Studies on the polarization transfer coefficients C_x and C_z in the gamma p -> K^+ Lambda(1520,3/2^-) reaction process

We investigate the polarization transfer coefficients C_(x,z) for the gamma p -> K^+ Lambda(1520,3/2^-) reaction process, in which the photon is polarized circularly and the Lambda(1520,3/2^-) along the x- or z-axis. To this end, we employ the effective Lagrangian method at tree level and the gauge-invariant form factor scheme. In addition to the Born terms, (s,u,t_K,t_K^*)-channels and contact term, we include the nucleon resonance D_{13}(2080) in the s-channel. We compute the C_(x,z) as functions of theta_K as well as E_cm. It turns out that the K^*-exchange and D_{13} contributions are negligible within available experimental and theoretical inputs for them. In contrast, we observe that the contact and K-exchange contributions play dominant roles for determining the C_(x,z). Especially, the $K$-exchange enhances the transverse polarization transfer C_x considerably.Comment: 11 pages, 13 figure

Interaction Between Trade and Competition: Why a Multilateral Approach for the United States?

This thesis consists of two essays and an introduction. The main theme is technological knowledge that is not based on the natural sciences.The first essay is about rules of thumb, which are simple instructions, used to guide actions toward a specific result, without need of advanced knowledge. Knowing adequate rules of thumb is a common form of technological knowledge. It differs both from science-based and intuitive (or tacit) technological knowledge, although it may have its origin in experience, scientific knowledge, trial and error, or a combination thereof. One of the major advantages of rules of thumb is the ease with which they can be learned. One of their major disadvantages is that they cannot easily be adjusted to new situations or conditions. Engineers commonly use rules, theories and models that lack scientific justification. How to include these in introductory technology education is the theme of the second essay. Examples include rules of thumb based on experience, but also models based on obsolete science or folk theories. Centrifugal forces, heat and cold as substances, and sucking vacuum all belong to the latter group. These models contradict scientific knowledge, but are useful for prediction in limited contexts where they are used when found convenient. The role of this kind of models in technology education is the theme of the second essay. Engineers’ work is a common prototype for pupils’ work with product development and systematic problem solving during technology lessons. Therefore pupils should be allowed to use the engineers’ non-scientific models when doing design work in school technology. The acceptance of these could be experienced as contradictory by the pupils: a model that is allowed, or even encouraged in technology class is considered wrong when doing science. To account for this, different epistemological frameworks must be used in science and technology education. Technology is first and foremost about usefulness, not about the truth or even generally applicable laws. This could cause pedagogical problems, but also provide useful examples to explain the limitations of models, the relation between model and reality, and the differences between science and technology.QC 20111118</p