Confronting the concordance model of cosmology with Planck data

We confront the concordance (standard) model of cosmology, the spatially flat $\Lambda$CDM Universe with power-law form of the primordial spectrum with Planck CMB angular power spectrum data searching for possible smooth deviations beyond the flexibility of the standard model. The departure from the concordance cosmology is modeled in the context of Crossing statistic and statistical significance of this deviation is used as a measure to test the consistency of the standard model to the Planck data. Derived Crossing functions suggest the presence of some broad features in angular spectrum beyond the expectations of the concordance model. Our results indicate that the concordance model of cosmology is consistent to the Planck data only at 2 to 3$\sigma$ confidence level if we allow smooth deviations from the angular power spectrum given by the concordance model. This might be due to random fluctuations or may hint towards smooth features in the primordial spectrum or departure from another aspect of the standard model. Best fit Crossing functions indicate that there are lack of power in the data at both low-$\ell$ and high-$\ell$ with respect to the concordance model. This hints that we may need some modifications in the foreground modeling to resolve the significant inconsistency at high-$\ell$. However, presence of some systematics at high-$\ell$ might be another reason for the deviation we found in our analysis.Comment: 16 pages, 7 figures, 2 tables, matches final version published in JCA

Sharp inflaton potentials and bi-spectra: Effects of smoothening the discontinuity

Sharp shapes in the inflaton potentials often lead to short departures from slow roll which, in turn, result in deviations from scale invariance in the scalar power spectrum. Typically, in such situations, the scalar power spectrum exhibits a burst of features associated with modes that leave the Hubble radius either immediately before or during the epoch of fast roll. Moreover, one also finds that the power spectrum turns scale invariant at smaller scales corresponding to modes that leave the Hubble radius at later stages, when slow roll has been restored. In other words, the imprints of brief departures from slow roll, arising out of sharp shapes in the inflaton potential, are usually of a finite width in the scalar power spectrum. Intuitively, one may imagine that the scalar bi-spectrum too may exhibit a similar behavior, i.e. a restoration of scale invariance at small scales, when slow roll has been reestablished. However, in the case of the Starobinsky model (viz. the model described by a linear inflaton potential with a sudden change in its slope) involving the canonical scalar field, it has been found that, a rather sharp, though short, departure from slow roll can leave a lasting and significant imprint on the bi-spectrum. The bi-spectrum in this case is found to grow linearly with the wavenumber at small scales, a behavior which is clearly unphysical. In this work, we study the effects of smoothening the discontinuity in the Starobinsky model on the scalar bi-spectrum. Focusing on the equilateral limit, we analytically show that, for smoother potentials, the bi-spectrum indeed turns scale invariant at suitably large wavenumbers. We also confirm the analytical results numerically using our newly developed code BINGO. We conclude with a few comments on certain related points.Comment: v1: 28 pages, 4 figures; v2: 29 pages, 4 figures, Version to appear in JCA

Livestock Sector in North-Eastern Region of India: An Appraisal of Performance

Although agriculture is the prime source of livelihood for a majority of rural population in the North-Eastern region (NER) of India, dependence on livestock as an alternative source of income is significant. Responding to the burgeoning demand for livestock products in a sustainable manner is a big challenge. The widening gap between the demand and supply of livestock products can be met through bringing out changes in the production structure or opening up the international trade. In this context, an analysis of performance and factors influencing development of the livestock sector in NER has been carried out. The growth of livestock sector has been found slower in the NER than at the national level. However, a significant proportion of landless labourers, small and marginal farmers have access to livestock resources and acceleration in the growth of livestock in NER offers significant opportunities for household income augmentation and employment generation. Several factors identified to influence households’ decision to rear livestock include availability of labour, occupation, caste, farm-size, availability of irrigation, and access to information sources. The study has shown that the NE states should take technical, institutional and policy initiatives for the improvement of breeds, feed availability, disease control and food safety of livestock.Livestock Production/Industries,

Primordial features due to a step in the inflaton potential

Certain oscillatory features in the primordial scalar power spectrum are known to provide a better fit to the outliers in the cosmic microwave background data near the multipole moments of $\ell=22$ and 40. These features are usually generated by introducing a step in the popular, quadratic potential describing the canonical scalar field. Such a model will be ruled out, if the tensors remain undetected at a level corresponding to a tensor-to-scalar ratio of, say, $r\simeq 0.1$. In this work, in addition to the popular quadratic potential, we investigate the effects of the step in a small field model and a tachyon model. With possible applications to future datasets (such as PLANCK) in mind, we evaluate the tensor power spectrum exactly, and include its contribution in our analysis. We compare the models with the WMAP (five as well as seven-year), the QUaD and the ACBAR data. As expected, a step at a particular location and of a suitable magnitude and width is found to improve the fit to the outliers (near $\ell=22$ and 40) in all these cases. We point out that, if the tensors prove to be small (say, $r\lesssim 0.01$), the quadratic potential and the tachyon model will cease to be viable, and more attention will need to be paid to examples such as the small field models.Comment: 17 pages, 6 figures, Discussion shortened, Version to appear in JCA

Rural Employment Diversification in India: Trends, Determinants and Implications on Poverty

This paper has studied rural employment diversification in India and across major states using NSSO data at household level for the period 1983 and 2009-10. Factors affecting rural employment diversification towards non-farm sector have also been studied. Analysis has shown that the non-farm sector has consistently grown over time and employed nearly one-third of the rural workforce in 2009-10, as compared to merely one-fifth in 1983 at all-India level. The similar trend is seen across major states as well, though the pace and pattern varied widely. In providing employment to rural workforce, increasing dominance of crop production, followed by animal husbandry was observed across major states during 2009-10. The share of fishery and forestry was negligible in providing employment to the rural workforce. The study has revealed that the increasing rural non-farm employment has positive and significant effect on reducing rural poverty at all-India level. A positive link between income and employment has also been observed in diversifying towards horticultural activities. A well designed area-specific programme should be evolved to help improve skill of rural workforce, which in turn would benefit in getting employment in the non-farm sector.Rural employment, Employment diversification, Crop sector, Agricultural and Food Policy, J21, J23, O15, O18,