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Events During the Week of April 25th through May 2nd, 2010

Monday, April 26th, 2010

NPAC (Nuclear/Particle/Astro/Cosmo) Forum
Joint with High Energy
Cosmic Rays and the Quest for New Physics
Time: 4:00 pm
Place: 4274 Chamberlin
Speaker: Stefano Profumo, U.C. Santa Cruz
Abstract: Recent cosmic ray data, notably from the Pamela and Fermi satellites, indicate that previously unaccounted-for powerful sources in the Galaxy inject high-energy electrons and positrons. Interestingly, this new source class might be related to new fundamental particle physics, and specifically to pair-annihilation or decay of galactic dark matter. I will
discuss how this exciting scenario is constrained by Fermi gamma-ray observations, and which astrophysical source counterparts could also be responsible for the high-energy electron-positron excess. In particular, I will review the case for nearby mature pulsars, and the impact of newly
discovered radio-quiet pulsars that pulsate in gamma rays. While
high-energy electron-positron measurements sample local (closer than 1 kpc) cosmic rays, diffuse radio and gamma-ray emission informs us about the global galactic cosmic ray population. I will thus offer a few thoughts on recent claims involving the detection of diffuse radio ("WMAP haze") and gamma-ray ("Fermi haze") emissions and on implications for the quest for New Physics
Host: Michael Ramsey-Musolf
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Tuesday, April 27th, 2010

Chaos & Complex Systems Seminar
Title to be announced
Time: 12:05 pm
Place: 4274 Chamberlin Hall
Speaker: Ananth Seshadri, UW-Madison, Dept. of Economics
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Astronomy Colloquium
The Nova Outburst: Evidence for a New Paradigm?
Time: 3:30 pm - 5:00 pm
Place: 3425 Sterling Hall
Speaker: Dr. Robert Williams, STSci
Abstract: Spectroscopic observations of novae date back a century and the fundamental nature of the outburst has been understood for 50 years. Yet, recent observations suggest a possible significant modification to the standard nova paradigm. A high-resolution spectroscopic survey of novae has revealed short-lived heavy element absorption systems near maximum light consisting of Fe-peak and s-process elements. The spectroscopic evolution of novae is interpreted in terms of two distinct interacting gas systems in which the bright continuum is produced by the outburst ejecta but absorption and emission lines originate in gas ejected by the secondary star in a way that could explain dust formation and X-ray emission from novae. The absorbing gas is circumbinary and it pre-exists the outburst. Its origin appears to be mass ejection from the accretion disk or secondary star, and it might initiate novae outbursts.
Host: Professor Richard Townsend
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Wednesday, April 28th, 2010

No events scheduled

Thursday, April 29th, 2010

R. G. Herb Condensed Matter Seminar
Can the Moon affect entanglement transfer?
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Joseph H. Eberly, University of Rochester
Abstract: Surprises have emerged from studies of entanglement evolution in quantum theory, and counter-intuitive predictions [1] have been confirmed in experiment [2]. It is implicit in most analyses of entanglement evolution that the observer is all-powerful and able to determine a system state completely, but this is usually not true. One reason is that all aspects of a party's quantum state typically cannot be identified. Unknown and non-interacting external parties are typically not mentioned, excluded from view even if entangled with the system of interest. We will refer to this always-present but hidden and non-interacting background universe as the "Moon", and will present a sample sketch showing the effect of this Moon on entanglement evolution.

[1] See the review: T. Yu and J.H. Eberly, Science 323, 598 (2009).

[2] M. P. Almeida, F. de Melo, M. Hor-Meyll, A. Salles, S.P. Walborn, P.H. Souto-Ribeiro and L. Davidovich, Science 316, 579 (2007).
Host: Robert Joynt
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NPAC (Nuclear/Particle/Astro/Cosmo) Forum
Many-body high energy QCD: from wee partons to the perfect fluid
Time: 4:00 pm
Place: 4274 Chamberlin
Speaker: Raju Venugopalan, Brookhaven National Laboratory
Abstract: A high energy hadron can be visualized as a Lorentz contracted core of valence partons accompanied by a furry sea of wee partons. The many-body properties of these wee
partons and their evolution with energy can be described by a weak coupling effective field theory called the Color Glass Condensate (CGC). Novel factorization theorems allow us to understand quantitatively the early time
dynamics of heavy-ion collisions when two CGCs shatter forming a classical fluid called the Glasma. We discuss the properties of this Glasma and some of its experimental manifestations in heavy-ion collisions.
If time permits, we shall outline outstanding conceptual issues in understanding the evolution of the Glasma into the Quark-Gluon Plasma.
Host: Michael Ramsey-Musolf
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Friday, April 30th, 2010

NPAC (Nuclear/Particle/Astro/Cosmo) Forum
Joint with Phenomenology
A Lattice Calculation of QCD Critical Point from Canonical Ensemble
Time: 2:30 pm
Place: 5280 Chamberlin
Speaker: Keh-Fei Liu, University of Kentucky
Abstract: At zero chemical potential, the finite temperature transition of QCD is known to be a smooth crossover from lattice simulations. The conjectured first order phase transition and its critical point at finite density is of great theoretical and experimental interest.
I will review the status of the lattice calculation with grand canonical approach and present an algorithm in the canonical approach. The preliminary results on the identification of a first order transition and the determination of the critical point with the help of Maxwell construction will be reported.
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Physics Department Colloquium
Plasma Turbulence in the Solar Wind
Time: 4:00 pm
Place: 2241 Chamberlin Hall (coffee at 3:30 pm)
Speaker: Bill Dorland, University of Maryland
Abstract: Gyrokinetics is a first principles theory for the dynamics and thermodynamics of magnetized, ionized gas. It has been developed over the last three decades, primarily in the magnetic confinement fusion community, where it is widely used to interpret observations and to design experimental devices and operational scenarios. Gyrokinetic simulations of instabilities and turbulence in hot, rarefied plasma have been tested carefully in these laboratory settings. Recently, gyrokinetic ideas and codes have been successfully used to interpret observations of turbulent fluctuations in the solar wind. While magnetohydrodynamics remains the appropriate theory for {it dynamics} in larger, truly astrophysical plasmas (such as galaxy cluster plasmas), the appropriate framework for the study of many interesting thermodynamic processes in astrophysics (such as turbulent heating and transport) is gyrokinetics. Example applications will be shown.
Host: Forest
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