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Events on Friday, September 13th, 2013

Theory Seminar (High Energy/Cosmology)
A simple, yet subtle, invariance of the two body decay
Time: 2:00 pm
Place: 5280 Chamberlin Hall
Speaker: Roberto Franceschini, University of Maryland
Abstract: In this talk I shall review common issues in the reconstruction of Lorentz invariants of the two body decay, in particular the problems that arise when the boost connecting the rest frame of the decaying particle and the observer (laboratory) frame is not known.
I shall discuss how certain Lorentz _variant_ quantities such as the Energy of one of the decay product encodes Lorentz _invariant_ quantities of the decay in a simple and measurable way. I will describe a method to access these invariants that allow to determine the mass of the decaying particle by observing only one of the two decay products. Not requiring the observation of both decay products, the described method can be applied when traditional quantities as the invariant mass cannot be used. I shall show concrete results about mass measurements for the leptonic decay of the top quark and supersymmetric decay chains of the gluino. Possible uses of this observation to study the stabilization symmetry of the Dark Matter at colliders will be discussed as well.
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Physics Department Colloquium
Project Poltergeist, a Ghostly Neutrino and a Specter
Time: 3:30 pm
Place: 2241 Chamberlin Hall (coffee at 4:30 pm)
Speaker: Patrick Huber, Virginia Polytechnic Institute & State University
Abstract: It is not quite Halloween yet... In this talk we will discuss how
Project Poltergeist shaped neutrino physics for decades to come and made nuclear reactors the workhorse of early oscillation searches. A renaissance of reactor neutrino experiments around 2010 lead to the very precise measurement of one of the mixing parameters, theta13 -- in the run-up to this measurement flux calculations from the 1980's were scrutinized and surprisingly the flux was found to be higher than previously expected leading to the so-called reactor anomaly. The reactor anomaly points a type of neutrino even more elusive than regular neutrinos, the ghostly sterile neutrino. We will review the calculations performed so far and highlight some of the open questions. In the final part of the talk we will point out how current attempts to settle the question of the sterile neutrino will impact our future ability to use neutrinos to peer into the cores of nuclear reactors to safeguards against the diversion of plutonium, which may play an important role in banishing the specter of nuclear terrorism.
Host: Everett
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