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The present status of Chiral Perturbation Theory in the meson sector is discussed concentrating on recent developments. This write-up contains short discussions on a listing of a few historical papers, the principles behind ChPT, two-flavour ChPT including some comments about the Pion polarizability, three-flavour ChPT with a discussion of the recently found relations as tests of ChPT and prelimin
The Absolut Company har öppnat besökscentret Absolut Home i Åhus och detta har potential att medföra ett stort antal värden för orten. Forskarna har studerat bådeturistaktörers och Åhusbors syn på värden för att ta reda på hur de ställer sig till det nya besökscentret i sin ort.
A short overview of baryon weak decays and our present theoretical understanding is given. The successes and shortcomings of the various approaches are compared.
Recent work by J. Prades and myself on K → ππ is described. The first part describes our method to connect in a systematic fashion the short-distance evolution with long-distance matrix-element calculations taking the scheme dependence of the short-distance evolution into account correctly. In the second part I show the results we obtain for the ΔI = 1/2 rule in the chiral limit.
We discuss the low-energy analysis of models involving quarks and four-fermion couplings. The relation with QCD and with other models of mesons and meson plus quarks at low energies is discussed. A short description of how the heat-kernel expansion can be used to get regularization independent information, is given. The anomaly within this class of models and a physical prescription to obtain the
The effective action in the abnormal intrinsic parity sector is derived to next-to-leading order in the chiral perturbation theory expansion in the chiral limit under the assumption that chiral symmetry breaking is well described by the addition of a constituent quark mass term to the QCD action. The result is combined with the loop calculation done previously for the case of pseudoscalar decays i
The electromagnetic contribution to the K+-K0 mass difference is calculated in the 1 Nc approach including the SU(3) breaking contributions due to a non-zero strange quark mass. The short-distance contribution can be unambiguously determined in terms of the known parameters of the next-to-leading order chiral Lagrangian. The long distance part is estimated using the 1 Nc approach by Bardeen et al.
Tha amplitudes for the Kℓ4 decays are calculated to next-to-leading order in Chiral Perturbation Theory. These are then compared with the available experimental results on these decays. The values of the parameters L1, 2, 3 previously determined from ππ scattering are compared with those obtained here. A short overview of the determination of the parameters of Chiral Perturbation Theory is include
The chiral perturbation theory relations of 〈ππ|O|K〉 to 〈π|O|K〉 and 〈o|O|K〉 needed for establishing the ΔI= 1 2 rule in hadronic weak decays via lattice calculations are examined beyond leading order and the domain of validity for this relation is established.
The K → ππ system is analyzed in the chiral limit within the Standard Model. We discuss how to connect the short-distance running in the |ΔS| = 1 case to the matrix-elements calculated in a low-energy approximation in a scheme-independent fashion. We calculate this correction and the resulting Wilson Coefficients. The matrix elements are calculated to next-to-leading order in the 1/Nc expansion an
We discuss the matching between long-distance and short-distance at next-to-leading in 1/Nc and show how the scheme-dependence from the two-loop renormalization group running can be treated. We then use this method to study the three O(p2) terms contributing to non-leptonic kaon decays, namely the usual octet and 27-plet derivative terms as well as the weak mass term using the Extended Nambu Jona-
The prospect of experimental verification of the large extra dimension scenario in rare decays is discussed. The case of J/ψ and γ to photon + missing energy is calculated in detail, and it is shown that the limit on the compactification scale MS lies at present in the ten GeV range. In contrast to the quarkonium systems, signals in Kaon and Pion decays will be small.
This chapter is one of two theoretical pieces in this international collection. The aim is to challenge the traditional perception of who is a vulnerable person by discussing the concept from the vulnerability theory standpoint that basically accepts vulnerability as a universal state of being. It discusses the risk that the distribution of public services ends up being based on age absent conside
The chapter focuses on the notion of critical evaluation of information, which is an important part of media and information literacy (MIL). The concepts frictions of relevance and infrastructural meaningmaking are introduced to shed light on the information infrastructure’s significance for MIL in today’s digital media ecology. Furthermore, the chapter discusses some of the limitations inherent i
Wikis are often considered to be the core platform of peer production. This chapter delineates their most central design principles, history and affordances. Wikis are described as content management systems that allow for flexible collaboration without a defined content owner or leader. Users can modify the content and structure of documents directly in their web browser. Edits are usually archiv
