Related papers: Cosmological Constraints on Unparticles as Continu…
An internally thermalized dark matter (DM) with only gravitational interaction with the standard model (SM) particles at low temperatures, may undergo number-changing self-scatterings in the early Universe, eventually freezing out to the…
We regard the background of space-time as a physical system composed of discrete volume elements at the Planck scale and get the internal energy of space-time by Debye model. A temperature-dependent minimum energy limit of the particles is…
Nearly conformal dynamics at the TeV scale as motivated by the hierarchy problem can be characterized by a stage of significant supercooling at the electroweak epoch. This has important cosmological consequences. In particular, a common…
We derive general constraints on the relic abundances of a long-lived particle which mainly decays into a neutrino (and something else) at cosmological time scales. Such an exotic particle may show up in various particle-physics models…
At present, the strongest upper limit on $\sum m_{\nu}$, the sum of neutrino masses, is from cosmological measurements. However, this bound assumes that the neutrinos are stable on cosmological timescales, and is not valid if the neutrino…
Searches for Dark Matter at the LHC are commonly described in terms of simplified models with scalar, pseudo-scalar, vector and axial-vector mediators. In this work we explore the constraints imposed on such models from the observed Dark…
The cold dark matter may be in a meta-stable state and decays to other particles with a very long lifetime. If the decaying products of the dark matter are weakly interacting, e.g. neutrinos, then it would have little impact on…
We consider the viability of new heavy gauge singlet scalar particles at colliders such as the LHC. Our original motivation for this study came from the possibility of a new heavy particle of mass ~ TeV decaying significantly into two…
We consider a nonsingular deflationary cosmological model with decaying vacuum energy density in universes of arbitrary spatial curvature. Irrespective of the value of $k$, the models are characterized by an arbitrary time scale $H_I^{-1}$…
The experimental data, as well as theoretical considerations allow (and, in some cases, require) the Universe at present to rest in a false vacuum, whose approximate stability imposes constraints on the model parameters. Under very general…
Unparticle physics has been an active field since the seminal work of Georgi. Recently, many constraints on unparticles from various observations have been considered in the literature. In particular, the cosmological constraints on the…
The expansion history and thermal physical process that happened in the early Universe before big bang nucleosynthesis (BBN) remains relatively unconstrained by observations. Low reheating temperature universes with normalcy temperatures of…
Up-to-date estimates of the cosmological parameters are presented as a result of numerical simulations of cosmic microwave background and large scale structure, considering a flat Universe in which the dark matter is made entirely or partly…
We show that a nonstandard cosmological history with a period of early matter domination driven by a sub-TeV visible-sector particle can arise rather naturally. This scenario involves a long-lived standard model singlet that acquires a…
The case for small neutrino mass differences from atmospheric and solar neutrino oscillation experiments has become compelling, but leaves the overall neutrino mass scale m_nu undetermined. The most restrictive limit of m_nu < 0.8 eV arises…
We present a complete analysis of the cosmological constraints on decaying dark matter. Previous analyses have used the cosmic microwave background and Type Ia supernova. We have updated them with the latest data as well as extended the…
We reconsider the dynamics of the Universe in the presence of interactions in the cosmological dark sector. A class of interacting models is introduced via a real function $f\left(r\right)$ of the ratio $r$ between the energy densities of…
We explore the observational adequacy of a class of Unified Dark Energy/Matter (UDE/M) models with a fast transition. Our constraints are set using a combination of geometric probes, some low redshift ones, and some high redshift ones (CMB…
As one of the fundamental unknowns of our Universe, the mass of dark matter remains to be a topic of great interest. We consider the possibility of a time-variation of the dark matter mass. We study the cosmological constraints on a model…
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…