B -> pi pi, New Physics in B -> pi K and Implications for Rare K and B Decays

The measured B -> pi pi, pi K branching ratios exhibit puzzling patterns. We point out that the B -> pi pi hierarchy can be nicely accommodated in the Standard Model (SM) through non-factorizable hadronic interference effects, whereas the B -> pi K system may indicate new physics (NP) in the electroweak (EW) penguin sector. Using the B -> pi pi data and the SU(3) flavour symmetry, we may fix the hadronic B -> pi K parameters, which allows us to show that any currently observed feature of the B -> pi K system can be easily explained through enhanced EW penguins with a large CP-violating NP phase. Restricting ourselves to a specific scenario, where NP enters only through Z^0 penguins, we derive links to rare K and B decays, where an enhancement of the K_L-> pi^0 nu nu_bar rate by one order of magnitude, with BR(K_L -> pi^0 nu nu_bar) > BR(K^+ -> pi^+ nu nu_bar), BR(K_L -> pi^0 e^+ e^-)=O(10^{-10}), (\sin2\beta)_{pi nu nu_bar} K* mu^+ mu^-, are the most spectacular effects. We address also other rare K and B decays, epsilon'/epsilon and B_d -> phi K_S.Comment: 6 pages, LaTeX, reference added and a few typos correced, to appear in Physical Review Letter

Investigation of the Forming Behavior of Copper Wires for the Compaction of Windings for Electric Machines

To meet the increasing demand for highly efficient electric traction drives, the compact winding process has been developed at the wbk Institute of Production Science. One key element of the process chain is the compaction of the round wire stator windings. In order to enable an estimation of the sensitivities of the influencing factors, a simplified finite element simulation model was set up in the present work. In the calculations, the number of wire layers, the layer structure and the punch stroke were selected as factors with three levels each. The evaluation was performed by means of false color images and the maximum strains and stresses in the section plane of the slots

Production-oriented design of electric traction drives with hairpin winding

In recent years, the manufacturing of stators by hairpin technology has proven its ability to fulfill the requirements on quality, productivity and robustness of traction drive applications in automotive industry. However, the uncertainty and necessity of rapid product development despite fuzzy target systems still cause that processes, machines and equipment – as well as the electric design – are often in an imperfect prototype stage at the start of production ramp-up. Due to the complex interdependencies between the stator components in combination with a high sensitivity of the overall process reliability to minor adjustments of stator design features, possible production-related weaknesses in design are often recognized first in the prototype stage of the production system. In order to reduce the economic risk resulting from these volatile technological conditions, production-oriented design based on numerical simulation methods can be applied from the beginning of product development. Therefore, several techniques for numerical process modeling are presented in this paper as possibilities to consider manufacturing constraints in an early stage of product development. For this purpose, the influence of wire dimensions on the forming process of hairpin coils is investigated using the example of rotary bending as well as the twisting process of a full stator by finite element simulations. Furthermore, a numerical approach to investigate the influence of heat input during laser welding of hairpin coils on the required stripping length is introduced

Investigation of the Thermal Characteristics of a Novel Laser Sintering Machine for Additive Manufacturing of Continuous Carbon Fibre-Reinforced Polymer Parts

This paper presents the thermal analysis of a novel laser sintering machine for additive manufacturing of continuous carbon fibre-reinforced polymer parts. The core element of this machine is a fibre integration unit with a heated fibre nozzle. With the help of an additional heat source, which is mounted on the bottom side of the fibre integration unit, the temperature of the powder bed surface is kept within the sintering window of the PA12 material used in the investigations. Different heat source variants differing in shape and material were analysed experimentally concerning the heat distribution achieved within the powder bed surface using an infrared camera. Based on the best-rated variant showing the most homogeneous heat distribution, operating points for successful continuous fibre integration were experimentally identified. An aluminium plate with a closed fibre nozzle slot and symmetrical surface heating power has proven to keep the powder bed surface reliably warm. Compared to the initial state, the resulting increased uniformity of heat-affected zones created by the heated fibre nozzle HAZ was evaluated by fabricating a horseshoe part made of PA12. Furthermore, a CCFRP flat pedal for mountain bikes demonstrated roving integration’s process reliability and reproducibility

An Approach for the Disassembly of Permanent Magnet Synchronous Rotors to Recover Rare Earth Materials

The extensive electrification of the mobility sector is a crucial part for global decarbonization. To enable a successful transition, the availability of resources must be ensured. In particular, rare earth materials used in permanent magnets of permanent magnet synchronous machines (PMSM) are already considered as a critical resource. Therefore, high performance magnets of existing PMSM rotors must be recovered and remanufactured or recycled. A major challenge to recover the magnets is their fixation inside the rotor lamination stack. Hence, this paper presents an overview of remanufacturing and recycling methods for rare earth magnets. Based on this, a disassembly process for PMSM rotors is developed, technical challenges are pointed out and automation solution are proposed. As results of an experimental study conducted on different magnet configurations, four characteristic phases for the magnet disassembly process were identified and magnets with nickel coating showed significantly higher disassembly forces than magnets with epoxy coating. Moreover, analytical and empirical approaches for modeling the consecutive phases of the disassembly process are proposed

Anatomy of Prominent B and K Decays and Signatures of CP-Violating New Physics in the Electroweak Penguin Sector

The recent observation of B_d -> pi^0 pi^0 at the B factories with a surprisingly large branching ratio represents a challenge for theory, and complements the amazingly small B_d -> pi^+ pi^- rate. We point out that all puzzling B -> pi pi features can be accommodated in the Standard Model (SM) through non-factorizable hadronic interference effects, extract the relevant parameters, and predict the CP asymmetries of B_d -> pi^0 pi^0. Using then SU(3) flavour-symmetry and plausible dynamical assumptions, we fix the hadronic B -> pi K parameters through their B -> pi pi counterparts, and determine the CKM angle gamma, with a result in remarkable accordance with the usual fits for the unitarity triangle. We may then analyse the B -> pi K system in the SM, where we find agreement with the experimental picture, with the exception of those observables that are significantly affected by electroweak (EW) penguins, thereby suggesting new physics (NP) in this sector. Indeed, a moderate enhancement of these topologies and a large CP-violating NP phase allow us to describe any currently observed feature of the B -> pi K modes, and to predict the CP-violating B_d -> pi^0 K_S observables. If we then restrict ourselves to a specific scenario where NP enters only through Z^0 penguins, we obtain a link to rare K and B decays, where the most spectacular NP effects are an enhancement of the K_L -> pi^0 nu nu_bar rate by one order of magnitude with BR(K_L -> pi^0 nu nu_bar) ~ 4 BR(K^+ -> pi^+ nu nu_bar), BR(K_L -> pi^0 e^+ e^-) = O(10^-10), (sin 2beta)_{pi nu nu_bar} < 0, and a large forward-backward CP asymmetry in B_d -> K^* mu^+ mu^-. We address also epsilon'/epsilon and other prominent decays, including B -> phi K and B -> J/psi K modes.Comment: 78 pages, 12 figures, LaTe

Miszellen zur Eisen- und Römerzeit für Prof. Dr. Sabine Rieckhoff von ihren Mitarbeitern und Schülern: Zusammenfassungen der Poster

Diese Miszellen zur Eisen- und Römerzeit sind Ihnen, liebe Frau Professor Rieckhoff zu Ihrem 60. Geburtstag gewidmet. Wir werden diesen Tag, den 10. August 2004, mit Ihnen und Ihrem Mann Dr. Ulrich Hesse auf dem Mont Beuvray in Burgund ausgiebig feiern. Damit aber auch die Wissenschaft nicht zu kurz kommt, haben wir, Ihre Mitarbeiter und Schüler, diese Ausgabe der Leipziger online-Beiträge zur Ur- und Frühgeschichtlichen Archäologie erstellt