Landscape, the Scale of SUSY Breaking, and Inflation

Department of Physics, Stanford University, Stanford, California, United States
Journal of High Energy Physics (Impact Factor: 6.11). 11/2004; 0412(12). DOI: 10.1088/1126-6708/2004/12/004
Source: arXiv


We argue that in the simplest version of the KKLT model, the maximal value of the Hubble constant during inflation cannot exceed the present value of the gravitino mass, H< m_{3/2}. This may have important implications for string cosmology and for the scale of the SUSY breaking in this model. If one wants to have inflation on high energy scale, one must develop phenomenological models with an extremely large gravitino mass. On the other hand, if one insists that the gravitino mass should be O(1 TeV), one will need to develop models with a very low scale of inflation. We show, however, that one can avoid these restrictions in a more general class of KKLT models based on the racetrack superpotential with more than one exponent. In this case one can combine a small gravitino mass and low scale of SUSY breaking with the high energy scale of inflation. Comment: 7 pages, 4 figs, revtex, typos corrected

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    • "In LVS models where H > m 3/2 m 3/2 M P and the inflaton is the volume mode, the destabilisation problem of [1] becomes an overshooting problem since the inflaton has an initial energy which is larger than the barrier to decompactification. The solution to this problem via radiation production after the end of inflation has already been discussed in [2], and so we shall not dwell on this issue. "
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    ABSTRACT: High-scale string inflationary models are in well-known tension with low-energy supersymmetry. A promising solution involves models where the inflaton is the volume of the extra dimensions so that the gravitino mass relaxes from large values during inflation to smaller values today. We describe a possible microscopic origin of the scalar potential of volume modulus inflation by exploiting non-perturbative effects, string loop and higher derivative perturbative corrections to the supergravity effective action together with contributions from anti-branes and charged hidden matter fields. We also analyse the relation between the size of the flux superpotential and the position of the late-time minimum and the inflection point around which inflation takes place. We perform a detailed study of the inflationary dynamics for a single modulus and a two moduli case where we also analyse the sensitivity of the cosmological observables on the choice of initial conditions.
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    • "For example, in the G2 − M SSM , the gravitino mass is comparable to the moduli mass and so the decay is kinetically forbidden [12]. Another challenging problem is the so-called 'over-shoot' or 'Kallosh-Linde' problem [49]. As an example, in Type IIB (KKLT) string compactifications, the height of the stabilization barrier is set by the gravitino mass. "
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    ABSTRACT: We critically review the role of cosmological moduli in determining the post-inflationary history of the universe. Moduli are ubiquitous in string and M-theory constructions of beyond the Standard Model physics, where they parametrize the geometry of the compactification manifold. For those with masses determined by supersymmetry breaking this leads to their eventual decay slightly before Big Bang Nucleosynthesis (without spoiling its predictions). This results in a matter dominated phase shortly after inflation ends, which can influence baryon and dark matter genesis, as well as observations of the Cosmic Microwave Background and the growth of large-scale structure. Given progress within fundamental theory, and guidance from dark matter and collider experiments, non-thermal histories have emerged as a robust and theoretically well-motivated alternative to a strictly thermal one. We review this approach to the early universe and discuss both the theoretical challenges and the observational implications.
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    • "Only that it would require the height of the inflaton potential to be much higher that the SUSY-breaking scalar potential. This may lead to problems e.g. in scenarios in which there are moduli whose vevs are fixed upon SUSY breaking, see e.g.[4]. "
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    ABSTRACT: Recent BICEP2 results on CMB polarisation B-modes suggest a high value for the inflation scale $V_0^{1/4} \simeq 10^{16}$ GeV, giving experimental evidence for a physical scale in between the EW scale and the Planck mass. We propose that this new high scale could be interpreted as evidence for a high SUSY breaking scale $M_{ss}\simeq 10^{12}-10^{13}$ GeV. We show that such a large value for $M_{ss}$ is consistent with a Higgs mass around 126 GeV. We briefly discuss some possible particle physics implications of this assumption.
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