Fluctuations, Saturation, and Diffractive Excitation at low x

Diffractive excitation is usually described by the Good--Walker formalism for low masses, and by the triple-Regge formalism for high masses. In the Good-Walker formalism the cross section is determined by the fluctuations in the interaction. By taking the fluctuations in the BFKL ladder into account, it is possible to describe both low and high mass excitation in the Good-Walker formalism. In high energy pp collisions the fluctuations are strongly suppressed by saturation, which implies that pomeron exchange does not factorise between DIS and pp collisions. The Dipole Cascade Model reproduces the expected triple-Regge form for the bare pomeron, and the triple-pomeron coupling is estimated.Comment: 4 pages, proceedings from Diffraction 201

Quasielastic Scattering in the Dipole Model

A series of previous papers develops a dipole model in initial state impact parameter space that includes subleading effects such as running alpha strong, unitarity, confinement and saturation. Here some recent work is presented, where the model is applied to a new set of data: vector meson production in photon-proton, DVCS and t-dependence in elastic proton-proton collisions. This allows us to tune a more realistic model of the proton wavefunction from the pp data, and confirm the predictive power of the model in high Q2 of DVCS and vector meson production. For low Q2 vector meson resonances dominate the photon wavefunction, making our predictions depend on a tuned parametrisation in this range.Comment: Published in Proceedings of the 38th International Symposium on Multiparticle Dynamics (ISMD08

Exclusive final states in diffractive excitation

In this paper we describe a formalism for generating exclusive final states in diffractive excitation, based on the optical analogy where diffraction is fully determined by the absorption into inelastic channels. The formalism is based on the Good--Walker formalism for diffractive excitation, and it is assumed that the virtual parton cascades represent the diffractive eigenstates defined by a definite absorption amplitude. We emphasize that, although diffractive excitation is basically a quantum-mechanical phenomenon with strong interference effects, it is possible to calculate the different interfering components to the amplitude in an event generator, add them and thus calculate the reaction cross section for exclusive diffractive final states. The formalism is implemented in the DIPSY event generator, introducing no tunable parameters beyond what has been determined previously in studies of non-diffractive events. Some early results from DIS and proton-proton collisions are presented, and compared to experimental data

Eccentricity and elliptic flow in proton-proton collisions from parton evolution

It has been argued that high-multiplicity proton-proton collisions at the LHC may exhibit collective phenomena usually studied in the context of heavy-ion collisions, such as elliptic flow. We study this issue using DIPSY - a Monte Carlo event generator based on the QCD dipole model. We calculate the eccentricity of the transverse area defined by the spatial distribution of produced gluons. The resulting elliptic flow is estimated to be about 6%, comparable to the value in nucleus-nucleus collisions at RHIC and the LHC. Experimentally, elliptic flow is inferred from the azimuthal correlation between hadrons, which receives contributions from collective flow, and from various other effects referred to as "nonflow". We discuss how to identify in experiments the signal of flow in the presence of large nonflow effects.Comment: v2: Four-particle correlation added, improved discussions on the signatures of flow. v3: Improved treatment of fluctuations in the flow analysis. v4: Minor changes for journal submissio

An enhanced communication model

The concept of information is often taken for more or less granted in research about information systems. This paper introduces a model starting with Shannon and Weaver data transmission model and ends with knowledge transfer between individual persons. The model is in fact an enhanced communication model giving a framework for discussing problems in the communication process. A specific feature of the model is the aim for providing design guidelines in designing the communication process. The article ends with identifying a need for develop the model further to incorporate also communication within and between organisations of different kinds.El término "información" no se valora a menudo en la investigación de sistemas de información. Este artículo introduce un modelo que comienza con el modelo de transmisión de información de Shannon, un matemático e ingeniero electrónico, y Weaver, un científico, y termina con la transferencia de conocimientos entre individuos. De hecho, el modelo es uno de comunicación mejorado, que proporciona un marco para debatir problemas en el proceso de comunicación. Un modelo de comunicación es el objetivo para aportar pautas de diseño en el diseño del proceso de comunicación. El artículo concluye con la identificación de una necesidad de desarrollar más allá el modelo, para incorporar también la comunicación dentro y entre los diferentes tipos de organizaciones

Becoming Professor. With Almost no Publications

I consider my career as rather exceptional. I think I am the only living person in Sweden who achieved a professor chair with only one international journal publication; a publication I use as an example of a totally incomprehensible text! The following is the story of how I achieved this. I first describe two important issues that have governed my decisions in the career: Being interpretivist in a dominating positivist research paradigm and my decision not to publish. This is important for understanding my interpretation of what was happening. Then I describe the four universities where I have worked, first by providing the story, then describing how the discipline developed at that place and finally some reflections on the research we conducted. I summarize by giving an historic overview of informatics as I perceive it after 44 years of teaching and finally I reflect upon my career according to my goals

Appscapes in everyday life: Studying Mobile Datafication from an Infrastructural User Perspective

It has long been acknowledged that the use of ‘free’ mobile apps comes at a price, but few empirical studies have looked into this supposed trade-off. This article combines qualitative interviews with mappings of infrastructures for datafication in order to study the implications of mobile app usage from the perspective of individual users. It analyses users’ understanding of online tracking, maps the infrastructural tenets of mobile datafication, and finds a disconnect between what users believe happens to their data and the actua data harvesting and distribution mechanisms of their apps. We thereby argue that users’ resigned attitudes should be understood in light of the material conditions of the app economy and, as such, that user and infrastructure studies should join forces in exploring and enhancing users’ agency, empowerment and emancipation