Related papers: Relaxing Cosmological Constraints on Large Extra D…
Baryogenesis in the models where the fundamental scale is as low as TeV in the context of large extra dimensions is a challenging problem. The requirement for the departure from thermal equilibrium necessarily ties any low scale…
In this report I consider the cosmology of KK gravitinos in models with extra dimensions, in particular in connection with the known non--standard high energy regime of expansion which is associated with them. The main result is that the…
A larger Planck scale during an early epoch leads to a smaller Hubble rate, which is the measure for efficiency of primordial processes. The resulting slower cosmic tempo can accommodate alternative cosmological histories. We consider this…
As an extension of previous works on classical tests of Kaluza-Klein (KK) gravity and as an attempt to find more stringent constraints on this theory, its effects on physical experiments and astronomical observations conducted in the Solar…
We study braneworlds in a five dimensional bulk, where cosmological expansion is mimicked by motion through AdS$_5$. We show that the five dimensional graviton reduces to the four dimensional one in the late time approximation of such…
Neutralino dark matter is well motivated, but also suffers from two shortcomings: it requires gravity-mediated supersymmetry breaking, which generically violates flavor constraints, and its thermal relic density \Omega is typically too…
Many efforts have been devoted to the studies of the phenomenology in particle physics with extra dimensions. We propose degenerate fermion stars with extra dimensions and study what features characterized by the size of extra dimensions…
We show that the LHC will be able to differentiate between a four-dimensional model with quantum gravity at ~1 TeV where the (massless) graviton becomes strongly coupled to standard model particles at 1 TeV and brane world type models with…
Axions with mass greater than 0.7 eV are excluded by cosmological precision data because they provide too much hot dark matter. While for masses above 20 eV the axion lifetime drops below the age of the universe, we show that the…
We present a full one-loop calculation of the gravitino thermal production rate, beyond the so-called hard thermal loop approximation, using the corresponding thermal spectral functions in numerical form on both sides of the light cone.…
In models with the fundamental gravity scale in the TeV range, early cosmology is quite different from the standard picture, because the universe must have arisen at a much lower temperature and the electroweak symmetry was probably never…
Extra-dimensional theories contain a number of almost degenerate states at each Kaluza-Klein level. If extra dimensional momentum is at least approximately conserved then the phenomenology of such nearly degenerate states depends crucially…
We examine in the context of supersymmetric models whether the usual cosmological upper bound on the axion decay constant can be relaxed by assuming a period of stronger QCD in the early universe. By evaluating the axion potential in the…
This article reviews basic construction and cosmological implications of a power-counting renormalizable theory of gravitation recently proposed by Horava. We explain that (i) at low energy this theory does not exactly recover general…
It is shown that the equalization of temperatures between our and mirror sectors occurs during one Hubble time due to microscopic black hole production and evaporation in particle collisions if the temperature of the Universe is near the…
I discuss the recent work done in collaboration with Chris Hill, Jing Wang and Hsin-Chia Cheng. We construct four-dimensional renormalizable gauge theories which, in their infrared limit, generate the dynamics of gauge interactions in flat…
Light gravitinos of mass $\lesssim \mathcal{O} (10)$ eV are of particular interest in cosmology, offering various baryogenesis scenarios without suffering from the cosmological gravitino problem. The gravitino may contribute considerably to…
We investigate gravitino dark matter produced thermally at high temperatures and in decays of a long-lived sneutrino. We consider the Non-Universal Higgs Model and a generalized gauge mediation model, and in each case identify sneutrino…
We show that the bound from the electroweak data on the size of extra dimensions accessible to all the standard model fields is rather loose. These "universal" extra dimensions could have a compactification scale as low as 300 GeV for one…
We review current cosmological constraints on the axion. We describe the basic mechanisms by which axions are created in the early universe, focussing on the standard thermal scenario where the dominant process is through axion radiation by…