We determine the full structure of the leading (double-pole) divergences of O(p6) in the meson sector of chiral perturbation theory. The field theoretic basis for this calculation is described. We then use an extension of this result to determine the p6 contributions containing double chiral logarithms (L2), single logarithms times p4 constants (L × Lr i) and products of two p4 constants (Lr i × L

We calculate the leading quark mass corrections of order mqlog(mq), mq and m3/2 q to the vector meson decay constants within heavy vector meson chiral perturbation theory. We discuss the issue of electromagnetic gauge invariance and the heavy mass expansion. Reasonably good fits to the observed decay constants are obtained.

We properly define off-shell K → π transition amplitudes and use them to extract information for on-shell K → ππ amplitudes within Chiral Perturbation Theory. At order p2 in the chiral expansion all three parameters of weak interaction can be determined. At order p4 we are able to fix eleven additional constants out of thirteen contributing to off-shell K → π transitions, which leaves four undeter

Within Chiral Perturbation Theory (CHPT) we compute the form factors A, V and γ = A/V in the π → lνγ decay to O(p6). A and γ obtain corrections of order 25%.

We present technical details of the evaluation of the elastic ππ scattering amplitude to two loops in chiral perturbation theory. In particular, we elaborate on the renormalization procedure at the two-loop order and on the evaluation of the relevant Feynman diagrams that can all be expressed in terms of elementary functions. For the sake of clarity, we discuss these matters both in the N-componen

We discuss the vector meson masses within the context of chiral perturbation theory performing an expansion in terms of the momenta, quark masses and 1/Nc. We extend the previous analysis to include isospin breaking effects and also include up to order p4. We discuss vector meson chiral perturbation theory in some detail and present a derivation from a relativistic Lagrangian. The unknown coeffici

Chiral perturbation theory relates the |S|=2 matrix element K0|(sd)V-A×(sd)V-A|K0 to the |S|=1 matrix element +0|(sd)V-A(uu)V-A+(su)V- A×(ud)V-A-(sd)V-A(dd)V-A|K+. The latter matrix element is measured in K++0 decay and the former matrix element is relevant for the predictions that the standard model makes for CP nonconservation in K0-K0 mixing. In this paper the corrections of order mK4 lnmK2 to

We discuss hyperon decays and hyperon magnetic moments using a chiral lagrangian where the baryons appear as solitons. Some relations are derived using the semiclassical approximation.

The contribution of electromagnetic "Penguin"-type diagrams to ε{lunate}′/ε{lunate} is examined in the standard six-quark model.

The predictions of chiral perturbation theory for the weak non-leptonic decays of hyperons are examined beyond the leading order. For the S-wave amplitudes we find that the leading corrections to lowest order chiral perturbation theory preserve the vanishing of the Σ+ → nπ+ amplitude. However, the Lee-Sugawara relation gets a large correction indicating a breakdown of chiral perturbation theory fo

A new scenario accounting for the production of monojets with large missing transverse energy is described and a specific model implementing it is constructed. The production rate for monojets is calculated.

Models are considered which have no small Yukawa couplings unrelated to symmetry. This situation is generic in higher dimensional unification where Yukawa couplings are predicted to have a strength similar to the gauge couplings. Generations have then to be differentiated by symmetry properties and the structure of fermion mass matrices is given in terms of quantum numbers alone. Possible symmetri

We investigate unified models where all small quantities in the fermion mass matrices are given in terms of one small ratio of symmetry breaking scales. We describe for a U(1) generation symmetry how the size of masses and mixings is determined, including possible contributions from heavy mirror quarks and leptons. This can be used for computerized model scanning. We search for realistic mass patt

We present a model with continuous or discrete abelian generation group G, which predicts all orders of magnitude for fermion masses ad mixings correctly as a function of only one small parameter φS M ≈ 1 10. Here φS is the scale of G symmetry breaking and M the fundamental mass scale of the theory. No small Yukawa couplings or special choices of the scalar potential are needed. We perform a syste

En sammantällning av de 40 orientaliska mynt som framkommit på anlöpsplatsen Vester Egesborg, Själland. Mynten analyseras med hänsyn till kronologi, ursprung och grad av fragmentering. Jämförelser görs med andra vikingatida handels- och centraplatser med orientaliska mynt som Kaupang, Uppåkra, Tissø, Birka och Strøby-Toftegård.

We examine patterns where ratios of the fermion masses and the W-boson mass (xi= mi mw) are proportional to powers of a small parameter λ(xi=ciλPi). For a simple estimate of the uncertainty in the coefficients ci we determine the allowed values of Pi and the corresponding range of λ. Using this information we search for realistic patterns in a large class of anomaly-free SU(3)×SU(2)×U(1)×U(1) mode

We calculate within chiral perturbation theory the cross section for γγ→π0π0 and γγ→π+π- to next-to-leading order. The first process only depends on the one-loop contributions and forms a test of chiral perturbation theory. We also calculate the pion electromagnetic form factor and compare it to recent data.

We present a discussion of the treatment of 1 Nc-corrections in chiral perturbation theory for nonleptonic weak processes. We compare the approach with an explicit cutoff and dimensional regularization in chiral perturbation theory and present evidence that they are equivalent. The quadratic dependence on the cutoff can be subtracted consistently at each level of 1 Nc. We discuss the identificatio

We study the value of the light quark masses combination mu + md in QCD using both Finite Energy Sum Rules and Laplace Sum Rules. We have performed a detailed analysis of both the perturbative QCD and the hadronic parametrization inputs needed in these Sum Rules. As main result, we obtain mu (1 GeV2 + md (1 GeV2) = (12 ± 2.5) MeV for the running MS masses.