Evidence for spin correlation in t ̅t production

We present a measurement of the ratio of events with correlated t and t ?t spins to the total number of t ?t events. This ratio f is evaluated using a matrix-element-based approach in 729 t ?t candidate events with a single lepton ? (electron or muon) and at least four jets. The analyzed p ?p collisions data correspond to an integrated luminosity of 5.3 fb(-1) and were collected with the D0 detector at the Fermilab Tevatron collider operating at a center-of-mass energy √s=1.96 TeV. Combining this result with a recent measurement of f in dileptonic final states, we find f in agreement with the standard model. In addition, the combination provides evidence for the presence of spin correlation in t ?t events with a significance of more than 3 standard deviations.     

A random map implementation of implicit filters

Implicit particle filters for data assimilation generate high-probability samples by representing each particle location as a separate function of a common reference variable. This representation requires that a certain underdetermined equation be solved for each particle and at each time an observation becomes available. We present a new implementation of implicit filters in which we find the solution of the equation via a random map. As examples, we assimilate data for a stochastically driven Lorenz system with sparse observations and for a stochastic Kuramoto–Sivashinsky equation with observations that are sparse in both space and time.     

Lakatos’Proofs and Refutations Comes Alive in an Elementary Classroom

This paper presents an alternative pedagogy implicit in Imre Lakatos’ Proofs and Refutations: The Logic of Mathematical Discovery. Through the voices of his characters, Lakatos reveals that learning mathematics is a discourse laden activity. In this approach it is acceptable, if not preferable, to refute a conjecture. Examples of the use of a Lakatosian approach in an elementary classroom are given. In this classroom setting students are able to propose more mature solutions, through posing and refuting conjectures.     

?therische ?le

Ohne Zusammenfassung