Search for the Higgs boson in the gamma gamma final state at the Tevatron

We present searches for Higgs bosons decaying to the di-photon final state using up to 5.4/fb of data at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. Whilst the branching ratio to the di-photon final state is small in the Standard Model, this channel contributes appreciably to the overall Higgs sensitivity at the Tevatron. In parallel, the limit is re-interpreted in fermiophobic models where the di-photon branching ratio is considerably larger. This decay channel will be of major importance in the light mass Standard Model Higgs search at the LHC.Comment: 5 pages, 3 figures, to appear in the proceedings of "35th International Conference of High Energy Physics - ICHEP2010

What Is the Function of Confirmation Bias?

Confirmation bias is one of the most widely discussed epistemically problematic cognitions, challenging reliable belief formation and the correction of inaccurate views. Given its problematic nature, it remains unclear why the bias evolved and is still with us today. To offer an explanation, several philosophers and scientists have argued that the bias is in fact adaptive. I critically discuss three recent proposals of this kind before developing a novel alternative, what I call the ‘reality-matching account’. According to the account, confirmation bias evolved because it helps us influence people and social structures so that they come to match our beliefs about them. This can result in significant developmental and epistemic benefits for us and other people, ensuring that over time we don’t become epistemically disconnected from social reality but can navigate it more easily. While that might not be the only evolved function of confirmation bias, it is an important one that has so far been neglected in the theorizing on the bias

Concrete renovation and enhancing of fire protection of an existing tunnel with sprayable polymer cement concrete (SPCC)

The approx. 342 m long tunnel located in the old town is constructed as a two cell rectangular frame section as part of the L530 in Lüdenscheid in 1971. During the stocktaking process it was detected that the demands of technical standards like e.g. RBT, ZTV-ING, RIZ-ING are not met. The construction also lacks of the structural fire protection. A recalculation of the rectangular frame section in case of exposure to fire showed that there is no sufficient load capacity. Due to the location in the city center with construction work above the tunnel line this topic is of major concern. Furthermore the need of concrete renovation was obtained, e.g. cracks, defects in the concrete, chlorides and in insufficient concrete cover. For the concrete renovation and the enhancing of fire protection it is planned to apply a sprayable polymer cement (spcc) to an extensive area. The report describes the calculatory verifications of the fire case and the intended renovation and enhancing concept

An ellipsometer with variable angle of incidence for studies in ultrahigh vacuum

The windows for the vacuum chamber are incorporated into the optical bench system by means of flexible bellows which allow measurements to be made over a large range of angle of incidence, one of which is chosen so that maximum sensitivity is obtained. The principal angle of incidence was determined, and straightforward corrections for strain birefringence of vacuum chamber windows were made. Atomically clean surfaces of sodium chloride and lithium fluoride were investigated to verify the performance of the system. Submonolayer and monolayer coverage of water on these surfaces could be detected. On cleavage planes of NaCl, a first monolayer of adsorbed water is complete at about one torr only

A hybrid model for chaotic front dynamics: From semiconductors to water tanks

We present a general method for studying front propagation in nonlinear systems with a global constraint in the language of hybrid tank models. The method is illustrated in the case of semiconductor superlattices, where the dynamics of the electron accumulation and depletion fronts shows complex spatio-temporal patterns, including chaos. We show that this behavior may be elegantly explained by a tank model, for which analytical results on the emergence of chaos are available. In particular, for the case of three tanks the bifurcation scenario is characterized by a modified version of the one-dimensional iterated tent-map.Comment: 4 pages, 4 figure