'Constraint consistency' at all orders in Cosmological perturbation theory

We study the equivalence of two - order-by-order Einstein's equation and Reduced action - approaches to cosmological perturbation theory at all orders for different models of inflation. We point out a crucial consistency check which we refer to as 'Constraint consistency' that needs to be satisfied. We propose a quick and efficient method to check the consistency for any model including modified gravity models. Our analysis points out an important feature which is crucial for inflationary model building i.e., all `constraint' inconsistent models have higher order Ostrogradsky's instabilities but the reverse is not true. In other words, one can have models with constraint lapse function and shift vector, though it may have Ostrogradsky's instabilities. We also obtain the single variable equation for non-canonical scalar field in the limit of power-law inflation for the second-order perturbed variables.Comment: 25 page

Developing ethnic identity questions for Understanding Society

Ethnic identity, its formation, expression and consequences are sources of extensive discussion and debate within multicultural societies. Analysis of identity is increasingly finding its way into survey based analysis and is being explored by disciplines beyond psychology, and qualitative and theoretical sociology. However, effective and appropriate survey measures of ethnic identity that are suitable for inclusion in a general purpose sample survey and which allow estimation of change and development across the age range are in short supply. Here, we describe the process of development of a series of new ethnic identity questions, designed specifically for inclusion in Understanding Society but with applicability for longitudinal studies further afield. We detail the rationale for the development and the process by which the final set of questions was arrived at, and outline the implications for future research agendas

Effect of interview modes on measurement of identity

In this paper, we investigate the effect of interview mode on responses to attitudinal and autobiographical questions: a 13-item multidimensional identity module. We find small but significant mode effects of three to seven percentage points on the response pattern for the domains of national identity, religion, racial or ethnic background, political beliefs and sexual orientation. We also find very small but significant mode effects of one to two percentage points on item non-response for occupational identity and identification with father’s ethnic background. We conclude that mode effects on these questions can convincingly be interpreted as stemming from social desirability bias

Hybrid stars in the light of GW170817

We have studied the effect of tidal deformability constraint given by the binary neutron star merger event GW170817 on the equations of state (EOS) of hybrid stars. The EOS are constructed by matching the hadronic EOS described by relativistic mean field (RMF) model and parameter sets NL3, TM1 and NL3$\omega\rho$ with the quark matter EOS described by modified MIT bag model, via Gibbs' construction. It is found that the tidal deformability constraints along with the lower bound on maximum mass ($M_{\rm max}=2.01\pm0.04M_\odot$) significantly limit the bag model parameter space ($B_{\rm eff}^{1/4}$, $a_4$). We also obtain upper limits on the radius of $1.4M_\odot$ and $1.6M_\odot$ stars as $R_{1.4}\leq13.2-13.5$ km and $R_{1.6}\leq13.2-13.4$ km, respectively for different hadronic EOS considered here.Comment: version accepted by Ap