Moment Of Inflation Research Articles

Inflation and gauge field holonomy

We discuss a novel scenario for early cosmology, when the inflationary quasi-de Sitter phase dynamically originates from the initial quantum state represented by the microcanonical density matrix. This genuine quantum effect occurs as a result of the dynamics of the topologically nontrivial sectors in a (conjectured) strongly coupled QCD-like gauge theory in expanding universe. The crucial element of our proposal is the presence in our framework of a nontrivial $\mathbb{S}^1$ which plays the dual role in construction: it defines the periodic gravitational instanton (on the gravity side) and it also defines a nontrivial gauge holonomy (on the gauge side) generating the vacuum energy. The effect is global in nature and cannot be formulated in terms of a gradient expansion in an effective local field theory. We also discuss a graceful exit from holonomy inflation due to the helical instability. The number of e-folds in the holonomy inflation framework is determined by the gauge coupling constant at the moment of inflation, and estimated as $N_{\rm infl}\sim \alpha^{-2}(H_0)\sim 10^2$. We also comment on the relation of our framework with the no-boundary and tunneling cosmological proposals and their recent criticism.

Moment matching versus Bayesian estimation: Backward-looking behaviour in a New-Keynesian baseline model

The paper considers an elementary New-Keynesian three-equation model and compares its Bayesian estimation based on conventional priors to the results from the method of moments (MM), which seeks to match a finite set of the model-generated second moments of inflation, output and the interest rate to their empirical counterparts. It is found that in the Great Inflation (GI) period—though not quite in the Great Moderation (GM)—the two estimations imply a significantly different covariance structure. Regarding the parameters, special emphasis is placed on the degree of backward-looking behaviour in the Phillips curve. While, in line with much of the literature, it plays a minor role in the Bayesian estimations, MM yields values of the price indexation parameter close to or even at its maximal value of unity. For both GI and GM, these results are worth noticing since in (strong or, respectively, weak) contrast to the Bayesian parameters, the covariance matching thus achieved appears rather satisfactory.

Cosmological perturbations inQCD¯-inflation: Estimates confronting the observations, including BICEP2

We discuss a new scenario for early cosmology, when inflationary de Sitter phase dynamically emergent. This genuine quantum effect occurs as a result of dynamics of the topologically nontrivial sectors in a (conjectured) strongly coupled QCD- like gauge theory with scale ${\Lambda_{\overline{\mathrm{QCD}}}} \sim 10^{17} $ GeV in expanding universe. Inflaton in this ${\overline{\mathrm{QCD}}}$- inflation framework is an auxiliary non-propagating field, similar to an effective field known to emerge in topologically ordered condensed matter systems. Number of e-folds in the ${\overline{\mathrm{QCD}}}$-inflation framework is determined by the gauge coupling constant at the moment of inflation, and estimated as $N_{\rm inf}\sim \alpha^{-2}(H_0)\sim 10^2$. We analyze the equation of state in this framework at the end of inflation in terms of the gauge dynamics and confront our estimates with observations. We make predictions for the tensor tilt, $n_t \simeq -0.02$, the running of the tensor tilt $\alpha_t= {\partial n_t}/{\partial \ln k}\sim \alpha^4(H_0)\sim 10^{-4}$ and the running for the spectral index $\alpha_s= {\partial n_s}/{\partial \ln k}\sim \alpha^4(H_0)\sim 10^{-4}$ in terms of the same gauge coupling constant $\alpha(H_0)$, which is fixed in our framework by recent BICEP2 measurements of the tensor fraction $r\simeq 0.2$.

Inflaton as an auxiliary topological field in a QCD-like system

We propose a new scenario for early cosmology, where inflationary de Sitter phase dynamically occurs. The effect emerges as a result of dynamics of the topologically nontrivial sectors in expanding universe. Technically the effect can be described in terms of the auxiliary fields which effectively describe the dynamics of the topological sectors in a gauge theory. Inflaton in this framework is an auxiliary topological non-propagating field with no canonical kinetic term, similar to known topologically ordered phases in condensed matter systems. We explain many deep questions in this framework using the so-called weakly coupled "deformed QCD" toy model.While this theory is weakly coupled gauge theory, it preserves all the crucial elements of strongly interacting gauge theory, including confinement, nontrivial $\theta$ dependence, degeneracy of the topological sectors, etc. We discuss a specific realization of these ideas using a scaled up version of QCD, coined as \qcd, with the scale M_{PL}\gg \Lbar\gg \sqrt[3]{M_{EW}^2M_{PL}}\sim 10^8 {\mathrm{GeV}}. If no other fields are present in the system de Sitter phase will be the final destination of evolution of the universe. If other interactions are present in the system, the inflationary de Sitter phase lasts for a finite period of time. The inflation starts from the thermal equilibrium state long after the \qcd -confinement phase transition at temperature T_{i}\sim \Lbar\sqrt{\frac{\Lbar}{M_{PL}}}. The end of inflation is triggered by the coupling with gauge bosons from the Standard Model. The corresponding interaction is unambiguously fixed by the triangle anomaly. Number of e-folds in the \qcd-inflation framework is determined by the gauge coupling constant at the moment of inflation, and estimated as N_{\rm inf}\sim \alpha_s^{-2}\sim 10^2.

An empirical investigation of the Taylor curve

Taylor (1979) posited that a central bank faces a tradeoff between the volatility of the output gap and volatility of inflation; this trade-off has become known as the Taylor curve. Thus, the Taylor curve necessitates that the correlation between the volatilities of inflation and the output gap be non-positive for optimal monetary policy. Friedman (2006) challenged Chatterjee (2002) and Taylor’s (2006) view that the Taylor curve may be used as a policy menu from which the central bank may choose the level of inflation and output gap volatilities. To better understand the issue, we take an in depth look at the correlation between the second moments of inflation and the output gap through the lens of the Taylor curve. Our results reveal that macroeconomic performance is superior in time periods in which the Taylor curve relationship holds.

Sticky Prices vs. Sticky Information - A Cross-Country Study of Inflation Dynamics

Dieses Papier liefert einen empirischen Vergleich der Sticky-Price- und Sticky-Information-Phillips-Kurven und betrachtet dazu die Inflationsdynamiken in sechs verschiedenen Landern (USA, Grosbritannien, Deutschland, Frankreich, Kanada und Japan). Wir werten die Fahigkeiten der Modelle aus, empirische zweite Momente des Inflationsprozesses zu generieren. Bei Benutzung von Basiskalibrierungen schneiden die Modelle in beinahe allen Landern ahnlich ab. Unter Verwendung von geschatzten Modellversionen schneidet Sticky Information mit franzosischen Daten und Sticky Prices mit britischen und deutschen Daten besser ab. Im Allgemeinen zeigt sich, dass Sticky Prices unbedingte Inflationsmomente besser abbildet und Sticky Information erfolgreicher in Bezug auf die Beziehung zwischen Inflation und Nachfrage ist. Des Weiteren verschlechtern sich die Erklarungsgrade beider Modelle dort, wo die Inflationsdynamik substantiell von der der USA abweicht.

Dual long memory of inflation and test of the relationship between inflation and inflation uncertainty

This paper uses the ARFIMA-FIGARCH model to investigate the China’s monthly inflation rate from January 1983 to October 2005. It is found that both first moment and second moment of inflation have remarkable long memory, indicating the existence of long memory properties in both inflation level and inflation uncertainty. By the Granger-causality test on inflation rate and inflation uncertainty, it is shown that the inflation level affects the inflation uncertainty and so supports Friedman hypothesis. Therefore, as for policy maker, they should roundly concerns on long memory properties of inflation and inflation uncertainty, and their single-direction relationship between them.

EMG of pharyngoesophageal musculature during alaryngeal voice production.

EMG activity from the inferior constrictor and cricopharyngeus muscles and the voice signal were obtained from 18 laryngectomized male subjects as they produced isolated vowels using alaryngeal phonation. To inflate the esophagus prior to phonation, all subjects but one demonstrated a similar muscle pattern: either one or both muscles studied showed a burst of activity at the moment of inflation. The remaining subject had a muscle pattern during inflation that was identical to a post-laryngectomy swallowing pattern. No typical or modal muscle patterns were found for subjects during the phonatory portion of the alaryngeal voice task. Consistency of pattern within each subject was extremely high during a given procedure and on repeated procedures. The findings suggested that poor talkers had less control of differential muscle contraction than did the adequate talkers and that each laryngectomized talker adopts a phonatory method that is unique to him and consistent with his postoperative anatomy and physiology.