Post-WMAP Assessment of Infrared Cutoff in the Primordial Spectrum from Inflation

The recent Cosmic Microwave Background (CMB) measurements indicate that there is power deficiency of the CMB anisotropies at large scales compared with the $\Lambda$CDM model. We have investigated the possibility of explaining such effects by a class of primordial power spectra which have infrared cutoffs close to the horizon scale. The primordial power spectrum recovered by direct deconvolution of the observed CMB angular spectrum indicates that the data prefers a sharp infrared cutoff with a localized excess (bump) just above the cutoff. We have been motivated to assess plausible extensions of simplest inflationary scenarios which readily accommodate similar form of infrared cutoff. We carry out a complete Bayesian analysis of the parameter space using {\it Markov Chain Monte Carlo} technique with such a class of primordial power spectra. We show that primordial power spectrum that have features such as an infrared cutoff followed by a subsequent excess in power give better fit to the observed data compared to a nearly scale-invariant power law or power spectrum with just a monotonic infrared cutoff. However, there is substantial room for improvement in the match to data and calls for exploration of other mechanisms that may lead to infrared cutoff even closer to that recovered by direct deconvolution approach.Comment: Changes to match version accepted for publication in PR

Quantum Disentangled Liquids

We propose and explore a new finite temperature phase of translationally invariant multi-component liquids which we call a "Quantum Disentangled Liquid" (QDL) phase. We contemplate the possibility that in fluids consisting of two (or more) species of indistinguishable quantum particles with a large mass ratio, the light particles might "localize" on the heavy particles. We give a precise, formal definition of this Quantum Disentangled Liquid phase in terms of the finite energy density many-particle wavefunctions. While the heavy particles are fully thermalized, for a typical fixed configuration of the heavy particles, the entanglement entropy of the light particles satisfies an area law; this implies that the light particles have not thermalized. Thus, in a QDL phase, thermal equilibration is incomplete, and the canonical assumptions of statistical mechanics are not fully operative. We explore the possibility of QDL in water, with the light proton degrees of freedom becoming "localized" on the oxygen ions. We do not presently know whether a local, generic Hamiltonian can have eigenstates of the QDL form, and if it can not, then the non-thermal behavior discussed here will exist as an interesting crossover phenomena at time scales that diverge as the ratio of the mass of the heavy to the light species also diverges.Comment: 14 page

Currency Returns, Institutional Investor Flows, and Exchange Rate Fundamentals

We explore the interaction between exchange rates, institutional investor currency flows and exchange-rate fundamentals. We find that these flows are highly correlated with contemporaneous and lagged exchange rate changes, and that they carry information for future excess currency returns. This information, however, is not strongly linked to future fundamentals. Flows are important in understanding transitory elements of excess returns, which include short-run underreaction and long-run overreaction. However, flows have a zero or negative correlation with permanent components of excess returns. We find that measured fundamentals - not flows - seem important in understanding permanent elements of excess returns. We conclude that investor flows are important for understanding deviations of exchange rates from fundamentals, but not for understanding the long-run currency values.

Currency Returns, Institutional Investor Flows, and Exchange Rate Fundamentals

We explore the interaction between exchange rates, institutional investor currency flows and exchange-rate fundamentals. We find that these flows are highly correlated with contemporaneous and lagged exchange rate changes, and that they carry information for future excess currency returns. This information, however, is not strongly linked to future fundamentals. Flows are important in understanding transitory elements of excess returns, which include short-run underreaction and long-run overreaction. However, flows have a zero or negative correlation with permanent components of excess returns. We find that measured fundamentals - not flows - seem important in understanding permanent elements of excess returns. We conclude that investor flows are important for understanding deviations of exchange rates from fundamentals, but not for understanding the long-run currency values.

The SST Fully-Synchronous Multi-GHz Analog Waveform Recorder with Nyquist-Rate Bandwidth and Flexible Trigger Capabilities

The design and performance of a fully-synchronous multi-GHz analog transient waveform recorder I.C. ("SST") with fast and flexible trigger capabilities is presented. The SST's objective is to provide multi-GHz sample rates with intrinsically-stable timing, Nyquist-rate sampling and high trigger bandwidth, wide dynamic range and simple operation. Containing 4 channels of 256 samples per channel, the SST is fabricated in an inexpensive 0.25 micrometer CMOS process and uses a high-performance package that is 8 mm on a side. It has a 1.9V input range on a 2.5V supply, exceeds 12 bits of dynamic range, and uses ~128 mW while operating at 2 G-samples/s and full trigger rates. With a standard 50 Ohm input source, the SST exceeds ~1.5 GHz -3 dB bandwidth. The SST's internal sample clocks are generated synchronously via a shift register driven by an external LVDS oscillator running at half the sample rate (e.g., a 1 GHz oscillator yields 2 G-samples/s). Because of its purely-digital synchronous nature, the SST has ps-level timing uniformity that is independent of sample frequencies spanning over 6 orders of magnitude: from under 2 kHz to over 2 GHz. Only three active control lines are necessary for operation: Reset, Start/Stop and Read-Clock. When operating as common-stop device, the time of the stop, modulo 256 relative to the start, is read out along with the sampled signal values. Each of the four channels integrates dual-threshold trigger circuitry with windowed coincidence features. Channels can discriminate signals with ~1mV RMS resolution at >600 MHz bandwidth.Comment: 3 pages, 6 figures, 1 table, submitted for publication in the Conference Record of the 2014 IEEE Nuclear Science Symposium, Seattle, WA, November 201

Superspace formulation and correlation functions of 3d superconformal field theories

We study $3d$ SCFTs in the superspace formalism and discuss superfields and on-shell higher spin current multiplets in free $3d$ SCFTs with $\mathcal{N}= 1,2,3,4$ and $6$ superconformal symmetry. For $\mathcal{N}=1$ 3d SCFTs we determine the superconformal invariants in superspace needed for constructing 3-point functions of higher spin operators, find the non-linear relations between the invariants and consequently write down all the independent invariant structures, both parity even and odd, for various 3-point functions of higher spin operators.Comment: typos corrected, references added. Accepted for publication in JHE

The Odd-Parity CMB Bispectrum

Measurement of the cosmic microwave background (CMB) bispectrum, or three-point correlation function, has now become one of the principle efforts in early-Universe cosmology. Here we show that there is a odd-parity component of the CMB bispectrum that has been hitherto unexplored. We argue that odd-parity temperature-polarization bispectra can arise, in principle, through weak lensing of the CMB by chiral gravitational waves or through cosmological birefringence, although the signals will be small even in the best-case scenarios. Measurement of these bispectra requires only modest modifications to the usual data-analysis algorithms. They may be useful as a consistency test in searches for the usual bispectrum and to search for surprises in the data.Comment: 5 pages, 1 figur

Weak Mott insulators on the triangular lattice: possibility of a gapless nematic quantum spin liquid

We study the energetics of Gutzwiller projected BCS states of various symmetries for the triangular lattice antiferromagnet with a four particle ring exchange using variational Monte Carlo methods. In a range of parameters the energetically favored state is found to be a projected $d_{x^2-y^2}$ paired state which breaks lattice rotational symmetry. We show that the properties of this nematic or orientationally ordered paired spin liquid state as a function of temperature and pressure can account for many of the experiments on organic materials. We also study the ring-exchange model with ferromagnetic Heisenberg exchange and find that amongst the studied ans\"atze, a projected $f-$wave state is the most favorable.Comment: Longer version, 7+ pages, 5 figure

Joint Planck and WMAP Assessment of Low CMB Multipoles

The remarkable progress in cosmic microwave background (CMB) studies over past decade has led to the era of precision cosmology in striking agreement with the $\Lambda$CDM model. However, the lack of power in the CMB temperature anisotropies at large angular scales (low-$\ell$), as has been confirmed by the recent Planck data also (up to $\ell=40$), although statistically not very strong (less than $3\sigma$), is still an open problem. One can avoid to seek an explanation for this problem by attributing the lack of power to cosmic variance orcan look for explanations i.e., different inflationary potentials or initial conditions for infl ation to begin with, non-trivial topology, ISW effect etc. Features in the primordial power spectrum (PPS) motivated by the early universe physics has been the most common solution to address this problem. In the present work we also follow this approach and consider a set of PPS which have features and constrain the parameters of those using WMAP 9 year and Planck data employing Markov-Chain Monte Carlo (MCMC) analysis. The prominent feature of all the models of PPS that we consider is an infra-red cut off which leads to suppression of power at large angular scales. We consider models of PPS with maximum three extra parameters and use Akaike information criterion ($AIC$) and Bayesian information criterion ($BIC$) of model and Bayesian information criterion ($BIC$) of model selection to compare the models. For most models, we find good constraints for the cut off scale $k_c$, however, for other parameters our constraints are not that good. We find that sharp cut off model gives best likelihood value for the WMAP 9 year data, but is as good as power law model according to $AIC$. For the joint WMAP 9+Planck data set, Starobinsky model is slightly preferred by $AIC$ which is also able to produce CMB power suppression up to $\ell\leq30$ to some extent.Comment: 27 pages, 10 figures, 3 tables, matches with the published version, abstract is shortened to keep it within arXiv's limit (1920 characters

Statistical Isotropy of CMB Polarization Maps

We formulate statistical isotropy of CMB anisotropy maps in its most general form. We also present a fast and orientation independent statistical method to determine deviations from statistical isotropy in CMB polarization maps. Importance of having statistical tests of departures from SI for CMB polarization maps lies not only in interesting theoretical motivations but also in testing cleaned CMB polarization maps for observational artifacts such as residuals from polarized foreground emission. We propose a generalization of the Bipolar Power Spectrum (BiPS) to polarization maps. Application to the observed CMB polarization maps will be soon possible after the release of WMAP three year data. As a demonstration we show that for E-polarization this test can detect breakdown of statistical isotropy due to polarized synchrotron foreground.Comment: 6 pages, 2 figures, Conclusions & results unchanged; Extension to cutsky included (discussion & references added); Matches version accepted to Phys. Rev. D Rapid Com