We discuss a cosmological scenario with a stochastic background of gravitational waves sourced by the tensor perturbation due to a hybrid inflationary model with cubic potential. The tensor-to-scalar ratio for the present hybrid inflationary model is obtained as [Formula: see text]. Gravitational wave spectrum of this stochastic background, for large-scale CMB modes, [Formula: see text] to [Formula: see text] is studied. The present-day energy spectrum of gravitational waves [Formula: see text] is sensitively related to the tensor power spectrum and r which is, in turn, dependent on the unknown physics of the early cosmos. This uncertainty is characterized by two parameters: [Formula: see text] logarithmic average over the primordial tensor spectral index and [Formula: see text] logarithmic average over the effective equation-of-state parameter. Thus, exact constraints in the [Formula: see text]-[Formula: see text] plane can be obtained by comparing theoretical constraints of our model on r and [Formula: see text]. We obtain a limit on [Formula: see text] around the modes probed by CMB scales.

We introduce a novel evolutionary method that takes leverage from the MCMC method that can be used for constraining the parameters and theoretical models of Cosmology. Unlike the MCMC technique, which is essentially a non-parallel algorithm by design, the newly proposed algorithm is able to obtain the full potential of multi-core machines. With this algorithm, we could obtain the best-fit parameters of the ΛCDM cosmological model and identify the discrepancy in the Hubble parameter H 0 . In the present work we discuss the design principle of this novel approach and also the results from the analysis of Pantheon, OHD and Planck datasets are reported here. The estimation of parameters shows significant consistency with the previously reported values as well as a higher computational performance compared to the other similar exercises.

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