Endogenously-Timed Herding And The Synchronization Of Investment Cycles

This paper combines the recent garne theoretic approach of endogenous timing of entry to herding models with a rnacroeconornic model of investrnent cycles. The integrated description embodies the qualitative resuits of the rnyopic herding model in a medium run investment objective of smooth ing the capital stock adjustment process. lt features a completely disaggregated structure and bears the potential to synchronize individual cyclic investing be haviors. This synchronization via nonlinear feedback from the aggregate ac tivity can serve as an explanation of the inexistent cancelling of heterogeneous sectoral quasi-cycles. The model others an explanatory base for the constitu tion of the observed strong cyclicality of the aggregate investment series by a multitude of different periodicities and phases on the individual level. Finally, based on recent ndings of the herding literature, the stabilization potential of third parties' information revelation is conjectured

On the structure of two-point Green-functions at next-to-leading order in 1/Nc

The structure of the two-point QCD Green-functions is studied in this note in the limit of large number of colours. Their general form at next-to-leading order in 1/Nc is derived keeping the infinite resonance summation and without relying on a particular realization of the hadronic action. It is found that the contributions from chiral operators without resonance fields of order p^4 or higher are irrelevant for the computation of the correlators and, hence, they can be dropped at the beginning of the calculation. The possibility of a more general cancelation of these local terms at the level of the generating functional is discussed.Comment: 6 pages, 1 figur

How does an interacting many-body system tunnel through a potential barrier to open space?

The tunneling process in a many-body system is a phenomenon which lies at the very heart of quantum mechanics. It appears in nature in the form of alpha-decay, fusion and fission in nuclear physics, photoassociation and photodissociation in biology and chemistry. A detailed theoretical description of the decay process in these systems is a very cumbersome problem, either because of very complicated or even unknown interparticle interactions or due to a large number of constitutent particles. In this work, we theoretically study the phenomenon of quantum many-body tunneling in a more transparent and controllable physical system, in an ultracold atomic gas. We analyze a full, numerically exact many-body solution of the Schr\"odinger equation of a one-dimensional system with repulsive interactions tunneling to open space. We show how the emitted particles dissociate or fragment from the trapped and coherent source of bosons: the overall many-particle decay process is a quantum interference of single-particle tunneling processes emerging from sources with different particle numbers taking place simultaneously. The close relation to atom lasers and ionization processes allows us to unveil the great relevance of many-body correlations between the emitted and trapped fractions of the wavefunction in the respective processes.Comment: 18 pages, 4 figures (7 pages, 2 figures supplementary information