A new formulation of Lee-Wick quantum field theory

The Lee-Wick models are higher-derivative theories that are claimed to be unitary thanks to a peculiar cancelation mechanism. In this paper, we provide a new formulation of the models, to clarify several aspects that have remained quite mysterious, so far. Specifically, we define them as nonanalytically Wick rotated Euclidean theories. The complex energy plane is divided into disconnected regions, which can be related to one another by a well-defined, albeit nonanalytic procedure. Working in a generic Lorentz frame, the models are intrinsically equipped with the right recipe to treat the pinchings of the Lee-Wick poles, with no need of external ad hoc prescriptions. We describe these features in detail by calculating the one-loop bubble diagram and explaining how the key properties generalize to more complicated diagrams. The physical results of our formulation are different from those of the previous ones. The unusual behaviors of the physical amplitudes lead to interesting phenomenological predictions.Comment: 27 pages, 17 figures; v2: details about Lorentz invariance above LW thresholds; v3: minor changes, JHE

The skill bias in Italy: a first report

In this study three possible determinants of the increased demand for skilled workers are tested using a panel of 412 Italian manufacturing firms over the period 1989-1997. The results suggest the statistical significance of the impact of organisational change, while they tend to exclude the roles of R&D spending and foreign direct investment.

Finite quantum gauge theories

We explicitly compute the one-loop exact beta function for a nonlocal extension of the standard gauge theory, in particular Yang-Mills and QED. The theory, made of a weakly nonlocal kinetic term and a local potential of the gauge field, is unitary (ghost-free) and perturbatively super-renormalizable. Moreover, in the action we can always choose the potential (consisting of one "killer operator") to make zero the beta function of running gauge coupling constant. The outcome is "a UV finite theory for any gauge interaction". Our calculations are done in D=4, but the results can be generalized to even or odd spacetime dimensions. We compute the contribution to the beta function from two different killer operators by using two independent techniques, namely the Feynman diagrams and the Barvinsky-Vilkovisky traces. By making the theories finite we are able to solve also the Landau pole problems, in particular in QED. Without any potential the beta function of the one-loop super-renormalizable theory shows a universal Landau pole in the running coupling constant in the ultraviolet regime (UV), regardless of the specific higher-derivative structure. However, the dressed propagator shows neither the Landau pole in the UV, nor the singularities in the infrared regime (IR).Comment: 6 pages. arXiv admin note: text overlap with arXiv:1503.0026

Perturbative unitarity of Lee-Wick quantum field theory

We study the perturbative unitarity of the Lee-Wick models, formulated as nonanalytically Wick rotated Euclidean theories. The complex energy plane is divided into disconnected regions and the values of a loop integral in the various regions are related to one another by a nonanalytic procedure. We show that the one-loop diagrams satisfy the expected, unitary cutting equations in each region: only the physical degrees of freedom propagate through the cuts. The goal can be achieved by working in suitable subsets of each region and proving that the cutting equations can be analytically continued as a whole. We make explicit calculations in the cases of the bubble and triangle diagrams and address the generality of our approach. We also show that the same higher-derivative models violate unitarity if they are formulated directly in Minkowski spacetime.Comment: 30 pages, 15 figures; v2: more details and comments on generality of approach; v3: minor changes, PR

The Transatlantic Productivity Gap: Is R&D the Main Culprit?

The literature has pointed to different causes to explain the productivity gap between Europe and United States in the last decades. This paper tests the hypothesis that the lower European productivity performance in comparison with the US can be explained not only by a lower level of corporate R&D investment, but also by a lower capacity to translate R&D investment into productivity gains. The proposed microeconometric estimates are based on a unique longitudinal database covering the period 1990-2008 and comprising 1,809 US and European companies for a total of 16,079 observations. Consistent with previous literature, we find robust evidence of a significant impact of R&D on productivity; however – using different estimation techniques – the R&D coefficients for the US firms always turn out to be significantly higher. To see to what extent these transatlantic differences may be related to the different sectoral structures in the US and the EU, we differentiated the analysis by sectors. The result is that both in manufacturing, services and high-tech sectors US firms are more efficient in translating their R&D investments into productivity increases.R&D, productivity, embodied technological change, US, EU

R&D Expenditures and Employment: Evidence from Europe

Using a unique firm-level database comprising the top European R&D investors over the period 2002-2013 and running LSDVC estimates, this study finds a significant labourfriendly impact of R&D expenditures. However, this positive employment effect appears limited in magnitude and entirely due to the medium-and high-tech sectors, while no effect can be detected in the low-tech industries. From a policy point of view, this outcome is supporting the EU2020 strategy, but - taking into account that most of European economies are specialized in low-tech activities - is also worrying in terms of future perspectives of the European labour market

Technological Change and Employment: Were Ricardo and Marx Right?

The aim of this paper is twofold. On the one hand, the economic insights about the employment impact of technological change are disentangled starting from the classical economists to nowadays theoretical and empirical analyses. On the other hand, an empirical test is provided; in particular, longitudinal data covering manufacturing and service sectors over the 1998-2011 period for 11 European countries are used to run GMM-SYS and LSDVC estimates. Two are the main results: 1) a significant labour-friendly impact of R&D expenditures (mainly related to product innovation) is found; yet, this positive employment effect appears to be entirely due to the medium-and high-tech sectors, while no effect can be detected in the low-tech industries; 2) capital formation is found to be negatively related to employment; this outcome points to a possible labour-saving effect due to the embodied technological change incorporated in gross investment (mainly related to process innovation)

R&D and Employment: Some Evidence from European Microdata

After discussing theory regarding the consequences of technological change on employment and surveying previous microeconometric literature, our aim with this paper is to test the possible job creation effect of business R&D expenditures, using a unique longitudinal database covering 677 European manufacturing and service firms over the period 1990-2008. The main outcome from the whole sample dynamic LSDVC (Least Squared Dummy Variable Corrected) estimate is the labour-friendly nature of companies’ R&D, the coefficient of which turns out to be statistically significant, although not very large in magnitude. However, the positive and significant impact of R&D expenditures on employment is detectable in services and high-tech manufacturing but absent in the more traditional manufacturing sectors. This means that we should not expect positive employment effects from increasing R&D in the majority of industrial sectors. This is something that should be borne in mind by European innovation policy makers having employment as one of their specific aims.manufacturing, employment, innovation, services, LSDVC

How Do Young Innovative Companies Innovate?

This paper discusses the determinants of product innovation in young innovative companies (YICs) by looking at in-house and external R&D and at the acquisition of external technology in embodied and disembodied components. These input-output relationships are tested on a sample of innovative Italian firms. A sample-selection approach is applied. Results show that in-house R&D is linked to the propensity to introduce product innovation both in mature firms and YICs; however, innovation intensity in the YICs is mainly dependent on embodied technical change from external sources, while − in contrast with the incumbent firms − in-house R&D does not play a significant role.R&D, product innovation, embodied technical change, CIS 3, sample selection