  We suggest that the solution to the cosmological vacuum energy puzzle does
not require any new field beyond the standard model, but rather can be
explained as a result of the interaction of the infrared sector of the
effective theory of gravity with standard model fields. The cosmological
constant in this framework can be presented in terms of QCD parameters and the
Hubble constant $H$ as follows, $\epsilon_{vac} \sim H \cdot m_q\la\bar{q}q\ra
/m_{\eta'} \sim (4.3\cdot 10^{-3} \text{eV})^4$, which is amazingly close to
the observed value today. In this work we explain how this proposal can be
tested by analyzing CMB data. In particular, knowing the value of the observed
cosmological constant fixes univocally the smallest size of the spatially flat,
constant time 3d hypersurface which, for instance in the case of an effective
1-torus, is predicted to be around 74 Gpc. We also comment on another important
prediction of this framework which is a violation of cosmological isotropy.
Such anisotropy is indeed apparently observed by WMAP, and will be confirmed
(or ruled out) by future PLANCK data.
