The 2007 Golden lion tamarin conference Abstracts


Alireza Rafiee

Quasar lifetime and Black Hole Spin Quasars seem to have a limited lifetime
They continuously accrete matter and gain angular momentum but the increase on radiative efficiency of that system remains limited to a physical upper bound. Using that physical barrier, we have estimated an upper limit for quasar lifetime.

Steve Beale

Measuring Bs mixing at the Fermilab Tevatron
Neutral Bs mesons (b-bar s) will spontaneously transform into their anti-particle (and visa versa) by a weak process known as mixing. Measurement of the mixing frequency provides an important constraint on the electroweak coupling of s and d quarks with the top quark. Presently, the only place where this measurement can be made is at the Fermilab Tevatron, a proton-antiproton collider with a center of mass energy of 1.96 TeV. The D0 detector is one of two collider detectors at Fermilab currently working to make this measurement. After a short overview of the Tevatron, the D0 Detector, and general mixing phenomenology, I will present the latest mixing measurement from D0.

Tzahi Yavin

Modelling Markets
In the last quarter of a century or so, the sophistication of the mathematical modeling of financial markets has witnessed a tremendous increase. In this talk I will briefly discuss one of the corner stones in this field, the Black-Scholes model, and how it is used to price options for stocks trading on the stock exchange.

Yan Sun

Density functional study of 13-atom transition-metal clusters and bimetallic A_4B_12 clusters

Min zhang

Global optimization of 13-atom 5d transition metals
We did structural global optimization for six 5d transition metals(Ta-Pt). Two optimization algorithms, Tabu Search in Descriptor Space(TSDS) and Simulated annealing (SA), were used and their performances were compared. Energy evaluation was done with PBE exchange-correlation functional implemented by VASP. Due to complexity of the multiplicities of transition metals, we did calculations with full relaxation of multiplicity. Amazingly, we found none of them had an icosahedral ground state structure. We compared thoroughly our results with previously reported structures. Calculations show that our results are the best. To rule out the difference could be introduced by choice of functional, we did local optimization for our results and structures reported by other researchers with LDA and PW91. The LDA and PW91 functionals give similar results to PBE and confirm that we found the best structures to date for these clusters.

Brynle Barrett

Interferometric Measurement of the Fine Structure Constant using Cold Rubidium
Atoms in an Atomic Fountain One of the most challenging questions in astrophysics today is to establish when and how the universe became (re)ionized. Although it is accepted that the overall process is well understood, and in spite of the observational and theoretical progress that have been made in the last few years, there are still many details that remain controversial and unsolved. At a redshift z ~ 6 we are approaching to the end of Epoch of Reionization, but the number of known quasars and galaxies close to this redshift is still very low, thus the uncertainties are large. To improve our knowledge of that fundamental epoch we need to find more high redshift sources. Here, I will briefly summarize some of the basic ideas on this topic and present the description of the data we are working on and the procedure we have followed.

Edward Ackad

Supercritical Collisions with no intial electrons Colliding two fully ionized
Uranium atoms can lead to pair creation, but solving for a collision with no initial electrons is not commonly done. I will show how it is possible to solve for this system and show results of current work were we can show the enhancement of the positron production due to the decay of supercritical resonance state for collisions with some nuclear sticking.