatible with Planck satellite phenomenology but not with BICEP2 data.

In the context of dynamical breaking of local supersymmetry (supergravity), including the DeserZumino super-Higgs effect, for the simple but quite representative cases of N = 1, D = 4 supergravity, we discuss the emergence of Starobinsky-type inflation, due to quantum corrections in the effective action arising from integrating out gravitino fields in their massive phase. This type of inflation may occur after a first-stage small-field inflation that characterises models near the origin of the one-loop effective potential, and it may occur at the non-trivial minima of the latter. Phenomenologically realistic scenarios, compatible with the Planck data, may be expected for the conformal supergravity variants of the basic model. This short article serves as an addendum to our previous publication [1], where we discussed dynamical breaking of supergravity (SUGRA) theories via gravitino condensation. In particular, we shall demonstrate the compatibility of this scenario with Starobinsky-like [2] inflationary scenarios, which in our case can characterise the massive gravitino phase. As we shall argue, this is a second inflationary phase, that may succeed a first inflation which occurs in the flat region of the one-loop effective potential for the gravitino condensate field [3].Starobinsky inflation is a model for obtaining a de Sitter (inflationary) cosmological solution to gravitational equations arising from a (four space-time-dimensional) action that includes higher curvature terms, specifically of the type in which the quadratic curvature corrections consist only of scalar curvature terms [2]where κ 2 = 8πG, and G = 1/m 2 P is Newton's (gravitational) constant in four space-time dimensions, with m P the Planck mass, and M is a constant of mass dimension one, characteristic of the model.The important feature of this model is that inflationary dynamics are driven by the purely gravitational sector, through the R 2 terms, and the scale of inflation is linked to M. From a microscopic point of view, the scalar curvature-squared terms in (1) are viewed as the result of quantum fluctuations (at one-loop level) of conformal (massless or high energy) matter fields of various spins, which have been integrated out in the relevant path integral in a curved background space-time [4]. The quantum mechanics of this model, by means of tunneling of the Universe from a state of "nothing" to the inflationary phase of ref. [2] has been discussed in detail in [5]. The above considerations necessitate truncation to one-loop quantum order and to curvature-square (four-derivative) terms, which implies that there must be a region of validity for curvature invariants such that O R 2 /m 4 p 1, which is a condition satisfied in phenomenologically realistic scenarios of inflation [6,7], for which the inflationary Hubble scale H I ≤ 0.74 × 10 −5 m P = O(10 15 ) GeV (the reader should recall that R ∝ H 2 I in the inflationary phase).Although the inflation in this model is not driven by fundamental rolling scalar fields, nevertheless the model (...

The EDGES Collaboration has reported an anomalously strong 21 cm absorption feature corresponding to the era of first star formation, which may indirectly betray the influence of dark matter during this epoch. We demonstrate that, by virtue of the ability to mediate cooling processes while in the condensed phase, a small amount of axion dark matter can explain these observations within the context of standard models of axions and axionlike particles. The EDGES best-fit result favors an axionlike particle mass in the (10, 450) meV range, which can be compressed for the QCD axion to (100, 450) meV in the absence of fine tuning. Future experiments and large scale surveys, particularly the International Axion Observatory (IAXO) and EUCLID, should have the capability to directly test this scenario.

No abstract

No abstract

We identify a previously untapped discovery channel for grand-unification monopoles, arising from their ability to catalyse the direct decay of protons into monoenergetic 459 MeV antineutrinos within the Sun. Previous analyses omit this possibility as it necessarily involves an electroweak suppression factor, and instead search for the unsuppressed 20-50 MeV neutrinos produced via two-stage proton decays. By accounting for the relative difference in interaction cross section and experimental background at typical neutrino detection experiments, we demonstrate that this new channel in fact possesses greater discovery potential. As a case in point, using 5326 live days of Super-Kamiokande exposure we find that 2 σ (3 σ) deviations in the 20-50 MeV channel are amplified to 3 σ (4.6 σ) deviations in the 459 MeV case. Exploiting correlations between these two channels may also offer even greater statistical power.

The EDGES collaboration’s observation of an anomalously strong 21 cm absorption feature around the cosmic dawn era has energised the cosmological community by suggesting a novel signature of dark matter in the cooling of cosmic hydrogen. In a recent paper, we have argued that by virtue of the ability to mediate cooling processes whilst in the condensed phase, a small amount of axion dark matter can explain these observations within the context of Standard Models of axions and axion-like particles. These axions and axion-like particles (ALPs) can thermalise through gravitational self-interactions and so eventually form a Bose–Einstein condensate (BEC), whereupon large-scale long-range correlation can produce experimentally observable signals such as these. In this context, the EDGES best-fit result favours an ALP mass in the (6, 400) meV range. Future experiments and galaxy surveys, particularly the International Axion Observatory (IAXO) and EUCLID, should have the capability to directly test this scenario. In this paper, we will explore this mechanism in detail and give more thorough computational details of certain key points.