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Events on Tuesday, February 16th, 2016

Astronomy Colloquium
Compact Neutron Star Binary Assembly n the Universe
Time: 12:00 pm - 1:00 pm
Place: 4421 Sterling Hall, SPECIAL LUNCH TALK
Speaker: Enrico Ramirez-Ruiz, UC Santa Cruz
Abstract: The existence of a population of compact neutron star binaries serves as a unique probe of general relativity and of binary stellar evolution. Mergers of neutron star binaries are promising sources for the detection of gravitational radiation. Yet, to inspiral and merge in less than a Hubble time, a compact binary must be separated by less than the radii of its main sequence progenitors. To reach their current small separations, these binaries must have passed through a common envelope phase. Reconciling the observed distribution of neutron star masses in binaries with theories of accretion during common envelope has posed a long-standing problem. This talk explores the hydrodynamics of common envelope with the goal of reconciling theories for the formation of neutron stars in close binaries with the narrow observed distribution of neutron star masses.<br>
Host: Professor D'Onghia
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Chaos & Complex Systems Seminar
The dynamics of message-carrying between combatants
Time: 12:05 pm - 1:00 pm
Place: 4274 Chamberlin Hall (Refreshments will be served)
Speaker: Joe Elder, UW Department of Sociology
Abstract: Combatants have sometimes tried to communicate with each other through neutral channels such as Quakers. This presentation will analyze Quaker message-carrying efforts between combatants in India, Pakistan, Korea, and Sri Lanka, highlighting the limitations, possibilities, and risks of such message carrying.<br>
Host: Sprott
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Theory Seminar (High Energy/Cosmology)
The Unnatural (or Split) Composite Higgs
Time: 3:30 pm - 4:30 pm
Place: 5280 Chamberlin Hall
Speaker: Tony Gherghetta, University of Minnesota
A simple way to trivially satisfy precision-electroweak and flavor constraints in composite Higgs models is to require a large global symmetry breaking scale, f > 10 TeV. This leads to a tuning of order 10^-4 to obtain the observed Higgs mass, but gives rise to a 'split' spectrum where the strong-sector resonances with masses greater than 10 TeV are separated from the pseudo Nambu-Goldstone bosons, which remain near the electroweak scale. To preserve gauge-coupling unification (due to a composite top quark), the symmetry breaking scale satisfies an upper bound f < 100-1000 TeV, which implies that the resonances are not arbitrarily heavy and may be accessible at future colliders. Furthermore, by identifying dark matter with a pseudo Nambu-Goldstone boson, the smallest coset space containing a stable, scalar singlet and an unbroken SU(5) symmetry is SU(7) / SU(6) x U(1). Interestingly, this coset space also contains a metastable color-triplet pseudo Nambu-Goldstone boson that can decay via a displaced vertex when produced at colliders, leading to a distinctive signal of unnaturalness.
Host: Yang Bai
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