Sökresultat

We present the results of a search for relations between observables that are independent of the Chiral Perturbation Theory (ChPT) Next-to-Next-to-Leading Order (NNLO) Low-Energy Constants (LECs). We have found some relations between observables in $\pi\pi$, $\pi K$ scattering and $K_{l4}$ decay which have been evaluated numerically using the old fit (fit 10 in~\cite{Amoros:2001cp}) of the NLO LEC

We present work going on calculating the kaon BK parameter in the 1/Nc expansion. The goal of this work is to analyze analytically in the presence of chiral corrections this phenomenologically very important parameter. We present the method used and preliminary results for the chiral limit value for which we get the invariant BKchi=0.29 +- 0.15. We also give some analytical indications of why the

Different hadronization effects in high energy interactions are investigated. The frame-work is the Lund model for the strong interaction. A model for baryon production in jet fragmentation is presented and extended to baryon remnant fragmentation in deep inelastic scattering and hadron--hadron collisions. Observables designed to probe hadronization effects on p_t correlations are show

I present the status of the ThePEG project for creating a common platform for implementing C++ event generators. I also describe briefly the status of the new versions of HERWIG++ and Ariadne which are implemented using this framework.

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 defi

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We review the status of the hadronic light-by-light contribution to the muon anomalous magnetic moment and critically compare recent calculations. We also study in detail which momentum regions the pi0 exchange main contribution originates. We also argue that amu{light-by-light} = (11 pm 4) times 10^-10 encompasses the present understanding of this contribution and comment on some direct

These are the proceedings of the workshop on ``Effective Field Theories in Nuclear, Particle and Atomic Physics'' held at the Physikzentrum Bad Honnef of the Deutsche Physikalische Gesellschaft, Bad Honnef, Germany from December 13 to 17, 2005. The workshop concentrated on Effective Field Theory in many contexts. A first part was concerned with Chiral Perturbation Theory in its various settings an

These are the proceedings of the workshop on ``Effective Field Theories of QCD'' held at the Physikzentrum Bad Honnef of the Deutsche Physikalische Gesellschaft, Bad Honnef, Germany from November 26 to 30, 2001. The workshop concentrated on Chiral Perturbation Theory in its various settings, its relations with lattice QCD and dispersion theory and the use of effective field theories in systems wit

The LDC formalism for DIS can describe HERA structure functions, and also agrees well with CTEQ and MRST gluon distributions. It is also suitable for hadronic collisions, and provides a strong connection between ep and pp reactions. Some preliminary results are presented.

We have computed the quark anti-quark expectation value in finite volume at two loop in chiral perturbation theory and compare it with a formula obtained in analogy to the Luscher formula for pion mass in finite volume. We observe that due to the small finite size correction at two loop it is not possible to obtain conclusions on the accuracy of the extended Luscher formula

This thesis concentrates on one of the indirect Dark Matter (DM) detection methods, namely through observations of Very High Energy (VHE) $\gamma$-ray signals from DM annihilation (or decay) in cosmic sources using the Imaging Atmospheric Cherenkov Technique (IACT). We discuss the particle physics and astrophysical aspects of those observations and perform several calculations which lead to an est

Context. Extreme precision radial-velocity spectrometers enable extreme precision in stellar spectroscopy. Searches for low-mass exoplanets around solar-type stars are limited by various types of physical variability in stellar spectra, such as the short-term jittering of apparent radial velocities on levels of ∼2 m s-1. Aims. To understand the physical origins of radial-velocity jittering, the so

In a single theoretical framework, real and virtual photon interactions are modeled for gamma-p and gamma-gamma collisions. The description covers aspects from the production of jets to total cross sections, where special emphasis is put on the range of uncertainty in the modeling of a resolved photon component. Our approach extends on a model for photoproduction, where the total cross section is

Most of the traditional technicolor-based models are known to be in a strong tension with the electroweak precision tests. We show that this serious issue is naturally cured in strongly coupled sectors with chiral-symmetric vectorlike gauge interactions in the framework of the gauged linear sigma model. We discuss possible phenomenological implications of such a nonstandard chiral-symmetric techni