PHOTOS as a pocket parton shower: flexibility tests for the algorithm

In this note we will recall the main tests that document robustness and flexibility of the PHOTOS design. This aspect may be of broader use and may find extensions in future applications, also outside the simple case of purely QED bremsstrahlung in decays. The components of the PHOTOS algorithm will be presented using operator language. The results of some flexibility tests, not documented before, will also be presented

Modeling large Ethernet networks for the ATLAS high level trigger system using parameterized models of switches and nodes

Large local area Ethernet networks are strong candidates to connect data sources and processing nodes in high energy physics experiments. In the high level trigger system of the ATLAS LHC experiment several Gbytes/s of data, distributed over 1700 buffers, have to be delivered to around a thousand processing nodes. Due to the network size, its performance and scalability can only be assessed by modeling. To avoid lengthy simulation runs, and concentrate only on characteristics important for network transfers, the components of the system need to be parameterized. The network performance depends on traffic patterns generated by processing nodes and switching capabilities of the network, we therefore evaluated and modeled both processing nodes and switches. We have developed a parameterized model of a class of switches, where a limited set of parameters, collected from measurements on real devices, is used to model switching characteristics. Another set of simple measurements is used to collect values for parameters used to model processing nodes running the Linux operating system and the TCP/IP communications protocol suite. In this paper we present the set of parameters used in the models together with measuring procedures used to calibrate our models. Calibrated models are used to model small test-bed setups with random traffic to validate our approach

CP violation in B0_d --> tau+ tau- decays

Establishing CP violation in B0 (bar{B0}) --> l+ l- decays requires a measurement of polarization of the final lepton pair, or a precise determination of the B0 --> l+ l- and bar{B0} --> l+ l- rates. We first argue that if the amplitudes of these decays are dominated by the scalar and pseudoscalar Higgs penguin diagrams, as happens e.g. in supersymmetry with large tan(beta), the CP asymmetries depend practically on only one CP violating phase. This phase can be large, of the order of the CKM phase, leading to large CP asymmetries in the tau+ tau- decay channel of B0_d (bar{B0}_d) mesons, potentially measurable in BELLE or BABAR experiments. Secondly, we show that the existing TAUOLA tau-lepton decay library supplemented by its universal interface can efficiently be used to search for B0 (bar{B0}) --> tau+ tau- decays, and to investigate how the CP asymmetry is reflected in realistic experimental observables.Comment: 1+20 pages, 5 figures, LaTe

Studies in Law. Research Papers

Słowo wstępne: "Drodzy Czytelnicy, Prezentujemy Państwu kolejny numer naszego periodyku. W tym bogatym zbiorze wypowiedzi przedstawicieli doktryny prawa i praktyki prawniczej znalazło się miejsce dla prac autorów z różnych dziedzin prawa. Analizowane zagadnienia odnoszą się w szczególności do problematyki prawa konstytucyjnego, prawa cywilnego, prawa pracy, prawa karnego. Zgromadziliśmy cenne spostrzeżenia autorów z różnych ośrodków akademickich – tak z Polski, jak i z zagranicy. Obok interesujących artykułów naukowych oraz glos przedstawiamy też niemałą liczbę innych tekstów, przede wszystkim recenzji publikacji naukowych i sprawozdań pokonferencyjnych. Mamy nadzieję, że ten, jak i przyszłe numery czasopisma stanowić będą dla Państwa interesującą lekturę, skłaniającą do refleksji nad poruszanymi tematami i prowokującą do tworzenia kolejnych prac naukowych. Liczymy, że zechcą Państwo publikować je – jak do tej pory – na łamach czasopisma „Studia Prawnicze. Rozprawy i Materiały”. Życzę inspirującej lektury!"(...

Securing Access to Controls Applications with Apache httpd Proxy

Many commercial systems used for controls nowadays contain embedded web servers. Secure access to these, often essential, facilities is of utmost importance, yet it remains complicated to manage for different reasons (e.g. obtaining and applying patches from vendors, ad-hoc oversimplified implementations of web-servers are prone to remote exploit). In this paper we describe a security-mediating proxy system, which is based on the well-known Apache httpd software. We describe how the use of the proxy made it possible to simplify the infrastructure necessary to start WinCC OA-based supervision applications on operator consoles, providing, at the same time, an improved level of security and traceability. Proper integration with the CERN central user account repository allows the operators to use their personal credentials to access applications, and also allows one to use standard user management tools. In addition, easy-to-memorize URL addresses for access to the applications are provided, and the use of a secure https transport protocol is possible for services that do not support it on their own

Consolidation and Redesign of CERN Industrial Controls Frameworks

The Industrial Controls Frameworks, JCOP and UNICOS, have been employed to develop hundreds of critical controls applications in multiple domains like the detector control system, accelerator complex (cryogenics, powering, interlocks) or technical infrastructure, leading to an unprecedented level of homogeneity. These frameworks, used by a thousand of developers worldwide, will now undergo a major consolidation and re-engineering effort to prepare them for the new challenges of the next 20 years in the HL-LHC era, and streamline their maintenance. The paper presents the challenges that will be faced during this project due to the breadth of technological stack and large code-base contributed over two decades by numerous authors. Delivery of innovation induced by evolution of technologies and refactoring of the ageing code must be done in a way that ensures backward-compatibility for existing systems. The vision and the current state of the frameworks is discussed, alongside the main deliveries planned in the medium term. Lessons learnt, optimizations of processes to make best use of available resources and efforts towards open-source licensing of the frameworks are also presented