Constraints on Cosmological Models from Hubble Parameters Measurements
  In this paper, we study the cosmological constraints from the measurements of
Hubble parameters---$H(z)$ data. Here, we consider two kinds of $H(z)$ data:
the direct $H_0$ probe from the Hubble Space Telescope (HST) observations of
Cepheid variables with $H_0=73.8\pm2.4$ ${\rm km\,s^{-1}\,Mpc^{-1}}$ and
several measurements on the Hubble parameter at high redshifts $H(z)$.
Employing Markov Chain Monte Carlo method, we also combine the WMAP nine-year
data (WMAP9), the baryon acoustic oscillations (BAO) and type Ia supernovae
(SNIa) "Union2.1" compilation to determine the cosmological parameters, such as
the equation of state (EoS) of dark energy $w$, the curvature of the universe
$\Omega_k$, the total neutrino mass $\sum{m_\nu}$, the effective number of
neutrinos $N_{\rm eff}$, and the parameters associated with the power spectrum
of primordial fluctuations. These $H(z)$ data provide extra information on the
accelerate rate of our Universe at high redshifts. Therefore, adding these
$H(z)$ data significantly improves the constraints on cosmological parameters,
such as the number of relativistic species. Moreover, we find that direct prior
on $H_0$ from HST can also give good constraints on some parameters, due to the
degeneracies between these parameters and $H_0$.
