arXiv subjects
Publications and source records attributed to C. Froggatt.
We argue that the exact degeneracy of vacua in N=1 supergravity can shed light on the smallness of the cosmological constant. The presence of such vacua, which are degenerate to very high accuracy, may also result in small values of the quartic Higgs coupling and its beta function at the Planck scale in the phase in which we live.
In N=1 supergravity supersymmetric (SUSY) and non-supersymmetric Minkowski vacua originating in the hidden sector can be degenerate. In the supersymmetric phase in flat Minkowski space non-perturbative supersymmetry breakdown may take place in the observable sector, inducing a non-zero and positive vacuum energy density. Assuming that such a supersymmetric phase and the phase in which we live are degenerate, we estimate the value of the cosmological constant. We argue that the observed value of the dark energy density can be reproduced in the Split-SUSY scenario of the supersymmetry breaking if the SUSY breaking scale is of order of 10^{10} GeV.
It is well known that global symmetries protect local supersymmetry and a zero value for the cosmological constant in no--scale supergravity. The breakdown of these symmetries, which ensure the vanishing of the vacuum energy density, results in a set of degenerate vacua with broken and unbroken supersymmetry leading to the natural realisation of the multiple point principle (MPP). Assuming the degeneracy of vacua with broken and unbroken SUSY in the hidden sector we estimate the value of the cosmological constant. We argue that the observed value of the dark energy density can be reproduced in the split-SUSY scenario if the SUSY breaking scale is of the order of 10^{10} GeV.
In no--scale supergravity global symmetries protect local supersymmetry and a zero value for the cosmological constant. We consider the breakdown of these symmetries and present a minimal SUGRA model motivated by the multiple point principle, in which the total vacuum energy density is naturally tiny. In order to reproduce the observed value of the cosmological constant and preserve gauge coupling unification, an additional pair of $5+\bar{5}$--plets of superfields has to be included in the particle content of the considered model. These extra fields have masses of the order of the supersymmetry breaking scale; so they can be detected at future colliders. We also discuss the supersymmetry breakdown and possible solution of the cosmological constant problem by MPP in models with an enlarged gauge symmetry.
1. Predictions for Four Generations of Quarks Suggested by the Approach Unifying Spins and Charges (M. Breskvar, J. Mravlje, N.Mankoc Borstnik), 2. No-scale Supergravity and the Multiple Point Principle (C.Froggatt, L.Laperashvili, R.Nevzorov, H.B.Nielsen), 3. The Two-Higgs Doublet Model and the Multiple Point Principle (C.Froggatt, L.Laperashvili, R.Nevzorov, H.B.Nielsen, M.Sher), 4. New Physics From a Dynamical Volume Element (E. Guendelman, A. Kaganovich, E. Nissimov and S. Pacheva), 5. Randomness in Random Dynamics (A. Kleppe), 6. An Example of Kaluza-Klein-like Theories Leading After Compactification to Massless Spinors Coupled to a Gauge Field-Derivations and Proofs (N. Mankoc Borstnik, H. B. Nielsen and D. Lukman), 7. Geometry Decides Gravity, Demanding General Relativity-it is Thus the Quantum Theory of Gravity (R. Mirman), 8. Physics Would Be Impossible in Any Dimension But 3+1 - There Could Be Only Empty Universes (R. Mirman),9. Conservation of Energy Prohibits Proton Decay (R. Mirman), 10. Approximate Solutions for the Higgs Masses and Couplings in the NMSSM (R. Nevzorov and D.J. Miller)
We review symmetries protecting a zero value for the cosmological constant in no--scale supergravity and reveal the connection between the Multiple Point Principle, no--scale and superstring inspired models.
The tiny order of magnitude of the cosmological constant is sought to be explained in a model involving the following ingredients: supersymmetry breaking in N=1 supergravity and the multiple point principle. We demonstrate the viability of this scenario in the minimal SUGRA model.