Electroweak Baryogenesis with dimension-6 Higgs interactions

We present the computation of the baryon asymmetry in the SM amplified by dimension-6 Higgs interactions using the WKB approximation. Analyzing the one-loop potential it turns out that the phase transition is strongly first order in a wide range of the parameters. It is ensured not to wash out the net baryon number gained previously even for Higgs masses up to at least 170 GeV. In addition dimension-6 operators induce new sources of CP violation. Novel source terms which enhance the generated baryon asymmetry emerge in the transport equations. This model predicts a baryon to entropy ratio close to the observed value for a large part of the parameter space.Comment: 10 pages, 4 figures, Talk given at the 8th International Moscow School of Physic

Chern-Simons Number Diffusion and Hard Thermal Loops on the Lattice

We develop a discrete lattice implementation of the hard thermal loop effective action by the method of added auxiliary fields. We use the resulting model to measure the sphaleron rate (topological susceptibility) of Yang-Mills theory at weak coupling. Our results give parametric behavior in accord with the arguments of Arnold, Son, and Yaffe, and are in quantitative agreement with the results of Moore, Hu, and Muller.Comment: 43 pages, 6 figure

Comment on `Pressure of Hot QCD at large N_f'

It is argued why quasiparticle models can be useful to describe the thermodynamics of hot QCD excluding, however, the case of a large number of flavors, for which exact results have been calculated by Moore.Comment: 5 pages, 2 figures (version accepted for publication

Comment on and Erratum to "Pressure of Hot QCD at Large N_f"

We repeat and correct the recent calculation of the thermodynamic potential of hot QCD in the limit of large number N_f of fermions. The new result for the thermal pressure turns out to agree significantly better with results obtained from perturbation theory at small coupling. For large coupling, a nonmonotonic behaviour is reproduced, but the pressure of the strongly coupled theory does not exceed the free pressure as long as the Landau pole ambiguity remains negligible numerically.Comment: 9 pages, 3 figures, JHEP3; v2: version accepted for publication in JHEP (title changed, 1 footnote added, 1 reference updated, content otherwise unchanged

The Baryon asymmetry in the Standard Model with a low cut-off

We study the generation of the baryon asymmetry in a variant of the standard model, where the Higgs field is stabilized by a dimension-six interaction. Analyzing the one-loop potential, we find a strong first order electroweak phase transition for Higgs masses up to at least 170 GeV. Dimension-six operators induce also new sources of CP violation. We compute the baryon asymmetry in the WKB approximation. Novel source terms in the transport equations enhance the generated baryon asymmetry. For a wide range of parameters the model predicts a baryon asymmetry close to the observed value.Comment: 22 pages, latex, 6 figure

The Bright and the Dark Side of Malin 1

Malin 1 has long been considered a prototype giant, dark matter dominated Low Surface Brightness galaxy. Two recent studies, one based on a re-analysis of VLA HI observations and the other on an archival Hubble I-band image, throw a new light on this enigmatic galaxy and on its dark/luminous matter properties.Comment: 4 pages, 3 figures, to appear in the Proceedings of the 41st ESLAB Symposium "The Impact of HST on European Astronomy", 29 May to 1 June 2007, ESTEC, Noordwijk, N

Hard Thermal Loops and the Sphaleron Rate on the Lattice

We measure the sphaleron rate (topological susceptibility) of hot SU(2) gauge theory, using a lattice implementation of the hard thermal loop (HTL) effective action. The HTL degrees of freedom are implemented by an expansion in spherical harmonics and truncation. Our results for the sphaleron rate agree with the parametric prediction of Arnold, Son and Yaffe: Gamma ~ \alpha^5 T^4.Comment: 3 page

Chern-Simons number asymmetry from CP violation at electroweak tachyonic preheating

We consider the creation of non-zero Chern-Simons number in a model of the early Universe, where the Higgs field experiences a fast quench at the end of inflation and subsequently rolls down its potential barrier. Neglecting the expansion, we perform numerical lattice simulations in the Abelian Higgs model in 1+1 dimensions with an added phenomenological C and P violating term during this stage of so-called tachyonic preheating. The results suggest that even the sign of the Chern-Simons and thus baryon number is dependent on the ratio of the Higgs to W mass. We also discuss the appropriate choice of vacuum initial conditions for classical simulations.Comment: 24 pages, 17 figures, added references, published versio

Popliteal aneurysms: a 10-year experience

Background:Popliteal aneurysms account for 70% of peripheral arterial aneurysms and, if untreated, pose a serious threat to the affected limb. Debate continues about the best form of treatment especially for asymptomatic lesions.Methods:We reviewed the computer records and charts of patients seen at this department with a diagnosis of popliteal aneurysm over the last 10 years. Patients who had not been seen within the last year were followed-up through their G.P.Results:Twenty-four patients (M 23/F 1) presented with 40 popliteal aneurysms. The mean age was 63.5±9 years. Symptoms were present in 23 of the affected limbs while 17 were asymptomatic. Thirty were treated surgically and 10 followed with regular ultrasound. The mean diameter of the repaired aneurysms was 3.3±1 cm. Aneurysms <2 cm were more likely to be asymptomatic. No limbs were lost in patients undergoing elective repair of popliteal aneurysms. The secondary patency and limb salvage rates at 3 years were 84% and 96% respectively. Conservative management of asymptomatic lesions <2 cm was not complicated by the development of symptoms.Conclusions:Elective repair of popliteal aneurysms by exclusion and bypass is a safe, effective and durable technique. Small asymptomatic lesions can be safely managed with close follow-up