Search for direct third-generation squark pair production in final states with missing transverse momentum and two b-jets in sqrts = 8 TeV pp collisions with the ATLAS detector

The results of a search for pair production of supersymmetric partners of the Standard Model third-generation quarks are reported. This search uses 20.1 fb(-1) of pp collisions at root s = 8 TeV collected by the ATLAS experiment at the Large Hadron Collider. The lightest bottom and top squarks ((b) over tilde (1) and (t) over tilde (1) respectively) are searched for in a final state with large missing transverse momentum and two jets identified as originating from b-quarks. No excess of events above the expected level of Standard Model background is found. The results are used to set upper limits on the visible cross section for processes beyond the Standard Model. Exclusion limits at the 95% confidence level on the masses of the third-generation squarks are derived in phenomenological supersymmetric R-parity-conserving models in which either the bottom or the top squark is the lightest squark. The (b) over tilde (1) is assumed to decay via (b) over tilde (1) -> b (chi) over tilde (0)(1) and the (t) over tilde (1) via (t) over tilde (1) b (chi) over tilde (+/-)(1), with undetectable products of the subsequent decay of the (chi) over tilde (+/-)(1) due to the small mass splitting between the (chi) over tilde (+/-)(1) and the (chi) over tilde (0)(1)

Search for third generation scalar leptoquarks in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

A search for pair-produced third generation scalar leptoquarks is presented, using proton-proton collisions at root s = 7 TeV at the LHC. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 4.7 fb(-1). Each leptoquark is assumed to decay to a tau lepton and a b-quark with a branching fraction equal to 100%. No statistically significant excess above the Standard Model expectation is observed. Third generation leptoquarks are therefore excluded at 95% confidence level for masses less than 534 GeV.

Service Level Agreements-Driven Management of Distributed Applications in Cloud Computing Environments

Cloud Computing enables provisioning and distribution of highly scalable services in a reliable, on-demand and sustainable manner. However, objectives of managing enterprise distributed applications in cloud environments under Service Level Agreement (SLA) constraints lead to challenges for maintaining optimal resource control. Furthermore, conflicting objectives in management of cloud infrastructure and distributed applications might lead to violations of SLAs and inefficient use of hardware and software resources. This dissertation focusses on how SLAs can be used as an input to the cloud management system, increasing the efficiency of allocating resources, as well as that of infrastructure scaling. First, we present an extended SLA semantic model for modelling complex service-dependencies in distributed applications, and for enabling automated cloud infrastructure management operations. Second, we describe a multi-objective VM allocation algorithm for optimised resource allocation in infrastructure clouds. Third, we describe a method of discovering relations between the performance indicators of services belonging to distributed applications and then using these relations for building scaling rules that a CMS can use for automated management of VMs. Fourth, we introduce two novel VM-scaling algorithms, which optimally scale systems composed of VMs, based on given SLA performance constraints. All presented research works were implemented and tested using enterprise distributed applications.

Search for pair-produced third-generation squarks decaying via charm quarks or in compressed supersymmetric scenarios in pp collisions at √s=8 TeV with the ATLAS detector

Results of a search for supersymmetry via direct production of third-generation squarks are reported, using 20.3  fb −1 of proton-proton collision data at √s =8  TeV recorded by the ATLAS experiment at the LHC in 2012. Two different analysis strategies based on monojetlike and c -tagged event selections are carried out to optimize the sensitivity for direct top squark-pair production in the decay channel to a charm quark and the lightest neutralino (t 1 →c+χ ˜ 0 1 ) across the top squark–neutralino mass parameter space. No excess above the Standard Model background expectation is observed. The results are interpreted in the context of direct pair production of top squarks and presented in terms of exclusion limits in the m ˜t 1, m ˜ X0 1 ) parameter space. A top squark of mass up to about 240 GeV is excluded at 95% confidence level for arbitrary neutralino masses, within the kinematic boundaries. Top squark masses up to 270 GeV are excluded for a neutralino mass of 200 GeV. In a scenario where the top squark and the lightest neutralino are nearly degenerate in mass, top squark masses up to 260 GeV are excluded. The results from the monojetlike analysis are also interpreted in terms of compressed scenarios for top squark-pair production in the decay channel t ˜ 1 →b+ff ′ +χ ˜ 0 1 and sbottom pair production with b ˜ 1 →b+χ ˜ 0 1 , leading to a similar exclusion for nearly mass-degenerate third-generation squarks and the lightest neutralino. The results in this paper significantly extend previous results at colliders.

Long-term Success of Family Firms: Investigating Specific Aspects of Firm-level Entrepreneurship and Individual-level Antecedents

Long-term success of family firms is of utmost social and economic importance. Three of its determinants are in the center of this Dissertation: firmlevel entrepreneurial orientation (EO), managers' entrepreneurial behavior, and value-creating attitudes of non-family employees. Each determinant and respective research gaps are addressed by one paper of this cumulative dissertation. Referring to firm-level EO, scholars claim that EO is a main antecedent to firms' both short- and long-term success. However, family firms seem to be successful across generations despite rather low levels of EO. The first paper addresses this paradox by investigating EO patterns of long-lived family firms in three Swiss case studies. The main finding is that the key to success is not to be as entrepreneurially as possible all the time, but to continuously adapt the EO profile depending on internal and external factors. Moreover, the paper suggest new subcategories to different EO dimensions. With regard to entrepreneurial behavior of managers, there is a lack of knowledge how individual-level and organizational level factors affect its evolvement. The second paper addresses this gap by investigating a sample of 403 middle-level managers from both family and non-family firms. It introduces psychological ownership of managers as individual-level antecedent and investigates the interaction with organizational factors. As a central insight, management support is found to strengthen the psychological ownership-entrepreneurial behavior relationship. The third paper is based on the fact that employees' justice perceptions are established antecedents of value-creating employee attitudes such as affective commitment and job satisfaction. Even though family firms are susceptible to nonfamily employees´ perceptions of injustice, corresponding research is scarce. Moreover, the mechanism connecting justice perceptions and positive outcomes is still unclear. Addressing these gaps, the analysis of a sample of 310 non-family employees reveals that psychological ownership is a mediator in the relationships between distributive justice perceptions and both affective commitment and job satisfaction. Altogether, the three papers offer valuable contributions to family business literature with respect to EO, entrepreneurial behavior, and value-creating employee attitudes. Thus, they increase current understanding about important determinants of family firms' long-term success, while opening up numerous ways of future research.