In the N=1 four-dimensional new-minimal supergravity framework, we supersymmetrise the coupling of the scalar kinetic term to the Einstein tensor. This coupling, although introduces a non-minimal derivative interaction of curvature to matter, it does
not introduce harmful higher-derivatives. For this construction, we employ off-shell chiral and real linear multiplets. Physical scalars are accommodated in the chiral multiplet whereas curvature resides in a linear one.
We generalize the Cosmological Slingshot Scenario for a Slingshot brane moving in a Klebanov-Strassler throat. We show that the horizon and isotropy problems of standard cosmology are avoided, while the flatness problem is acceptably alleviated. Rega
rding the primordial perturbations, we identify their vacuum state and elucidate the evolution from the quantum to the classical regimes. Also, we calculate their exact power spectrum showing its compatibility with current data. We discuss the bouncing solution from a four dimensional point of view. In this framework the radial and angular motion of the Slingshot brane are described by two scalar fields. We show that the bouncing solution for the scale factor in String frame is mapped into a monotonically increasing (in conformal time) solution in the Einstein frame. We finally discuss about the regularity of the geometry in Einstein frame.
We consider a recently proposed scenario for the generation of primordial cosmological perturbations, the so called Cosmological Slingshot scenario. We firstly obtain a general expression for the Slingshot primordial power spectrum which extends prev
ious results by including a blue pre-bounce residual contribution at large scales. Starting from this expression we numerically compute the CMB temperature and polarization power spectra arising from the Slingshot scenario and show that they excellently match the standard WMAP 3-years best-fit results. In particular, if the residual blue spectrum is far above the largest WMAP observed scale, the Slingshot primordial spectrum fits the data well by only fixing its amplitude and spectral index at the pivot scale k_p=10^{-3}h x Mpc^{-1}. We finally show that all possible distinctive Slingshot signatures in the CMB power spectra are confined to very low multipoles and thus very hard to detect due to large cosmic variance dominated error bars at these scales.
We construct actions of higher spin fields interacting with gravity on AdS_5 backgrounds such that the Compton scattering amplitudes of the interaction are tree-level unitary. We then consider higher-spin fields in the Randall-Sundrum scenario. There
, in the fermionic case, we construct a tree-level unitary action of higher spin fields interacting with branes and linearised gravity. In the bosonic case we show that this is not in general possible. A tree-level unitary action of bosonic higher spins interacting with linearised gravity and branes is only possible in the following cases: The brane is a pure tension brane and/or Dirichlet boundary conditions are imposed thereby making bosonic higher spin fields invisible to a brane observer. We finally show that higher spins in Randall-Sundrum II braneworlds can only be produced by (decay into) gravitons at trans-Planckian scales. We end by commenting on the possible relevance of higher-spin unparticles as Dark Matter candidates.
