Studies of the internal properties of jets and jet substructure with the ATLAS Detector

The internal structure of jets produced in pp collisions at the LHC is measured using the ATLAS detector in an inclusive jet sample corresponding to 35pb-1 of pp collisions at sqrt(s) = 7 TeV. Classical jet shape and energy flow measurements are complemented with measurements of new substructure observables with comparisons made to several leading order parton shower Monte Carlo programs. The jet invariant mass and \kt splitting scale are measured for anti-kt jets with a distance parameter of R=1.0 and Cambridge-Aachen jets with R=1.2. Furthermore, a splitting and filtering procedure is applied to the Cambridge-Aachen jets. These tools are then utilized for the first measurements of the filtered jet mass at the LHC in the inclusive jet sample as well the W+1 jet sample, in which a hadronic W mass peak is observed in the jet invariant mass spectrum. A sample of candidate boosted top quark events is also analyzed in detail for the jet substructure properties of hadronic "top-jets" in the final state.Comment: Proceedings of the EPS-HEP 2011 Conference, 21 - 27 July 2011, Grenoble, Rhone-Alpes, Franc

The MODE family of facility class experiments

The objective of the Middeck 0-gravity Dynamics Experiment (MODE) is to characterize fundamental 0-g slosh behavior and obtain quantitative data on slosh force and spacecraft response for correlation of the analytical model. The topics are presented in viewgraph form and include the following: space results; STA objectives, requirements, and approach; comparison of ground to orbital data for the baseline configuration; conclusions of orbital testing; flight experiment resources; Middeck Active Control Experiment (MACE); MACE 1-G and 0-G models; and future efforts

Robust Bayesian inference via coarsening

The standard approach to Bayesian inference is based on the assumption that the distribution of the data belongs to the chosen model class. However, even a small violation of this assumption can have a large impact on the outcome of a Bayesian procedure. We introduce a simple, coherent approach to Bayesian inference that improves robustness to perturbations from the model: rather than condition on the data exactly, one conditions on a neighborhood of the empirical distribution. When using neighborhoods based on relative entropy estimates, the resulting "coarsened" posterior can be approximated by simply tempering the likelihood---that is, by raising it to a fractional power---thus, inference is often easily implemented with standard methods, and one can even obtain analytical solutions when using conjugate priors. Some theoretical properties are derived, and we illustrate the approach with real and simulated data, using mixture models, autoregressive models of unknown order, and variable selection in linear regression

Submission to standards committee consultation on lobbying the Scottish Parliament, 28 February

The Stirling Media Research Institute has been engaged in an ongoing programme of research into the public relations and lobbying industry in Scotland, the UK and Europe since 1996 . We have been encouraged by the Standards Committee's recognition of the importance of lobbying as a matter of both professional and public concern, and we welcome the opportunity to respond to the consultation paper. Our contribution is offered in the spirit of independent academic analysis. We have monitored the growth and development of the lobbying industry in Scotland and interviewed a wide range of lobbyists and public relations professionals ranging across the commercial (consultancy and in-house) and voluntary sectors. As part of our research activity, the SMRI has been a corporate member of ASPA since its inception. When we joined, it was made clear we were researchers and not in any way engaged in professional lobbying. Our research at the UK and European levels has also brought us into contact with commercial and voluntary sector lobbyists who work in other jurisdictions, and has broadened our perspective on the issues relating to lobbying

MIT Space Engineering Research Center

The Space Engineering Research Center (SERC) at MIT, started in Jul. 1988, has completed two years of research. The Center is approaching the operational phase of its first testbed, is midway through the construction of a second testbed, and is in the design phase of a third. We presently have seven participating faculty, four participating staff members, ten graduate students, and numerous undergraduates. This report reviews the testbed programs, individual graduate research, other SERC activities not funded by the Center, interaction with non-MIT organizations, and SERC milestones. Published papers made possible by SERC funding are included at the end of the report

Physical insight into the simultaneous optimization of structure and control

Recent trends in spacecraft design which yield larger structures with more stringent performance requirements place many flexible modes of the structure within the bandwidth of active controllers. The resulting complications to the spacecraft design make it highly desirable to understand the impact of structural changes on an optimally controlled structure. This work uses low structural models with optimal H(sub 2) and H(sub infinity) controllers to develop some basic insight into this problem. This insight concentrates on several basic approaches to improving controlled performance and how these approaches interact in determining the optimal designs. A numerical example is presented to demonstrate how this insight can be generalized to more complex problems

Particle-level pileup subtraction for jets and jet shapes

We present an extension to the jet area-based pileup subtraction for both jet kinematics and jet shapes. A particle-level approach is explored whereby the jet constituents are corrected or removed using an extension of the methods currently being employed by the LHC experiments. Several jet shapes and nominal jet radii are used to assess the performance in simulated events with pileup levels equivalent to approximately 30 and 100 interactions per bunch crossing, which are characteristic of both the LHC Run I and Run II conditions. An improved performance in removing the pileup contributions is found when using the new subtraction method. The performance of the new procedure is also compared to other existing methods

Middeck Active Control Experiment (MACE), phase A

A rationale to determine which structural experiments are sufficient to verify the design of structures employing Controlled Structures Technology was derived. A survey of proposed NASA missions was undertaken to identify candidate test articles for use in the Middeck Active Control Experiment (MACE). The survey revealed that potential test articles could be classified into one of three roles: development, demonstration, and qualification, depending on the maturity of the technology and the mission the structure must fulfill. A set of criteria was derived that allowed determination of which role a potential test article must fulfill. A review of the capabilities and limitations of the STS middeck was conducted. A reference design for the MACE test article was presented. Computing requirements for running typical closed-loop controllers was determined, and various computer configurations were studied. The various components required to manufacture the structure were identified. A management plan was established for the remainder of the program experiment development, flight and ground systems development, and integration to the carrier. Procedures for configuration control, fiscal control, and safety, reliabilty, and quality assurance were developed

Jet substructure in ATLAS

Measurements are presented of the jet invariant mass and substructure in proton-proton collisions at sqrt{s} = 7 TeV with the ATLAS detector using an integrated luminosity of 37 pb-1. These results exercise the tools for distinguishing the signatures of new boosted massive particles in the hadronic final state. Two "fat" jet algorithms are used, along with the filtering jet grooming technique that was pioneered in ATLAS. New jet substructure observables are compared for the first time to data at the LHC. Finally, a sample of candidate boosted top quark events collected in the 2010 data is analyzed in detail for the jet substructure properties of hadronic "top-jets" in the final state. These measurements demonstrate not only our excellent understanding of QCD in a new energy regime but open the path to using complex jet substructure observables in the search for new physics.Comment: Proceedings of the DPF-2011 Conference, Providence, RI, August 8-13, 201