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Events During the Week of April 3rd through April 10th, 2016

Monday, April 4th, 2016

No events scheduled

Tuesday, April 5th, 2016

Chaos & Complex Systems Seminar
Toward an atlas of the physical internet
Time: 12:05 pm - 1:00 pm
Place: 4274 Chamberlin Hall (refreshments will be served)
Speaker: Paul Barford, UW Department of Computer Sciences
Abstract: The availability of accurate and timely maps of the Internet would be a compelling starting point for diverse research topics such as assessing infrastructure vulnerabilities, understanding routing behavior, and analyzing application performance. However, despite the many and varied efforts over the years, there remains no central repository of accurate Internet maps. In this talk, I will describe the challenges in assembling maps of Internet topology based on standard data sources. I will also describes Internet Atlas, a repository and visualization portal of the physical interconnection structure of the Internet that has been under construction at the University of Wisconsin for four years. Atlas currently contains PoP/colo and link location data for over 1K networks (including all tier 1 providers) around the world. The Atlas repository was the starting point for our recent study of Internet long haul infrastructure. I will describe key results from that study on deployment characteristics and risks in US long haul infrastructure, and opportunities to improve performance and robustness.
Host: Clint Sprott
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Theory Seminar (High Energy/Cosmology)
Lepton Jets from Radiating Dark Matter
Time: 3:30 pm
Place: 5280
Speaker: Malte Buschmann, Fermilab
Abstract: The idea that dark matter forms part of a larger dark sector is very intriguing, given the high degree of complexity of the visible sector. We discuss lepton jets as a promising signature of an extended dark sector. As a simple toy model, we consider an O(GeV) DM fermion coupled to a new U(1)' gauge boson (dark photon) with a mass of order GeV and kinetically mixed with the Standard Model photon. Dark matter production at the LHC in this model is typically accompanied by collinear radiation of dark photons whose decay products can form lepton jets. We analyze the dynamics of collinear dark photon emission both analytically and numerically. In particular, we derive the dark photon energy spectrum using recursive analytic expressions, using Monte Carlo simulations in Pythia, and using an inverse Mellin transform to obtain the spectrum from its moments. In the second part, we simulate the expected lepton jet signatures from radiating dark matter at the LHC, carefully taking into account the various dark photon decay modes and allowing for both prompt and displaced decays. Using these simulations, we recast two existing ATLAS lepton jet searches to significantly restrict the parameter space of extended dark sector models, and we compute the expected sensitivity of future LHC searches.
Host: Yang Bai
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Wednesday, April 6th, 2016

Department Meeting
Time: 12:15 pm - 1:30 pm
Place: 5310 Chamberlin Hall
Host: Albrecht Karle
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Thursday, April 7th, 2016

R. G. Herb Condensed Matter Seminar
Clearly witnessing the quantum fluctuations of a mechanical oscillator
Time: 10:00 am
Place: 5310 Chamberlin Hall
Speaker: Dr. Ray Simmonds , NIST, Boulder
Can a harmonic oscillator ever be truly at rest? It may seem strange, but according to Heisenberg’s uncertainty principle, the answer is: “no!” Even at a temperature of absolute zero, in its lowest possible energy state or “ground state”, the oscillator must still exhibit quantum fluctuations of its position and momentum. Can we unambiguously detect motion of a purely quantum origin? I will discuss a unique experiment that can unequivocally observe the quantum fluctuations of a mechanical oscillator near its ground state of motion. To do this, we have created a hybrid system that merges a microwave opto-mechanical element with a superconducting quantum bit (or qubit). Parametric coupling between the electrical and the mechanical oscillators allows us to cool the mechanics to its ground state and then amplify the intrinsic quantum fluctuations in both oscillators into real energy quanta that can then be detected by the qubit, which effectively acts as an ideal single photon or phonon detector. Operated in reverse, this system could be used to prepare complex quantum states of mechanical motion or to generate entanglement between the mechanical phonons and the electrical microwave photons. Controlling the quantum states of long-lived mechanical oscillators is important for applications in quantum information and for providing new, powerful quantum-enhanced detection methods for unbeatable precision measurements.
Host: McDermott
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Cosmology Journal Club
An Informal discussion about a broad variety of arXiv papers related to Cosmology
Time: 12:15 pm - 1:15 pm
Place: 5242 Chamberlin Hall
Abstract: Please visit the following link for more details:
Please feel free to bring your lunch!
If you have questions or comments about this journal club, would like to propose a topic or volunteer to introduce a paper, please email Amol Upadhye (
Host: Amol Upadhye
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Astronomy Colloquium
'A Walk on the Warped Side: Searches for Gravitational Waves from Compact Objects in Advanced LIGO'
Time: 3:30 pm - 5:00 pm
Place: 4421 Sterling Hall, Coffee and Cookies 3:30 PM, Talk at 3:45 PM
Speaker: Sarah Caudill, UW Milwaukee - Physics Dept
Abstract: The Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) recently confirmed one of the last predictions of Albert Einstein's General Theory of Relativity, that violent astrophysical collisions create ripples in the fabric of spacetime. On September 14, 2015, a gravitational wave signal from the collision of two massive black holes reached the Earth after traveling 1.3 billion years. The detection of this signal marks the beginning of gravitational wave astronomy and promises many more exciting discoveries in the near future. In this talk, I will discuss the methods that LIGO uses to detect the collisions of binary compact objects containing neutron stars and/or black holes and report on the most recent results from these searches. Additionally, I will discuss what we can learn from these collisions regarding the nature of spacetime.

Host: Prof Elena D'onghia
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Intellectual Property, Commercialization of Innovation at UW-Madison, and an Introduction to D2P
Time: 4:30 pm - 5:30 pm
Place: 5280 Chamberlin Hall
Speaker: Robert Pozner , Discovery to Product, UW Madison
Abstract: Reviews of the types of innovation that are patentable, the patent process, and the role of patents in commercialization. A description of Discovery to Product (D2P) and it’s role in commercializing technology at UW-Madison.
Host: Duncan Carlsmith
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Friday, April 8th, 2016

Theory Seminar (High Energy/Cosmology)
Fermion masses and mixings in F-theory GUTs
Time: 2:00 pm
Place: 5280 Chamberlin Hall
Speaker: Gianluca Zoccarato, Instituto de Fisica Teorica, Madrid
Abstract: In this talk I will discuss the structure of Yukawa couplings in local SU(5) F-theory models with E7 and E8 enhancement. In these models the whole flavour structure for the MSSM charged fermions is encoded in a small region of the entire compactification space. While only one generation of quarks and leptons acquires mass after taking into account non-perturbative effects the other two families acquire a mass which is hierarchically smaller compared to the mass of the first generation.
I will show that there is a unique model embeddable both in E7 and in E8 with a good hierarchical structure for the fermion masses. Finally I will discuss the structure of the CKM matrix for this particular model.
Host: Pablo Soler
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Physics Department Colloquium
Observation of Gravitational Waves from a Binary Black Hole Merger
Time: 3:30 pm - 4:30 pm
Place: 2241 Chamberlin hall
Speaker: Daniel Holz, University of Chicago
Abstract: We will provide an overview of LIGO's first event. The signal is consistent with the merger of two black holes of 30 Msun each at a distance of 400 Mpc. We will discuss some aspects of the detection, including parameter estimation, tests of general relativity, and astrophysical constraints.
Host: Dan Chung
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