QCD next-to-leading-order predictions matched to parton showers for vector-like quark models

Vector-like quarks are featured by a wealth of beyond the Standard Model theories and are consequently an important goal of many LHC searches for new physics. Those searches, as well as most related phenomenological studies, however rely on predictions evaluated at the leading-order accuracy in QCD and consider well-defined simplified benchmark scenarios. Adopting an effective bottom-up approach, we compute next-to-leading-order predictions for vector-like-quark pair-production and single production in association with jets, with a weak or with a Higgs boson in a general new physics setup. We additionally compute vector-like-quark contributions to the production of a pair of Standard Model bosons at the same level of accuracy. For all processes under consideration, we focus both on total cross sections and on differential distributions, most these calculations being performed for the first time in our field. As a result, our work paves the way to precise extraction of experimental limits on vector-like quarks thanks to an accurate control of the shapes of the relevant observables and emphasize the extra handles that could be provided by novel vector-like-quark probes never envisaged so farComment: 21 pages, 12 figures, 6 tables; model files available from http://feynrules.irmp.ucl.ac.be/wiki/NLOModels; version accepted by EPJ

Efficiency Gains from the Relative Size of Information Technology Investments

The contribution of information technology (IT) to organizational performance has been investigated extensively in the MIS research recently. In this paper, the relationship between the relative size of IT investments by firms and the productive efficiency is examined using stochastic frontiers. We find evidence that the level of IT investments has a positive effect on the firm’s productive efficiency, implying that the firms investing relatively more in IT are likely to be more efficient in their production processes than those that invest less

Using Divide-and-Conquer to Solve the Multiple Discrete Resource Allocation Problem

The multiple discrete resource allocation problem (MDRAP) explores how the decision maker allocates a number of resources of different types among agents in order to achieve the aggregate maximum utility. The MDRAP belongs in the NP-hard category of time complexity, which requires excessive efforts to obtain the optimal solution even for a moderate problem size. Partial enumeration techniques such as dynamic programming and branch-and-bound are available to tackle this complexity issue to some degree. In this paper, a new partial enumeration method based on divide-and-conquer is proposed. The pronounced distinction of this divide-and-conquer approach lies in its potential ability to parallelize the solving process, and hence can obtain the optimal solution more quickly. A simulation study on a dedicated computer is conducted and presented

Bringing closure to microlensing mass measurement

Interferometers offer multiple methods for studying microlensing events and determining the properties of the lenses. We investigate the study of microlensing events with optical interferometers, focusing on narrow-angle astrometry, visibility, and closure phase. After introducing the basics of microlensing and interferometry, we derive expressions for the signals in each of these three channels. For various forecasts of the instrumental performance, we discuss which method provides the best means of measuring the lens angular Einstein radius theta_E, a prerequisite for determining the lens mass. If the upcoming generation of large-aperture, AO-corrected long baseline interferometers (e.g. VLTI, Keck, OHANA) perform as well as expected, theta_E may be determined with signal-to-noise greater than 10 for all bright events. We estimate that roughly a dozen events per year will be sufficiciently bright and have long enough durations to allow the measurement of the lens mass and distance from the ground. We also consider the prospects for a VLTI survey of all bright lensing events using a Fisher matrix analysis, and find that even without individual masses, interesting constraints may be placed on the bulge mass function, although large numbers of events would be required.Comment: 23 pages, aastex, submitted to Ap

A Model of Two-Zoned Networks for Platform-Mediated Markets: Theory and Practical Applications

Two-sided networks enabled by information technology (IT) represent an emerging type of platform-mediated market in the digital economy. Researchers have studied the associated economic and strategic issues from both theoretical and managerial perspectives; however, we have noticed inadequacy in the extant literature when observing some real-world cases that cannot be fully explained by the framework of two-sided networks. A more comprehensive model is needed to explicate the broader market structure and understand the underlying market dynamics. To achieve this aim, we propose a theoretical model of two-zoned networks. In extending the existing dimension of “side,” we add the “zone” dimension at a higher level to study two-zoned networks, which include two-sided networks as a special case. In the proposed model, two-zoned networks consist of two, two-sided networks and a core platform that serves both networks as their connection point at the nexus of two zones. Using the proposed model of two-zoned networks, we analyze four real-world business cases to demonstrate the model’s practical applications. Finally, strategic implications of this model, in terms of operational and legal ramifications, are described. We conclude with topics for future research

Relative Sizes of Information Technology Investments and Productive Efficiency: Their Linkage and Empirical Evidence

The contribution of information technology (IT) to organizational performance has been investigated extensively in recent IS research. A number of economic and financial measures have been employed by researchers to gauge the impact of IT on organizational performance. The results of previous research can be described as inconclusive at best. This paper uses stochastic frontiers to examine the relationship between the relative size of IT investments by firms and their productive efficiency in the production process. Assuming different production frontiers (including the popular generalized Cobb-Douglas, the more general Box-Cox transformation, and the most general Box-Tidwell transformation for the production process), we find consistent empirical evidence that the relative level of IT investments has a positive effect on the firm\u27s productive efficiency, implying that firms investing comparatively more in IT are likely to be more efficient in their production processes than those investing less. This study confirms the positive effect of IT on the firm\u27s efficiency in the production process, provides a source to explain the disappearance of the productivity paradox, and suggests a direction for future research that may integrate both economic and financial aspects of previous research on IT benefits