NLO jet production in k_T factorization

We discuss the inclusive production of jets in the central region of rapidity in the context of k_T-factorization at next-to-leading order (NLO). Calculations are performed in the Regge limit making use of the NLO BFKL results. We introduce a jet cone definition and carry out a proper phase--space separation into multi-Regge and quasi-multi-Regge kinematic regions. We discuss two situations: scattering of highly virtual photons, which requires a symmetric energy scale to separate impact factors from the gluon Green's function, and hadron-hadron collisions, where a non-symmetric scale choice is needed.Comment: 7 pages, 1 figure, prepared for the 12th International Conference on Elastic and Diffractive Scattering, DESY, Hamburg, 21-25 May 200

Perceptions of the effectiveness of a global diversity network.

“The motivation is that it is at the heart of our work. It’s what matters more than anything, you know, I think EO&D principles, if we get those values, you know, our core values right, as an organisation, if we walk the talk in a sense in all of this, then everything else falls out of it as a consequence. We will build relationships, we will build the right projects, we’ll deliver impact, we’ll scale up, we’ll bring in the income, you know if I get that right. So what motivates me is the feeling that this is the most important thing. The irony is it doesn’t feel like that often, it feels like it’s a kind of added on organisationally. I’m not convinced the organisation sees EO&D that way, but that’s what motivates me. Actually believing, believing in the core values.” GDN Representative N1. The research takes place in the British Council which is the UK’s principal cultural relations organisation and a non departmental public body with offices in 110 countries. The British Council has its headquarters in London, where the researcher is based and in 2009 it marked its 75th anniversary. It therefore has a long history and wide international network. Consistent with the British Council's cultural relations role which concerns itself with building trust and understanding between the UK and other countries, matters of equality and diversity are an important aspect of not only its public face and activities, but its internal workings too. Its geographical spread and consequent diversity raise challenges however. A key challenge with wider resonances, confirmed by the Literature Review, is how to achieve the coherence and cohesion necessary for a shared, organisational identity and an appropriate and viable joined up approach to equality and diversity, whilst also respecting, valuing and managing diversity and cultural difference. In response, the British Council has, amongst other things, established a Global Diversity Network (GDN) of regional representatives who are deemed to be an important resource in this process. However the Diversity Unit which leads and manages the British Council’s equality and diversity agenda and the Global Diversity Network, believe that the Network is not as effective as it could be and the reasons why this is the case need to be explored. As a result the research has focused on the members. In doing so it has interrogated how they perceive they fulfil their role, the difficulties they face, their learning and development needs and explored in greater depth the perceptions of a contrasting group of strong and weak performers. The perceptions and evaluation of wider stakeholders are also incorporated. The ultimate aim, through a case study and action research approach, is to improve the GDN’s effectiveness. What emerges challenges the alleged research problem and highlights a number of things not previously known or considered. This includes the finding that the Network is perceived by its members and its stakeholders as effective but under resourced and there are gaps in how it has been managed and supported by the Diversity Unit. In addition, the research surfaced the existence of 'ideal' GDN members and no concerns of significance about the relevance of equality and diversity within the British Council's varying operating environments. A number of recommendations which are intended to support the GDN to be more effective ,and thereby alleviate pressure on the Diversity Unit, as well as contribute to improved, sustainable organisational performance, are proposed. A key recommendation relates to additional resources and addressing the learning and development needs of GDN members by making use of and building on the British Council’s Diversity Assessment Framework; this being the potent tool that supports and measures efforts to mainstream equality and diversity organisation wide. Recommendations are at various stages of implementation with some that await Executive Board endorsement. Dissemination of the research findings will take place internally and externally and internationally. This is in order to add to the limited body of knowledge about the approaches global organisations adopt in managing equality and diversity, revealed both by the Literature Review and the experiences of the Diversity Unit

Inclusive Diffraction at HERA

New precision measurements of inclusive diffractive deep-inelastic ep scattering interactions, performed by the H1 and ZEUS collaborations at the HERA collider, are discussed. A new set of diffractive parton distributions, determined from recent high precision H1 data, is presented.Comment: 5 pages, to appear in the proceedings of the 31st Intl. Conference on High Energy Physics ICHEP 2002, Amsterdam, July 200

Probabilistic Linear Solvers: A Unifying View

Several recent works have developed a new, probabilistic interpretation for numerical algorithms solving linear systems in which the solution is inferred in a Bayesian framework, either directly or by inferring the unknown action of the matrix inverse. These approaches have typically focused on replicating the behavior of the conjugate gradient method as a prototypical iterative method. In this work surprisingly general conditions for equivalence of these disparate methods are presented. We also describe connections between probabilistic linear solvers and projection methods for linear systems, providing a probabilistic interpretation of a far more general class of iterative methods. In particular, this provides such an interpretation of the generalised minimum residual method. A probabilistic view of preconditioning is also introduced. These developments unify the literature on probabilistic linear solvers, and provide foundational connections to the literature on iterative solvers for linear systems

Smooth optimal control with Floquet theory

This paper describes an approach to construct temporally shaped control pulses that drive a quantum system towards desired properties. A parametrization in terms of periodic functions with pre-defined frequencies permits to realize a smooth, typically simple shape of the pulses; their optimization can be performed based on a variational analysis with Floquet theory. As we show with selected specific examples, this approach permits to control the dynamics of interacting spins, such that gate operations and entanglement dynamics can be implemented with very high accuracy

Generalised coinduction

Final coalgebras of a functor F are suited for an abstract description of infinite datatypes and dynamical systems. Functions into such a domain are specified by coinductive definitions. The format these specifications take when their justification is directly based on finality is called the coiteration schema here. In applications it often turns out to be too rigid to allow for a convenient description of the functions under consideration. Thus, generalisations or variations are desired. We introduce a generic ?-coiteration schema that can be instantiated by a distributive law ? of some functor T over F and show that - under mild assumptions on the underlying category - one obtains principles which uniquely characterise arrows into the carrier of a final F-coalgebra as well. Certain instances of ?-coiteration can be shown to specify arrows that fail to be coiterative. Examples are the duals of primitive recursion and course-of-value iteration, which are known extensions of coiteration. One can furthermore obtain schemata justifying recursive specifications that involve operators such as arithmetic operations on power series, regular operators for languages, or parallel and sequential composition of processes. Next, the same type of distributive law ? is used to generalise coinductive proof techniques. To this end, we introduce the notion of a ?-bisimulation relation, many instances of which are weaker than the conventional definition of a bisimulation. It specialises e.g. to what could be called bisimulation up-to-equality or bisimulation up-to-context for contexts built from operators of the type mentioned above. We give a proof showing that every ?-bisimulation only contains pairs of bisimilar states. This principle leads to simpler proofs through the use of less complex relations

Inhomogeneous gas model for electron mobility in high density neon gas

Experimental studies of electron mobilities in Neon as a function of the gas density have persistently shown mobilities up to an order of magnitude smaller than expected and predicted. A previously ignored mechanism (gas in--homogeneity which is negligible in the thermal mobilities for He and other gases) is found to reproduce the observed Neon mobilities accurately and simply at five temperatures with just one variable parameter. Recognizing that a gas is not a homogeneous medium, a variation in local density combined with the quantum multi--scattering theory, shifts the energy and cross section -- which in turn changes the collision probability and finally the mobilities. A lower density where a momentum transfer interaction occurs moves the mobility strongly in the same direction as the anomalous experiments. By going backwards from the observed mobilities, the collision frequency at each temperature and density is made to reproduce the experimental data by looking for the local (as opposed to average) density at which the (rare) momentum transfer interactions occur. These density deviations give a picture of the size and behavior of the wave packets for electron motion which looks very much like the often discussed wave function collapse.Comment: 18 pages, 5 figure