Primordial Non-Gaussianities of inflationary step-like models

We use Minkowski Functionals to explore the presence of non-Gaussian signatures in simulated cosmic microwave background (CMB) maps. Precisely, we analyse the non-Gaussianities produced from the angular power spectra emerging from a class of inflationary models with a primordial step-like potential. This class of models are able to perform the best-fit of the low-$\ell$ `features', revealed first in the CMB angular power spectrum by the WMAP experiment and then confirmed by the Planck collaboration maps. Indeed, such models generate oscillatory features in the primordial power spectrum of scalar perturbations, that are then imprinted in the large scales of the CMB field. Interestingly, we discover Gaussian deviations in the CMB maps simulated from the power spectra produced by these models, as compared with Gaussian $\Lambda$CDM maps. Moreover, we also show that the kind and level of the non-Gaussianities produced in these simulated CMB maps are compatible with that found in the four foreground-cleaned Planck maps. Our results indicate that inflationary models with a step-like potential are not only able to improve the best-fit respect to the $\Lambda$CDM model accounting well for the `features' observed in the CMB angular power spectrum, but also suggesting a possible origin for certain non-Gaussian signatures observed in the Planck data.Comment: 15 pages, 9 figure

Comb entanglement in quantum spin chains

Bipartite entanglement in the ground state of a chain of $N$ quantum spins can be quantified either by computing pairwise concurrence or by dividing the chain into two complementary subsystems. In the latter case the smaller subsystem is usually a single spin or a block of adjacent spins and the entanglement differentiates between critical and non-critical regimes. Here we extend this approach by considering a more general setting: our smaller subsystem $S_A$ consists of a {\it comb} of $L$ spins, spaced $p$ sites apart. Our results are thus not restricted to a simple `area law', but contain non-local information, parameterized by the spacing $p$. For the XX model we calculate the von-Neumann entropy analytically when $N\to \infty$ and investigate its dependence on $L$ and $p$. We find that an external magnetic field induces an unexpected length scale for entanglement in this case.Comment: 6 pages, 4 figure

Balance Sheet Effects in Currency Crises: Evidence from Brazil

In third generation currency crises models, balance sheet losses from currency depreciations propagate the crises into the real sector of the economy. To test these models, we built a firmlevel database that allowed us to measure currency mismatches around the 2002 Brazilian currency crisis. We found that between 2001 and 2003, firms with large currency mismatches just before the crisis reduced their investment rates 8.1 percentage points more than other publicly held firms. We also showed that the currency depreciation increased exporters revenue, but those with currency mismatches reduced investments 12.5 percentage points more than other exporters. These estimated reductions in investment are economically very significant, underscoring the importance of negative balance sheet effects in currency crises. Jel Codes:F32; F34; G31; G32Investment; Balance sheets; Currency crises; Hedge; Financial constraints.

Balance Sheet Effects in Currency Crises: Evidence from Brazil

"Third-generation currency crises models" argue that capital losses from exchange-rate depreciation propagate the crises to the productive sector. To test these models, we use a firm-level dataset that allows us to measure currency mismatches around the 2002 Brazilian currency crisis. We find that, between 2001 and 2003, firms that shortly before the crisis had large currency mismatches decreased their investment rates by 8.1 percentual points, relatively to other public firms. Moreover, we show that the currency depreciation implied large competitive gains for the exporters, and yet the investment of exporters with large currency mismatches fell by 12.5 percentual points, relatively to other exporters. The estimated falls in investment are economically very relevant, thereby corroborating the relevance of third generation models negative balance sheet effects.