Events at Physics

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Events During the Week of December 5th through December 12th, 2021

Monday, December 6th, 2021

No events scheduled

Tuesday, December 7th, 2021

Network in Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) Seminar
Dark lepton superfluid in proto-neutron stars
Time: 2:00 pm
Place: Meeting ID: 994 6425 2867
Speaker: Dake Zhou , University of California, Berkeley and Northwestern University
Abstract: I will discuss how sub-GeV neutrino portal bosons that carry lepton number can condense inside a proto-neutron star (newly born neutron star). These bosons are produced copiously and form a Bose-Einstein condensate for a range of as yet unconstrained coupling strengths to neutrinos. The condensate is a lepton number superfluid with transport properties that differ dramatically from those encountered in ordinary dense nuclear matter. I will discuss how this phase of matter could alter the evolution of proto-neutron stars and comment on the implications for neutrino signals and nucleosynthesis. Time: December 7, 2021 2:00 PM Meeting ID: 994 6425 2867
Host: Baha Balantekin
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Wednesday, December 8th, 2021

Physics ∩ ML Seminar
Genetic algorithms and breeding branes
Time: 11:00 am - 12:00 pm
Place: 5280 Chamberlin Hall
Speaker: Gregory Loges, UW Madison
Abstract: Taking inspiration from nature, genetic algorithms provide an approach to optimization which mimics aspects of natural selection. Breeding, mutation, and ‘survival of the fittest’ all drive a population of individuals, generation by generation, towards their fittest form. In this talk I will present an introduction to genetic algorithms and discuss ongoing work utilizing genetic algorithms to search for consistent intersecting brane models.
Host: Moritz Muenchmeyer
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Theory Seminar (High Energy/Cosmology)
The cosmological moduli problem and naturalness
Time: 1:00 pm - 2:00 pm
Place: Chamberlin 5280
Speaker: Robert Wiley Deal, University of Oklahoma and University of Wisconsin-Madison
Abstract: We examine the cosmological moduli problem and its connection to electroweak naturalness. The cosmological moduli problem (CMP) comes in three parts: 1. Potential violation of Big-Bang nucleosynthesis (BBN) constraints from late decaying moduli fields, 2. The moduli-induced gravitino problem wherein gravitinos are overproduced and their decay violates BBN or dark matter overproduction bounds, and 3. The moduli-induced lightest SUSY particle (LSP) overproduction problem. We calculate the various two-body decay widths of a light modulus field into MSSM particles and gravitinos within general supersymmetric models. We evaluate regions of gravitino mass vs modulus mass parameter space constrained by BBN, by overproduction of gravitinos, and by overproduction of neutralino dark matter, along with connections to naturalness. We introduce a new solution to the CMP, and list a variety of other solutions to the CMP.
Host: Lars Aalsma
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Thursday, December 9th, 2021

Astronomy Colloquium
Winds of Change around Black Holes
Time: 3:30 pm - 5:00 pm
Place: 4421 Sterling Hall, Coffee and cookies 3:30 PM, Talk begins at 3:45 PM
Speaker: Greg Sivakoff, University of Alberta
Abstract: Accretion disks, where matter with angular momentum spirals down through a disk, occur around objects ranging from the youngest stars to supermassive black holes. But not all of this material reaches the center of the disk. Instead, some material is accelerated away from the disk. These outflows can be ejected in a narrow opening angle (what astronomers call "jets") or can be relatively unfocused (what astronomers call “winds”). While we do not know the precise processes that accelerate and collimate winds and jets, magnetic fields almost certainly play a key role. My team and I study black hole X-ray binaries, stellar-mass black holes accreting from a nearby star. We combine observations across the electromagnetic spectrum to learn about the physics of accretion and jets. In this talk, I will discuss how we have revealed two new windows onto the physics of inflows and outflows in X-ray binaries: fast variability measured across the electromagnetic spectrum (which provides the potential to accurately identify the accretion physics that launch relativistic jets) and the modelling of changes in the X-ray brightness of black hole X-ray binaries (which implies that strong winds from the accretion disk are universal). With the advent of new and upcoming facilities, we have a huge potential to take advantage of these winds of change in the next decade.
This will be a version of the lectures I gave in 2020 on the Canadian Association of Physicists Lecture Tour, making it well suited for undergraduates to attend.
Host: Professor Sebastian Heinz
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Friday, December 10th, 2021

Graduate Introductory Seminar (Physics 701)
Broader impacts through outreach: your key to an NSF fellowship
Time: 12:05 pm - 12:55 pm
Place: 2241 Chamberlin
Speaker: Mallory Conlon, UW Madison Department of Physics
Host: Sridhara Dasu
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Physics Department Colloquium
Holiday Colloquium
Time: 3:30 pm - 4:30 pm
Place: 2103 Chamberlin Hall
Speaker: 2019 Physics Ph.D. Cohort, UW-Madison
Host: 2019 Physics Ph.D. Cohort
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