Jet Function with a Jet Algorithm in SCET

The jet function for the factorized cross section $e^+e^-$ into dijets is given as a function of the jet invariant mass s and with a generic jet algorithm at $\mathcal{O}(\alpha_s)$. We demonstrate the results using the Sterman-Weinberg algorithm and show that the jet function is independent of the energy fraction $\beta$ of the soft radiation. The anomalous dimension has the same form with and without the cone half-angle $\delta$. The dependence of the finite part of the jet function on the cone angle is given.Comment: 10 pages, 5 figures, journal versio

On the role of shear in cosmological averaging

Using the spherically symmetric inhomogeneous Lemaitre-Tolman-Bondi dust solution, we study how the shear and the backreaction depend on the sharpness of the spatial transition between voids and walls and on the size of the voids. The voids considered here are regions with matter density Omega ~ 0 and expansion rate Ht ~ 1, while the walls are regions with matter density Omega ~ 1 and expansion rate Ht ~ 2/3. The results indicate that both the volume-average shear and the variance of the expansion rate grow proportional to the sharpness of the transition and diverge in the limit of a step function, but, for realistic-sized voids, are virtually independent of the size of the void. However, the backreaction, given by the difference of the variance and the shear, has a finite value in the step-function limit. By comparing the exact result for the backreaction to the case where the shear is neglected by treating the voids and walls as separate Friedmann-Robertson-Walker models, we find that the shear suppresses the backreaction by a factor of (r_0/t_0)^2, the squared ratio of the void size to the horizon size. This exemplifies the importance of using the exact solution for the interface between the regions of different expansion rates and densities. The suppression is justified to hold also for a network of compensated voids, but may not hold if the universe is dominated by uncompensated voids.Comment: 17 pages, 3 figure

Individuals and Organizations Thoughts on a Micro-Foundations Project for Strategic Management and Organizational Analysis

Making links between micro and macro levels has been problematic in the social sciences, and the literature in strategic management and organization theory is no exception. The purpose of this chapter is to raise theoretical issues in developing micro-foundations for strategic management and organizational analysis. We discuss more general problems with collectivism in the social sciences by focusing on specific problems in extant organizational analysis. We introduce micro-foundations to the literature by explicating the underlying theoretical foundations of the origins of individual action and interaction. We highlight opportunities for future research, specifically emphasizing the need for a rational choice program in management research.

Optimal Economic Growth Using Fiscal and Monetary Policies

The literature on growth theory is rich with models attempting to explain growth differences among countries. Several variables have been proposed many of which were found to be positively related to growth. However, a major problem with these models is that the factors explaining growth are endogenously determined by their environment so that a slow-growing or a poor country will find itself helpless because all the crucial variables it has `inherited' are either deficient or inexistent. We propose policyoriented model that empowers (poor or slow-growing) countries in the sense that they can use economic policies to achieve high growth and eliminate the gap of unused productive capacity of society. We demonstrate that such objectives are possible by manipulating some key control variables, namely the rate of interest and the net government spending.growth, maximization, fiscal policy, interest rates, deficit, money

Building Micro-Foundations for the Routines, Capabilities, and Performance Links

Micro-foundations have become an important emerging theme in strategic management. This paper addresses micro-foundations in two related ways. First, we argue that the kind of macro (or “collectivist”) explanation that is utilized in the capabilities view in strategic management ? which implies a neglect of micro-foundations ? is incomplete. There are no mechanisms that work solely on the macro-level, directly connecting routines and capabilities to firm-level outcomes. While routines and capabilities are useful shorthand for complicated patterns of individual action and interaction, ultimately they are best understood at the micro-level. Second, we provide a formal model that shows precisely why macro explanation is incomplete and which exemplifies how explicit micro-foundations may be built for notions of routines and capabilities and for how these impact firm performance.Routines, capabilities, micro-foundations, production function

Noiseless amplification of weak coherent fields without external energy

According to the fundamental laws of quantum optics, noise is necessarily added to the system when one tries to clone or amplify a quantum state. However, it has recently been shown that the quantum noise related to the operation of a linear phase-insensitive amplifier can be avoided when the requirement of a deterministic operation is relaxed. Nondeterministic noiseless linear amplifiers are therefore realizable. Usually nondeterministic amplifiers rely on using single photon sources. We have, in contrast, recently proposed an amplification scheme in which no external energy is added to the signal, but the energy required to amplify the signal originates from the stochastic fluctuations in the field itself. Applying our amplification scheme, we examine the amplifier gain and the success rate as well as the properties of the output states after successful and failed amplification processes. We also optimize the setup to find the maximum success rates in terms of the reflectivities of the beam splitters used in the setup. In addition, we discuss the nonidealities related to the operation of our setup and the relation of our setup with the previous setups.Comment: arXiv admin note: substantial text overlap with arXiv:1309.428

On the role of shear in cosmological averaging II: large voids, non-empty voids and a network of different voids

We study the effect of shear on the cosmological backreaction in the context of matching voids and walls together using the exact inhomogeneous Lemaitre-Tolman-Bondi solution. Generalizing JCAP 1010 (2010) 021, we allow the size of the voids to be arbitrary and the densities of the voids and walls to vary in the range 0 < Omega_v < Omega_w < 1. We derive the exact analytic result for the backreaction and consider its series expansion in powers of the ratio of the void size to the horizon size, r_0/t_0. In addition, we deduce a very simple fitting formula for the backreaction with error less than 1% for voids up to sizes r_0 = t_0. We also construct an exact solution for a network of voids with different sizes and densities, leading to a non-zero relative variance of the expansion rate between the voids. While the leading order term of the backreaction for a single void-wall pair is of order (r_0/t_0)^2, the relative variance between the different voids in the network is found to be of order (r_0/t_0)^4 and thus very small for voids of the observed size. Furthermore, we show that even for very large voids, the backreaction is suppressed by an order of magnitude relative to the estimate obtained by treating the walls and voids as disjoint Friedmann solutions. Whether the suppression of the backreaction due to the shear is just a consequence of the restrictions of the used exact models, or a generic feature, has to be addressed with more sophisticated solutions.Comment: 19 pages, 5 figure

Open geometry Fourier modal method: Modeling nanophotonic structures in infinite domains

We present an open geometry Fourier modal method based on a new combination of open boundary conditions and an efficient $k$-space discretization. The open boundary of the computational domain is obtained using basis functions that expand the whole space, and the integrals subsequently appearing due to the continuous nature of the radiation modes are handled using a discretization based on non-uniform sampling of the $k$-space. We apply the method to a variety of photonic structures and demonstrate that our method leads to significantly improved convergence with respect to the number of degrees of freedom, which may pave the way for more accurate and efficient modeling of open nanophotonic structures