Colour Reconnection at LEP

Two measurements are presented of estimators sensitive to the Colour Reconnection effect in WW events at LEP2. The results are compared with various phenomenological Monte Carlo implementations of the effect. A feasibility study is performed to reduce the total uncertainty in the direct W boson mass measurement at LEP2 by use of the inferred information about the Colour Reconnection effect.Comment: Proceeding of the EPS Conference on HEP, Aachen 200

Possible reduction of the total uncertainty on the W boson mass measured at LEP2

An alternative W mass estimator in e+e- -> WW -> qqqq events at LEP2 is designed to optimize the balance between the statistical uncertainty and the systematic uncertainty due to a possible Colour Reconnection effect. The preliminary result for the total uncertainty on the W mass in this channel is roughly 30 % lower then those obtained with the standard estimators, based on the SKI implementation of Colour Reconnection. Also an indirect measurement of the SKI Colour Reconnection model parameter kappa is inferred from the difference between both W mass estimators.Comment: 2 pages, 2 figures, LaTex, Contribution to Rencontres de Moriond XXXVII (Forum for Young Researchers

Analyzing equivalalences in discourse: are discourse theory and membership categorization analysis comptatible

Facing a crucial leap from political philosophy to empirical analysis, the approach to discourse analysis that arose in the aftermath of Laclau and Mouffe (1985), and that is currently known as the Essex school of discourse theory (DT), has in recent years repeatedly been accused of suffering from a methodological deficit. This paper examines to what extent membership categorization analysis (MCA), a branch of ethnomethodology that investigates lay actors' situated descriptions-in-context as practical activity, can play a part in rendering poststructuralist DT notions such as articulation and equivalence analytically tangible in empirically observable discourse. Based on a review of Laclau and Mouffe's foundational text as well as on Glynos and Howarth's recent exposition of the framework (2007), it is argued that MCA empirically substantiates many poststructuralist claims about the indeterminacy of signification. However, MCA consistently falters - and willingly so - at the point where DT would articulate emerging equivalences between identity categories as part of a second-order explanatory concept, such as Glynos and Howarth’s notion of political logic. Nevertheless, MCA also contains the kernel of an "endogenous" notion of the political that comes fairly close to DT’s all-pervasive understanding of the concept. To support these arguments, a variety of empirical sources are mobilized, ranging from the transcript of a political talk show, a newspaper report regarding a discrimination case in a dance class, to data drawn from earlier research on the way that minority members are treated by the Belgian criminal justice system

Top Quark Physics at the LHC

The Large Hadron Collider (LHC) is expected to provide proton-proton collisions at a centre-of-mass energy of 14 TeV, yielding millions of of top quark events. The top-physics potential of the two general purpose experiments, ATLAS and CMS, is discussed according to state-of-the-art simulation of both physics and detectors. An overview is given of the most important results with emphasis on the expected improvements in our understanding of physics connected to the top quark.Comment: proceedings Hadron Collider Physics Symposium 200

Classical Knowledge for Quantum Security

We propose a decision procedure for analysing security of quantum cryptographic protocols, combining a classical algebraic rewrite system for knowledge with an operational semantics for quantum distributed computing. As a test case, we use our procedure to reason about security properties of a recently developed quantum secret sharing protocol that uses graph states. We analyze three different scenarios based on the safety assumptions of the classical and quantum channels and discover the path of an attack in the presence of an adversary. The epistemic analysis that leads to this and similar types of attacks is purely based on our classical notion of knowledge.Comment: extended abstract, 13 page

Recruiting a nonlocal language for performing local identity: indexical appropriations of Lingala in the Congolese border town Goma

This article describes discursive processes by which inhabitants of the Congolese border town Goma attribute new indexical values to Lingala, a language exogenous to the area of which most Goma inhabitants only possess limited knowledge. This creative reconfiguration of indexicalities results in the emergence of three "indexicalities of the second order": the indexing of (i) being a true Congolese, (ii) toughness (based on Lingala's association with the military), and (iii) urban sophistication (based on its association with the capital Kinshasa). While the last two second-order reinterpretations are also widespread in other parts of the Congolese territory, the first one, resulting in the emergence of a Lingala as an "indexical icon" of a corresponding "language community," deeply reflects local circumstances and concerns, in particular the sociopolitical volatility of the Rwandan-Congolese borderland that renders publicly affirming one's status as an "autochthonous" Congolese pivotal for assuring a livelihood and at times even personal security. (Lingala, Democratic Republic of the Congo, Goma, orders of indexicality, language community, autochthony, Kiswahili)

Why the Disjunction in Quantum Logic is Not Classical

The quantum logical `or' is analyzed from a physical perspective. We show that it is the existence of EPR-like correlation states for the quantum mechanical entity under consideration that make it nonequivalent to the classical situation. Specifically, the presence of potentiality in these correlation states gives rise to the quantum deviation from the classical logical `or'. We show how this arises not only in the microworld, but also in macroscopic situations where EPR-like correlation states are present. We investigate how application of this analysis to concepts could alleviate some well known problems in cognitive science