NNLO contributions to epsilon_K and rare kaon decays

We discuss the theory prediction of epsilon_K and the rare K -> pi nu nu-bar decays and review the structure and current status of higher-order contributions to these flavour changing processes in the standard model in some detail. This includes the next-to-next-to-leading order QCD calculation to the charm quark contribution to K+ -> pi+ nu nu-bar and to the charm-top quark contribution to epsilon_K. Electroweak corrections to the rare kaon decays are also discussed.Comment: 9 pages, 5 figures; talk given at the 2009 Kaon International Conference (KAON 2009), June 9 - 12, 2009, Tsukuba, Japa

Indirect probes of the trilinear Higgs coupling: gg→hgg \to h and h→γγh \to \gamma \gamma

In the framework of the Standard Model effective field theory, we examine the indirect constraints on the trilinear Higgs coupling $\lambda$ that arise from Higgs production in gluon-gluon-fusion and diphoton Higgs decays. We calculate 2-loop contributions to the $gg \to h$ and $h \to \gamma \gamma$ amplitudes that are affected by modifications of the trilinear Higgs-boson vertex. This calculation involves both the computation of anomalous dimensions and finite matching corrections. Based on our new results, we analyse the sensitivity of present and future measurements of the $hgg$ and $h \gamma \gamma$ couplings to shifts in $\lambda$. Under the assumption that $O_6 = - \lambda \left (H^\dagger H \right )^3$ is the only dimension-6 operator that alters the trilinear Higgs interactions, we find that at present the considered loop-level probes provide stronger constraints than $pp \to 2h$. At future high-energy colliders indirect ${\cal O} (5)$ determinations of the trilinear Higgs coupling may be possible, making precision measurements of $gg \to h$ and $h \to \gamma \gamma$ a useful addition to direct extractions of $\lambda$ through double-Higgs production.Comment: 17 pages, 5 figure

Searching for t->c(u)h with dipole moments

A discovery of flavour-changing Higgs-boson decays would constitute an undeniable signal of new physics. We derive model-independent constraints on the tch and tuh couplings that arise from the bounds on hadronic electric dipole moments. Comparisons of the present and future sensitivities with both the direct LHC constraints and the indirect limits from D-meson physics are also presented.Comment: 18 pages, 2 figures; v2: references added and typos corrected; coincides with version to be published in JHE

Electroweak Corrections to Bs,d→ℓ+ℓ−B_{s,d} \to \ell^+ \ell^-

We calculate the full two-loop electroweak matching corrections to the operator governing the decay B_q --> l^+ l^- in the Standard Model. Their inclusion removes an electroweak scheme and scale uncertainty of about 7% of the branching ratio. Using different renormalization schemes of the involved electroweak parameters, we estimate residual perturbative electroweak and QED uncertainties to be less than 1% at the level of the branching ratio.Comment: 16 pages, 6 figures, supplementary Mathematica file "c10.m" with analytical results; v2: references update

Zwischen Abgrenzung und Faszination. Das nationalsozialistische Deutschland in populärkulturellen dänischen Darstellungen des Zweiten Weltkriegs

The paper discusses the presentation of Nazi Germany in products of current Danish popular culture. It analyzes and compares two different, but closely connected types of media: movies and popular history magazines. It is informed by a social identity approach and demonstrates that stereotypes with respect to Nazi Germany – such as technology and masculinity – are characterized by a specific tension between otherness and fascination. It argues that memory studies have to cope with the entanglement between national framing and transnational connections. This entanglement shapes specific dynamics in memory culture

Three-Loop Mixing of Dipole Operators

We calculate the complete three-loop O(alpha_s^3) anomalous dimension matrix for the dimension-five dipole operators that arise in the Standard Model after integrating out the top quark and the heavy electroweak bosons. Our computation completes the three-loop anomalous dimension matrix of operators that govern low-energy |Delta F| = 1 flavor-changing processes, and represents an important ingredient of the next-to-next-to-leading order QCD analysis of the Bbar -> X_s gamma decay.Comment: 4 pages, 1 figure; journal version, text below Eq. (7) correcte

Universal Unitarity Triangle and Physics Beyond the Standard Model

We make the simple observation that there exists a universal unitarity triangle for all models, like the SM, the Two Higgs Doublet Models I and II and the MSSM with minimal flavour violation, that do not have any new operators beyond those present in the SM and in which all flavour changing transitions are governed by the CKM matrix with no new phases beyond the CKM phase. This universal triangle can be determined in the near future from the ratio (Delta M)_d/(Delta M)_s and sin(2 beta) measured first through the CP asymmetry in B_d^0 to psi K_S and later in K to pi nu nubar decays. Also suitable ratios of the branching ratios for B to X_{d,s} nu nubar and B_{d,s} to mu^+ mu^- and the angle gamma measured by means of CP asymmetries in B decays can be used for this determination. Comparison of this universal triangle with the non-universal triangles extracted in each model using epsilon, (Delta M)_d and various branching ratios for rare decays will allow to find out in a transparent manner which of these models, if any, is singled out by experiment. A virtue of the universal triangle is that it allows to separate the determination of the CKM parameters from the determination of new parameters present in the extensions of the SM considered here.Comment: 12 pages, 1 figur