Proceedings of the

A general myth created by the * C*haotic * I*nflation, that * ``
T/S is negligible for the Harrison--Zel'dovich spectrum''*, proved to be an
artifact of the model, namely, the -potential-choice there (the
power-law inflation has demonstrated the consistency with the myth displaying
that large can be obtained only while rejecting from the

Obviously, it is clear that * T/S* becomes large if the cosmological
perturbations are generated at . In this case the inflation
must continue to smaller . This possibility is realised for a
rather general class of the fundamental inflations with one scalar field and
the effective -term (Lukash & Mikheeva (1996)):

The vacuum density () should be metastable (otherwise inflation will proceed infinitely) and decay at some . The mechanism of the decay may be arbitrary and is not fixed in this simple model (as an example of -decay see hybrid inflation, Linde (1994)).

Regarding that the inflation proceeds up to small , eq(2) can be relevantly understood as the decomposition of near the local-minimum-point .

**Figure 1:** The spectra of scalar () and tensor ()
metric perturbations in the model (2) with in arbitrary
normalisation. In the ``blue'' asymptotic .

Another important parameter of the model (besides ) is where . For

the process of the inflation is dominated by the -term. Such a stage,
being impossible in the chaotic inflation, brings about the generation of
``blue'' spectra of * S*-perturbations. Taking into account that for
the spectrum is ``red'', we come to very generic
properties of the * S* and * T* spectra in the models with
-term.

- The power-spectra of scalar perturbations have a broad minimum near , corresponding to .
- Nearby the minimum of
*S*-perturbations the amplitudes of both modes,*S*and*T*, are close to each other, so the expected*T/S*get its maximum when measured at those scales ( for COBE). - In the region where
- the effective spectrum of temperature fluctuations is close to
*HZ*-one; - the local slope of
*S*-mode is scale-free: ; - the deviation of
*T*-mode from the HZ-spectrum gets its maximum.

- the effective spectrum of temperature fluctuations is close to
- The approximation works well at any scale, where
should be understood as the effective (local) spectral index of the
*T*-mode where*T/S*is measured.

**Figure 2:** * T/S* ratio for the model (2) with
.

Figure 1 presents * S* and * T* perturbation spectra (dashed and
solid lines, respectively) and a ratio between them (dotted line). The
gauge-invariant metric perturbations generated in the inflation, are determined
in the synchronous reference system comoving to the -field in large
scales ():

where and are random Gaussian functions of spatial coordinates, ,

For * HZ*-spectra and would be -independent ( and
, respectively). The normalisation of both spectra is arbitrary and
can be calculated exactly after defining .

For the case , , * T/S* was calculated by the authors
for the following model parameters: , (Figure 2). Figure 3 shows the same
two-parametric function * T/S* as a set of the slices of constant * T/S*
values. We see that the probability to find in the model
plane is roughly 50%.

As the ``blue'' * S*-spectra appearing naturally in the -dominated
inflation models have important implications for * LSS* formation theories,
below we write down explicitly ().

For :

For :

For the dimensionless power spectrum of density perturbations is as follows:

Wed Jul 23 11:53:34 BST 1997