J. Steggemann

The Visual Physics Analysis (VISPA) project integrates different aspects of physics analyses into a graphical development environment. It addresses the typical development cycle of (re-)designing, executing and verifying an analysis. The project provides an extendable plug-in mechanism and includes plug-ins for designing the analysis flow, for running the analysis on batch systems, and for browsing the data content. The corresponding plug-ins are based on an object-oriented toolkit for modular data analysis. We introduce the main concepts of the project, describe the technical realization and demonstrate the functionality in example applications.

Bachelor of physics lectures on 'Particle Physics and Astrophysics' were complemented by exercises related to data analysis and data interpretation at the RWTH Aachen University recently. The students performed these exercises using the internet platform VISPA, which provides a development environment for physics data analyses. We describe the platform and its application within the physics course, and present the results of a student survey. The students' acceptance of the learning project was positive. The level of acceptance was related to their individual preference for learning with a computer. Furthermore, students with good programming skills favour working individually, while students who attribute themselves as having low programming abilities favour working in teams. The students appreciated approaching actual research through the data analysis tasks.

Extended scalar sectors appear in various extensions of the Standard Model of particle physics, such as supersymmetric models. They are also generic extensions of the Standard Model and can address a number of its shortcomings. Direct searches for additional Higgs bosons and measurements of the 125-GeV Higgs boson, both of which provide insights into the different possible sectors, are carried out at the LHC. This review gives an overview of searches for the additional Higgs bosons and their implications for different models. The discussed analyses comprise searches for neutral and charged Higgs bosons that decay in various final states. In addition, the review summarizes the constraints from precision measurements, including in particular the observed couplings of the 125-GeV Higgs boson. While several models naturally incorporate a Higgs boson with couplings that are similar to the ones in the Standard Model, the measurements of the 125-GeV Higgs boson provide constraints on all considered extensions.

Visual Physics Analysis (VISPA) is a web-based development environment addressing high energy and astroparticle physics. It covers the entire analysis spectrum from the design and validation phase to the execution of analyses and the visualization of results. VISPA provides a graphical steering of the analysis flow, which consists of self-written, re-usable Python and C++ modules for more demanding tasks. All common operating systems are supported since a standard internet browser is the only software requirement for users. Even access via mobile and touch-compatible devices is possible. In this contribution, we present the most recent developments of our web application concerning technical, state-of-the-art approaches as well as practical experiences. One of the key features is the use of workspaces, i.e. user-configurable connections to remote machines supplying resources and local file access. Thereby, workspaces enable the management of data, computing resources (e.g. remote clusters or computing grids), and additional software either centralized or individually. We further report on the results of an application with more than 100 third-year students using VISPA for their regular particle physics exercises during the winter term 2012/13. Besides the ambition to support and simplify the development cycle of physics analyses, new use cases such as fast, location-independent status queries, the validation of results, and the ability to share analyses within worldwide collaborations with a single click become conceivable.

We present a procedure for reconstructing particle cascades from event data measured in a high energy physics experiment. For evaluating the hypothesis of a specific physics process causing the observed data, all possible reconstruction versions of the scattering process are constructed from the final state objects. We describe the procedure as well as examples of physics processes of different complexity studied at hadron-hadron colliders. We estimate the performance by 20 microseconds per reconstructed decay vertex, and 0.6 kByte per reconstructed particle in the decay trees.

VISPA is a development environment for high energy physics analyses which enables physicists to combine graphical and textual work. A physics analysis cycle consists of prototyping, performing, and verifying the analysis. The main feature of VISPA is a multipurpose window for visual steering of analysis steps, creation of analysis templates, and browsing physics event data at different steps of an analysis. VISPA follows an experiment-independent approach and incorporates various tools for steering and controlling required in a typical analysis. Connection to different frameworks of high energy physics experiments is achieved by using different types of interfaces. We present the look-and-feel for an example physics analysis at the LHC and explain the underlying software concepts of VISPA.

VISPA (Visual Physics Analysis) is a development environment to support physicists in prototyping, execution, and verification of data analysis of any complexity. The key idea of VISPA is to develop physics analyses using a combination of graphical and textual programming. In VISPA, a multipurpose window provides visual tools to design and execute modular analyses, create analysis templates, and browse physics event data at different steps of an analysis. VISPA aims at supporting both experiment independent and experiment specific analysis steps. It is therefore designed as a portable analysis framework for Linux, Windows and MacOS, with its own data format including physics objects and containers, thus allowing convenient transport of analyses between different computers. All components of VISPA are designed for straightforward integration with experiment specific software to enable physics analysis with the same graphical tools. VISPA has proven to be an easy-to-use and flexible development environment in high energy physics as well as in astroparticle physics analyses.

VISPA is a novel development environment for high energy physics analyses, based on a combination of graphical and textual steering. The primary aim of VISPA is to support physicists in prototyping, performing, and verifying a data analysis of any complexity. We present example screenshots, and describe the underlying software concepts.

The project VISPA@WEB provides a novel graphical development environment for physics analyses which only requires a standard web browser on the client machine. It resembles the existing analysis environment available from the project Visual Physics Analysis VISPA, including the connection and configuration of modules for different tasks. High level logic can be programmed using the Python language, while performance-critical tasks can be implemented in C++ modules. The use cases range from simple teaching examples to highly complex scientific analyses.

Many programs in experimental particle physics do not yet have a graphical interface, or demand strong platform and software requirements. With the most recent development of the VISPA project, we provide graphical interfaces to existing software programs and access to multiple computing clusters through standard web browsers. The scalable clientserver system allows analyses to be performed in sizable teams, and disburdens the individual physicist from installing and maintaining a software environment. The VISPA graphical interfaces are implemented in HTML, JavaScript and extensions to the Python webserver. The webserver uses SSH and RPC to access user data, code and processes on remote sites. As example applications we present graphical interfaces for steering the reconstruction framework OFFLINE of the Pierre-Auger experiment, and the analysis development toolkit PXL. The browser based VISPA system was field-tested in biweekly homework of a third year physics course by more than 100 students. We discuss the system deployment and the evaluation by the students.

The job configuration system of the CMS experiment is based on the Python programming language. Software modules and their order of execution are both represented by Python objects. In order to investigate and verify configuration parameters and dependencies naturally appearing in modular software, CMS employs a graphical tool. This tool visualizes the configuration objects, their dependencies, and the information flow. Furthermore it can be used for documentation purposes. The underlying software concepts as well as the visualization are presented.

Visual Physics Analysis (VISPA) is an analysis environment with applications in high energy and astroparticle physics. Based on a data-flow-driven paradigm, it allows users to combine graphical steering with self-written C++ and Python modules. This contribution presents new concepts integrated in VISPA: layers, convenient analysis execution, and web-based physics analysis. While the convenient execution offers full flexibility to vary settings for the execution phase of an analysis, layers allow to create different views of the analysis already during its design phase. Thus, one application of layers is to define different stages of an analysis (e.g. event selection and statistical analysis). However, there are other use cases such as to independently optimize settings for different types of input data in order to guide all data through the same analysis flow. The new execution feature makes job submission to local clusters as well as the LHC Computing Grid possible directly from VISPA. Web-based physics analysis is realized in the VISPA@Web project, which represents a whole new way to design and execute analyses via a standard web browser.

Searches for Higgs bosons decaying to lepton pairs are summarised using the run 1 dataset recorded by the CMS detector. The first part of this summary is devoted to the search for Higgs bosons decaying to tau pairs. The search is carried out using all six tau-pair final states, with the tau decaying to a muon, an electron, or hadrons. Evidence for Higgs boson decays to taus is reported, and constraints on the couplings of the Higgs boson to fermions and bosons are derived. Then, searches for Higgs boson decays to muons and electrons are also discussed. The last part discusses a search for lepton-flavour violating Higgs boson decays to a muon and a tau, with the tau being reconstructed in the decay to an electron or hadrons. The analysis places the best limits on the respective Yukawa couplings to date while showing a slight excess of 2.5 standard deviations above the standard model expectation.

The Visual Physics Analysis (VISPA) project provides a graphical development environment for data analysis. It addresses the typical development cycle of (re-)designing, executing, and verifying an analysis. We present the new server-client-based web application of the VISPA project to perform physics analyses via a standard internet browser. This enables individual scientists to work with a large variety of devices including touch screens, and teams of scientists to share, develop, and execute analyses on a server via the web interface.

VISPA (Visual Physics Analysis) is a development environment to support physicists in prototyping, execution, and verification of data analysis of any complexity.The key idea of VISPA is to develop physics analyses using a combination of graphical and textual programming.In VISPA, a multipurpose window provides visual tools to design and execute modular analyses, create analysis templates, and browse physics event data at different steps of an analysis.VISPA aims at supporting both experiment independent and experiment specific analysis steps.It is therefore designed as a portable analysis framework for Linux, Windows and MacOS, with its own data format including physics objects and containers, thus allowing convenient transport of analyses between different computers.All components of VISPA are designed for straightforward integration with experiment specific software to enable physics analysis with the same graphical tools.VISPA has proven to be an easy-to-use and flexible development environment in high energy physics as well as in astroparticle physics analyses.

The VISPA programm supports particle physicists and astroparticle physicists in their data analysis projects.VISPA combines elements off graphical and textual programming to enable fast development cycles of physics analyses.

VISPA is a novel development environment for high energy physics analyses, based on a combination of graphical and textual steering. The primary aim of VISPA is to support physicists in prototyping, performing, and verifying a data analysis of any complexity. We present example screenshots, and describe the underlying software concepts.

VISPA is a novel graphical development environment for physics analysis, following an experiment-independent approach.It introduces a new way of steering a physics data analysis, combining graphical and textual programming.The purpose is to speed up the design of an analysis, and to facilitate its control.As the software basis for VISPA the C++ toolkit Physics eXtension Library (PXL) is used which is a successor project of the Physics Analysis eXpert (PAX) package.The most prominent features of this toolkit are the management of relations, a copyable container holding different aspects of physics events, the ability to store arbitrary user data, and a fast I/O.In order to support modular physics analysis, VISPA provides a module handling system using the above mentioned event container as the interface.Several analysis modules are provided, e.g. a module for automated reconstruction of particle cascades.All modules can be steered through Python scripts.Physicists can easily write their own modules to the module handling system or extend the existing ones.In this paper the concept of VISPA will be presented.

We present an algorithm for reconstructing particle cascades from event data of a high energy physics experiment. For a given physics process, the algorithm reconstructs all possible configurations of the cascade from the final state objects. We describe the procedure as well as examples of physics processes of different complexity studied at hadron-hadron colliders. We estimate the performance of the algorithm by 20 microseconds per reconstructed decay vertex, and 0.6 kByte per reconstructed particle in the decay trees.