On the Suppression of Parametric Resonance and the Viability of Tachyonic Preheating after Multi-Field Inflation

We investigate the feasibility of explosive particle production via parametric resonance or tachyonic preheating in multi-field inflationary models by means of lattice simulations. We observe a strong suppression of resonances in the presence of four-leg interactions between the inflaton fields and a scalar matter field, leading to insufficient preheating when more than two inflatons couple to the same matter field. This suppression is caused by a dephasing of the inflatons that increases the effective mass of the matter field. Including three-leg interactions leads to tachyonic preheating, which is not suppressed by an increase in the number of fields. If four-leg interactions are sub-dominant, we observe a slight enhancement of tachyonic preheating. Thus, in order for preheating after multi-field inflation to be efficient, one needs to ensure that three-leg interactions are present. If no tachyonic contributions exist, we expect the old theory of reheating to be applicable.Comment: v2: reference added, identical with PRD version, 23 pages, 3 figure

CDO term structure modelling with Levy processes and the relation to market models

This paper considers the modelling of collateralized debt obligations (CDOs). We propose a top-down model via forward rates generalizing Filipovi\'c, Overbeck and Schmidt (2009) to the case where the forward rates are driven by a finite dimensional L\'evy process. The contribution of this work is twofold: we provide conditions for absence of arbitrage in this generalized framework. Furthermore, we study the relation to market models by embedding them in the forward rate framework in spirit of Brace, Gatarek and Musiela (1997).Comment: 16 page

Do Works Councils Inhibit Investment?

Theory suggests that firms confront a hold-up problem in dealing with workplace unionism: unions will appropriate a portion of the quasi rents stemming from long-lived capital. As a result, firms may be expected to limit their exposure to rent seeking by reducing investments, among other things. Although there is some empirical support for this prediction in firm-level studies for the United States, we investigate whether this is also the case in the different institutional context of Germany where the works council is the analogue of workplace unionism. Using parametric and nonparametric methods and establishment panel data, we find no evidence that the formation (dissolution) of a works council has an unfavorable (favorable) impact on investment. -- Theoretische Überlegungen deuten darauf hin, dass Firmen durch Arbeitnehmervertretungen auf Betriebsebene wie Gewerkschaften mit einem ?hold-up?-Problem konfrontiert werden, da letztere sich einen Teil der Quasi-Renten aus langlebigen Kapitalinvestitionen aneignen können. Deshalb mögen die Firmen ihre Anfälligkeit für derartiges ?rent seeking? dadurch verringern, dass sie ihre Investitionen zurückfahren. Während es für diese Hypothese empirische Bestätigungen durch Firmenstudien aus den USA gibt, untersuchen wir, ob dies auch in dem unterschiedlichen institutionellen Umfeld in Deutschland der Fall ist, wo statt Betriebsgewerkschaften Betriebsräte eine ähnliche Rolle spielen können. Unter Verwendung von parametrischen und nichtparametrischen Methoden sowie von Betriebspaneldaten finden wir keine empirischen Hinweise darauf, dass die Errichtung (bzw. Abschaffung) eines Betriebsrates einen negativen (bzw. positiven) Einfluss auf das betriebliche Investitionsverhalten hat.Investment,works councils,rent seeking,Germany,panel data

German works councils in the production process

We estimate the effects of works councils on productivity, 1997-2000, using the IAB Establishment Panel, a nationally representative German data set. We recoup the works council effect by estimating translog production functions, stochastic frontier production functions, and a model in first differences. Once we focus on a core sample of establishments with 21 to 100 employees in which the powers of the works council are a datum, it emerges that the positive productivity differential found in recent studies is a chimera. By the same token, neither is the works council effect negative. This result is important in its own right given the sharply opposing findings of past empirical research and the partisan positions these have helped sustain. -- Anhand des IAB-Betriebspanels, eines repräsentativen deutschen Firmendatensatzes, schätzen wir die Produktivitätswirkungen von Betriebsräten für den Zeitraum 1997-2000. Wir ermitteln den Betriebsratseffekt durch Schätzung von Translog-Produktionsfunktionen und Modellen in ersten Differenzen sowie durch stochastische Produktionsrandschätzungen. Wenn wir uns auf eine Kernstichprobe von Betrieben mit 21 bis 100 Beschäftigten konzentrieren, innerhalb derer die Rechte des Betriebsrats sich nicht ändern, erweist sich das in jüngeren Studien gefundene positive Produktivitätsdifferenzial als Chimäre. Allerdings fällt der Betriebsratseffekt auch nicht negativ aus. Diese Erkenntnis ist angesichts der extrem gegensätzlichen Ergebnisse früherer Studien und der darauf aufbauenden konträren Positionen besonders wichtig.Works council,production functions,panel data,Germany

Works Councils, Labor Productivity and Plant Heterogeneity: First Evidence from Quantile Regressions

Using OLS and quantile regression methods and rich cross-section data sets for western and eastern Germany, this paper demonstrates that the impact of works council presence on labor productivity varies between manufacturing and services, between plants that are or are not covered by collective bargaining, and along the conditional distribution of labor productivity. No productivity effects of works councils are found for the service sector and in manufacturing plants not covered by collective bargaining. Besides demonstrating that it is important to look at evidence based on more than one data set, our empirical findings point to the efficacy of supplementing OLS with quantile regression estimates when investigating the behavior of heterogeneous plants.Labor productivity, works councils, quantile regressions, heterogeneous firms

On the current practice of New Business Development in the German chemical industry

The results of a survey on the practice of new business development conducted in 17 chemical industry companies and related business sectors, such as service providers, are presented in this article. The objectives and organizational setup of New Business Development were found to be exceptionally heterogeneous and to cover a broad spectrum. The differentiation between New Business Development and Innovation Management was also not consistent between the companies. All the companies underlined the importance of technical and scientific know-how for new business development staff, but also emphasized the relevance of interdisciplinary competencies at the interface between natural science and business. Small companies follow a rather opportunistic New Business Development approach without dedicated organizational structures. Larger companies, on the other hand, employ a Stage-Gate process and largely derive their ideas from megatrends. Differences between small and larger companies are discussed in the article at hand