First results and status of the ATLAS detector at the LHC

The road with early ATLAS data towards top physics is discussed. This includes a detailed understanding of the detector performance for key components of top quark decays like jets, tracking and lepton identification as well as measurements on minimum bias and underlying event physics. The status of these studies based on the first tens of nb −1 is presented

Cuerpo glorioso y economía digital [a propósito de un libro de Jean-Luc Nancy]1

La aparición digital contempla la posibilidad de una inmanencia, es decir de un exceso, y a la vez, de una justicia. y no sólo de la fotografía analógica que padece una suerte de ensanchamiento de su horizonte comprensivosino de un cúmulo de datos externos, todos los cuales, ahora modificados, conforman una conciencia expandida y variopinta. Si la fotografía ha sido un campo en expansión, la era digital dilata aún más sus confines porque, sencillamente, todo puede formar parte de su economía. Alcanza la sensibilidad, el entendimiento y sus encarnaciones canónicas, sobre todo, confunde los órdenes. convoca una nueva lucidez, a veces embota, aturde, adormece. E irrumpe como modelo, como síntesis conectiva de las gramáticas más diversas. En este entendido, es posible que Jean-Luc Nancy, al momento de ver lo que tiene para decirnos el relato de Juan, no haga más que evocar la metamorfosis ya no del cuerpo, sino de aquella representación devenida convencional que se desglosa de la imagen por venir del Resucitado. El inventario de los ‹noli me tangere› no lo sabemos a ciencia cierta se prolongan más allá de sí mismos. no se trata de ningún mito sino de una teología que a recaudo de la escolástica medieval, vuelve sobre lo que pudo imaginar a medias la filosofía primera

A new method to determine the electroweak couplings of individual light flavours at LEP

A method is presented for determining the yields and properties of individual light quark flavours in $Z^0$ decays that is essentially free of detailed assumptions about hadronisation. The method uses an equation system with the number of events which are single and double tagged by high energy hadrons as inputs. In addition, SU(2) isospin symmetry and the flavour independence of QCD are used to derive general relations between hadron production from the various primary light quarks. Assuming the branching fractions $R_q$ of the $Z^0$ into down and strange quarks to be the same, five million hadronic $Z^0$ decays may allow a precisions of $\delta{(R_d=R_s)}/(R_d=R_s)\sim{0.05}$ and $\delta A_{FB}(d=s) \sim \delta A_{FB}(u) \sim{0.015}$ for the corresponding asymmetries. The method can be extended to include somewhat more model dependent symmetries of hadron production, which then allows the electroweak observables for each of the individual light quarks to be determined

Model Choice and Crucial Tests. On the Empirical Epistemology of the Higgs Discovery

Abstract: Our paper discusses the epistemic attitudes of particle physicists on the discovery of the Higgs boson at the Large Hadron Collider (LHC). It is based on questionnaires and interviews made shortly before and shortly after the discovery in 2012. We show, to begin with, that the discovery of a Standard Model (SM) Higgs boson was less expected than is sometimes assumed. Once the new particle was shown to have properties consistent with SM expectations – albeit with significant experimental uncertainties –, there was a broad agreement that ‘a’ Higgs boson had been found. Physicists adopted a two-pronged strategy. On the one hand, they treated the particle as a SM Higgs boson and tried to establish its properties with higher precision; on the other hand, they searched for any hints of physics beyond the SM. This motivates our first philosophical thesis: the Higgs discovery, being of fundamental importance and establishing a new kind of particle, represented a crucial experiment if one interprets this notion in an appropriate sense. By embedding the LHC into the tradition of previous precision experiments and the experimental strategies thus established, underdetermination and confirmational holism are kept at bay. Second, our case study suggests that criteria of theory (or model) preference should be understood as epistemic and pragmatic values that have to be weighed in factual research practice. The Higgs discovery led to a shift from pragmatic to epistemic values as regards the mechanisms of electroweak symmetry breaking. Complex criteria, such as naturalness, combine epistemic and pragmatic different values, but are coherently applied by the community

Model Choice and Crucial Tests. On the Empirical Epistemology of the Higgs Discovery

Abstract: Our paper discusses the epistemic attitudes of particle physicists on the discovery of the Higgs boson at the Large Hadron Collider (LHC). It is based on questionnaires and interviews made shortly before and shortly after the discovery in 2012. We show, to begin with, that the discovery of a Standard Model (SM) Higgs boson was less expected than is sometimes assumed. Once the new particle was shown to have properties consistent with SM expectations – albeit with significant experimental uncertainties –, there was a broad agreement that ‘a’ Higgs boson had been found. Physicists adopted a two-pronged strategy. On the one hand, they treated the particle as a SM Higgs boson and tried to establish its properties with higher precision; on the other hand, they searched for any hints of physics beyond the SM. This motivates our first philosophical thesis: the Higgs discovery, being of fundamental importance and establishing a new kind of particle, represented a crucial experiment if one interprets this notion in an appropriate sense. By embedding the LHC into the tradition of previous precision experiments and the experimental strategies thus established, underdetermination and confirmational holism are kept at bay. Second, our case study suggests that criteria of theory (or model) preference should be understood as epistemic and pragmatic values that have to be weighed in factual research practice. The Higgs discovery led to a shift from pragmatic to epistemic values as regards the mechanisms of electroweak symmetry breaking. Complex criteria, such as naturalness, combine epistemic and pragmatic different values, but are coherently applied by the community

First experiences with the ATLAS Pixel Detector Control System at the Combined Test Beam 2004

Detector control systems (DCS) include the read out, control and supervision of hardware devices as well as the monitoring of external systems like cooling system and the processing of control data. The implementation of such a system in the final experiment has also to provide the communication with the trigger and data acquisition system (TDAQ). In addition, conditions data which describe the status of the pixel detector modules and their environment must be logged and stored in a common LHC wide database system. At the combined test beam all ATLAS subdetectors were operated together for the first time over a longer period. To ensure the functionality of the pixel detector a control system was set up. We describe the architecture chosen for the pixel detector control system, the interfaces to hardware devices, the interfaces to the users and the performance of our system. The embedding of the DCS in the common infrastructure of the combined test beam and also its communication with surrounding systems will be discussed in some detail.Comment: 6 pages, 9 figures, Pixel 2005 proceedings preprin

Test Beam Results of Geometry Optimized Hybrid Pixel Detectors

The Multi-Chip-Module-Deposited (MCM-D) technique has been used to build hybrid pixel detector assemblies. This paper summarises the results of an analysis of data obtained in a test beam campaign at CERN. Here, single chip hybrids made of ATLAS pixel prototype read-out electronics and special sensor tiles were used. They were prepared by the Fraunhofer Institut fuer Zuverlaessigkeit und Mikrointegration, IZM, Berlin, Germany. The sensors feature an optimized sensor geometry called equal sized bricked. This design enhances the spatial resolution for double hits in the long direction of the sensor cells.Comment: Contribution to Proceedings of Pixel2005 Workshop, Bonn Germany 200

Model Choice and Crucial Tests. On the Empirical Epistemology of the Higgs Discovery

Abstract: Our paper discusses the epistemic attitudes of particle physicists on the discovery of the Higgs boson at the Large Hadron Collider (LHC). It is based on questionnaires and interviews made shortly before and shortly after the discovery in 2012. We show, to begin with, that the discovery of a Standard Model (SM) Higgs boson was less expected than is sometimes assumed. Once the new particle was shown to have properties consistent with SM expectations – albeit with significant experimental uncertainties –, there was a broad agreement that ‘a’ Higgs boson had been found. Physicists adopted a two-pronged strategy. On the one hand, they treated the particle as a SM Higgs boson and tried to establish its properties with higher precision; on the other hand, they searched for any hints of physics beyond the SM. This motivates our first philosophical thesis: the Higgs discovery, being of fundamental importance and establishing a new kind of particle, represented a crucial experiment if one interprets this notion in an appropriate sense. By embedding the LHC into the tradition of previous precision experiments and the experimental strategies thus established, underdetermination and confirmational holism are kept at bay. Second, our case study suggests that criteria of theory (or model) preference should be understood as epistemic and pragmatic values that have to be weighed in factual research practice. The Higgs discovery led to a shift from pragmatic to epistemic values as regards the mechanisms of electroweak symmetry breaking. Complex criteria, such as naturalness, combine epistemic and pragmatic different values, but are coherently applied by the community