Structure Formation by Fifth Force: Power Spectrum from N-Body Simulations (2009)
Zhao, HongSheng, Maccio', Andrea, Li, Baojiu, Hoekstra, Henk, Feix, Martin
We lay out the framework to numerically study nonlinear structure formation in the context of scalar-field-coupled cold dark matter models (phiCDM models) where the scalar field phi serves as...
Structure Formation by Fifth Force I: N-Body vs. Linear Simulations (2009)
We lay out the frameworks to numerically study the structure formation in both linear and nonlinear regimes in general dark-matter-coupled scalar field models, and give an explicit example where the...
A Realistic Cosmology Without Cold Dark Matter (2009)
We propose a new framework unifying cold dark matter (CDM) and Modified Newtonian Dynamics (MOND) to solve their respective problems on galactic scales and large scale structure formation. In our...
Does Bulk Viscosity Create a Viable Unified Dark Matter Model? (2009)
We investigate in detail the possibility that a single imperfect fluid with bulk viscosity can replace the need for separate dark matter and dark energy in cosmological models. With suitable choices...
Varying-Alpha Cosmologies with Potentials (2008)
We generalize the Bekenstein-Sandvik-Barrow-Magueijo (BSBM) model for the variation of the fine structure 'constant', $\alpha ,$ to include an exponential or inverse power-law self-potential for the...
Testing Alternative Theories of Dark Matter with the CMB (2008)
Li, Baojiu, Barrow, John D., Mota, David F., Zhao, HongSheng
We propose a method to study and constrain modified gravity theories for dark matter using CMB temperature anisotropies and polarization. We assume that the theories considered here have already...
Microscopic and Macroscopic Behaviors of Palatini Modified Gravity Theories (2008)
Li, Baojiu, Mota, David F., Shaw, Douglas J.
We show that, within modified gravity, the non-linear nature of the field equations implies that the usual naive averaging procedure (replacing the microscopic energy-momentum by its cosmological...
Empirical theories of Dark Matter like MOND gravity and of Dark Energy like f(R) gravity were motivated by astronomical data. But could these theories be branches rooted from a more general hence...
Indistinguishable Macroscopic Behaviour of Palatini Gravities and General Relativity (2008)
Li, Baojiu, Mota, David F., Shaw, Douglas J.
We show that, within some modified gravity theories, such as the Palatini models, the non-linear nature of the field equations implies that the usual naive averaging procedure (replacing the...
Halle, Anaelle, Zhao, HongSheng, Li, Baojiu
We propose a unified single-field description of the galactic Dark Matter and various uniform scalar fields for the inflation and cosmological constant. The two types of effects could originate from...
Detecting a Lorentz-Violating Field in Cosmology (2007)
Li, Baojiu, Mota, David F., Barrow, John D.
We consider cosmology in the Einstein-aether theory (the generally covariant theory of gravitation coupled to a dynamical timelike Lorentz-violating vector field) with a linear aether-Lagrangian. The...
The Cosmology of Ricci-Tensor-Squared Gravity in the Palatini Variational Approach (2007)
Li, Baojiu, Barrow, John D., Mota, David F.
We consider the cosmology of the Ricci-tensor-squared gravity in the Palatini variational approach. The gravitational action of standard general relativity is modified by adding a function...
The Cosmology of Modified Gauss-Bonnet Gravity (2007)
Li, Baojiu, Barrow, John D., Mota, David F.
We consider the cosmology where some function f(G) of the Gauss-Bonnet term G is added to the gravitational action to account for the late-time accelerating expansion of the universe. The covariant...
The Cosmology of f(R) Gravity in the Metric Variational Approach (2007)
We consider the cosmologies that arise in a subclass of f(R) gravity with f(R)=R+\mu ^{2n+2}/(-R)^{n} and -1
Constraints on f(R) Cosmology in the Palatini Formalism (2006)
In this work we derive the covariant and gauge invariant perturbation equations in general theories of $f(R)$ gravity in the Palatini formalism to linear order and calculate the cosmic microwave...
CMB and Matter Power Spectra of Early f(R) Cosmology in Palatini Formalism (2006)
We calculate in this article the CMB and matter power spectra of a class of early $f(R)$ cosmologies, which takes the form of $f(R) = R + \lambda_1 H_0^2\text{exp}[R/(\lambda_2 H_0^2)]$. Unlike the...
Big Bang Nucleosynthesis with an Evolving Radion in the Brane World Scenario (2005)
We consider the big bang nucleosynthesis (BBN) in the Brane world scenario, where all matter fields are confined on our 3-brane and the radion of the Brane evolves cosmologically. In the Einstein...
The successful prediction of light element abundances from Big Bang Nucleosynthesis has been a pillar of the standard model of Cosmology. Because many of the relevant reaction rates are sensitive to...
Dark Energy as a Signature of Extra Dimensions (2005)
Li, Baojiu, Chu, Ming-Chung, Cheung, Kai-Chung, Tang, Alfred
One of the most important and surprising discoveries in cosmology in recent years is the realization that our Universe is dominated by a mysterious dark energy, which leads to an accelerating...