Sökresultat

Virtual Compton scattering (VCS) on the proton has been studied at the Jefferson Laboratory using the exclusive photon electroproduction reaction ep→epγ. This paper gives a detailed account of the analysis which has led to the determination of the structure functions PLL-P TT/ε and PLT and the electric and magnetic generalized polarizabilities (GPs) αE(Q2) and βM(Q2) at values of the four-momentum

After a brief discussion of the statistics available to the four LEP experiments at the time of writing and an overview of B-event characteristics, the authors consider in particular the theory, practice and potential pitfalls of neural networks, a new approach to B tagging which attracted a great deal of interest. They then consider some of the QCD aspects of heavy flavour physics. Finally there

We present a toolkit, written in the C++ programming language, for event generation in high energy physics. The toolkit, called MC++, is an attempt to formulate the event generation chain in high in high energy p[article collisions in a transparent and generic way using object oriented programming techniques.

We present a model based upon string dynamics for the small x and large k⊥ parts of the structure functions of a hadron. These ocean partons are taken as those available in the virtual string states, which are resolved by the field pulse q, in case the process is considered as a measuring process. The resulting distributions will for sufficiently small x (x⩽O(Q−4)) behave as 1/x in case we use the

The use of Object Oriented Programming languages and techniques for the development of Monte Carlo simulators for particle production and decay is discussed. For illustration, two specific "template" programs are presented written in Objective-C and in C++, respectively

Using a neural-network classifier we are able to separate gluon from quark jets originating from Monte Carlo–generated e+e− events with 85%–90% accuracy.

We present results from Monte Carlo calculations of the string effect and the double inclusive correlation of particle flows for three-fold symmetric three-jet events in e+e− annihilation reactions at different energies. We find that the perturbative phase of the jet evolution quickly becomes dominant as energy increases.

We show that the hard qq̄ production is very sensitive to the details of the parton shower and that our treatment based on the dipole approximation gives significantly larger production than “conventional” parton showers. For our model we find qualitative agreement with experimental data for the Kπ ratio and D-meson production in high-pT jets.

We have searched for direct photons of low PT (≤1.0 GeV/c) at θc.m.=90° in pp collisions at √s =63 GeV. We used two independent methods: direct detection in NaI crystals and conversion to e+e− pairs. No signal is observed; the photon spectrum is well described by the decay of hadrons. The result is consistent with a direct low-PT photon signal reported at √s =12 GeV, but excludes a rapid growth of

We present a method to implement the gluon splitting process, g → QQ, into the dipole approximation to QCD cascades. It is known that due to the uncertainties in the interpolation between the pole regions, there are large uncertainties in the results. We show that there are further uncertainties due to the ordering in phase space of the gluon emission and gluon splitting processes. We present two

The migration of the great snipe Gallinago media was previously poorly known. Three tracks in 2010 suggested a remarkable migratory behaviour including long and fast overland non-stop flights. Here we present the migration pattern of Swedish male great snipes, based on 19 individuals tracked by light-level geolocators in four different years. About half of the birds made stopover(s) in northern Eu

We present a framework for deep inelastic scattering, with bound state properties in accordance with a QCD force field acting like a vortex line in a colour superconducting vacuum, which implies some simple coherence effects. Within this scheme one may describe the results of present energies very well, but one obtains an appreciable depletion of gluon radiation in the HERA energy regime.

Biomass is becoming particularly important as a starting material for advanced carbon structures. In this study, we found interesting nanostructures on the surface of burnt spaghetti using scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX) for analysis. The structures were elongated and finger-like, with evidence that the tubes have

In the master narrative of rape some women’s testimonies of sexual violence become particularly tainted with doubt and disbelief. Conversely, only some men’s sexually violent acts are unconditionally marked by guilt and blame. The chapter stresses the spatial dimension of this master narrative of rape. With an analysis of two hyper-medialised Swedish gang rape cases, it is highlighted how a moral

Objective: Epidemiologic data indicate decreased risk for development, growth, and rupture of abdominal aortic aneurysm (AAA) among patients with type 2 diabetes mellitus (DM). We therefore evaluated mortality and cardiovascular morbidity after acute repair of AAA in diabetic and nondiabetic patients. Methods: In this nationwide observational cohort study of patients registered in the Swedish Vasc