The primordial deuterium abundance: subDLA system at $z_{\rm abs}=2.437$
  towards the QSO J1444+2919
  We report a new detection of neutral deuterium in the sub Damped Lyman Alpha
system with low metallicity [O/H]\,=\,$-2.042 \pm 0.005$ at $z_{\rm abs}=2.437$
towards QSO~J\,1444$+$2919. The hydrogen column density in this system is
log$N$(H\,{\sc i})~$=19.983\pm0.010$ and the measured value of deuterium
abundance is log(D/H)~$=-4.706\pm0.007_{\rm stat}\pm0.067_{\rm syst}$. This
system meets the set of strict selection criteria stated recently by Cooke et
al. and, therefore, widens the {\it Precision Sample} of D/H. However, possible
underestimation of systematic errors can bring bias into the mean D/H value
(especially if use a weighted mean). Hence, it might be reasonable to relax
these selection criteria and, thus, increase the number of acceptable
absorption systems with measured D/H values. In addition, an unweighted mean
value might be more appropriate to describe the primordial deuterium abundance.
The unweighted mean value of the whole D/H data sample available to date (15
measurements) gives a conservative value of the primordial deuterium abundance
(D/H)$_{\rm p}=(2.55\pm 0.19)\times10^{-5}$ which is in good agreement with the
prediction of analysis of the cosmic microwave background radiation for the
standard Big Bang nucleosynthesis. By means of the derived (D/H)$_{\rm p}$
value the baryon density of the Universe $\Omega_{\rm b}h^2=0.0222\pm0.0013$
and the baryon-to-photon ratio $\eta_{10} = 6.09\pm 0.36$ have been deduced.
These values have confident intervals which are less stringent than that
obtained for the {\it Precision Sample} and, thus, leave a broader window for
new physics. The latter is particularly important in the light of the lithium
problem.
