Ilya Gurwich

Radiation Driven Inflation

A novel, scalar-field-free approach to cosmic inflation is presented. The inflationary Universe and the radiation-dominated Universe are shown, within the framework of unified brane cosmology, to be two different phases governed by one and the same energy density. The phase transition of second order (the Hubble constant exhibits a finite jump) appears naturally and serves as the exit mechanism. No re-heating is needed. The required number of e-folds is achieved without fine tuning.

On the problem of vacuum energy in brane theories

We point out that modern brane theories suffer from a severe vacuum energy problem. To be specific, the Casimir energy associated with the matter fields confined to the brane, is stemming from the one and the same localization mechanism which forms the brane itself, and is thus generically unavoidable. Possible practical solutions are discussed, including in particular spontaneously broken supersymmetry, and quantum mechanically induced brane tension.

Natural Neutrino Dark Energy

1 construct a general description for neutrino dark energy models, that do not require exotic particles or strange couplings. With the help of the above, this class of models is reduced to a single function with several constraints. It is shown that these models lead to some concrete predictions that can be verified (or disproved) within the next decade, using results from PLANK, EUCLID and JDEM.

Artifact Dark Matter from Unified Brane Gravity

Adopting Diracs brane variation prescription, the energy-momentum tensor of a brane gets supplemented by a geometrical (embedding originated) dark component. While the masslessness of the graviton is preserved, and the Newton force law is recovered, the corresponding Newton constant is necessarily lower than the one which governs FRW cosmology. This has the potential to puzzle out cosmological dark matter, a subsequent conjecture concerning galactic dark matter follows.

Unified brane gravity: Cosmological dark matter from a scale dependent Newton constant

We analyze, within the framework of unified brane gravity, the weak-field perturbations caused by the presence of matter on a 3-brane. Although deviating from the Randall-Sundrum approach, the masslessness of the graviton is still preserved. In particular, the four-dimensional Newton force law is recovered, but serendipitously, the corresponding Newton constant is shown to be necessarily lower than the one which governs Friedmann-Robertson-Walker cosmology. This has the potential to puzzle out cosmological dark matter. A subsequent conjecture concerning galactic dark matter follows.

Einstein Corpuscles and Dark Core Black Holes in Spontaneously induced General Relativity

Suppose General Relativity, provocatively governed by a dimensional coupling constant, is a spontaneously Induced theory. In which case, black hole configurations are naively expected to get gracefully modified. For example, the exterior Schwarzschild solution is fully recovered at the GR‐limit of such a theory. Serendipitously, however, due to a phase transition, which takes place exactly at the would have been horizon, it connects with a novel dark core characterized by a varying Newton constant (the word ‘dark’ is borrowed from cosmology, where the one and the same theory gives rise to dark matter superimposed by a rippled structure). Once the strict GR‐limit is relaxed, localized Einstein‐style gravitational corpuscles (practically massless particle configurations with a Newton constant varying core) make their appearance; they become point‐like at the GR‐limit.

Quantum Gravity: A Novel Approach

In this contribution, I will show that a gravitational theory can be constructed from a bound state of spin 1 and spin 3 bosons rather than a single spin 2 graviton. I will show that such a theory can be constructed to give gravity as a low energy limit. I will also argue that such a theory suffers from less logarithmic divergences and no quadratic divergences at all. I will address also the unsolved issues in this theory and give some theoretical as well as experimental applications of this theory.