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Events During the Week of December 18th through December 25th, 2022

Sunday, December 18th, 2022

Academic Calendar
Final exams
Abstract: *Note: actual end time may vary.* URL:
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Academic Calendar
Winter Commencement
Time: 10:00 am
Abstract: URL:
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Monday, December 19th, 2022

Academic Calendar
Final exams
Abstract: *Note: actual end time may vary.* URL:
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Tuesday, December 20th, 2022

Academic Calendar
Final exams
Abstract: *Note: actual end time may vary.* URL:
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Network in Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) Seminar
Towards Powerful Probes of Neutrino Self-Interactions in Supernovae
Time: 2:00 pm
Place: Join Zoom Meeting Meeting ID: 912 3071 4547
Speaker: Po-Wen Chang , CCAPP, Ohio State University
Abstract: Neutrinos remain mysterious. As an example, enhanced
self-interactions (νSI) are allowed by laboratory, cosmology, and
astrophysics data, and are frequently invoked to explain anomalies. In
this talk, I will briefly review the current probes of νSI. I will
then discuss the potential interplay between νSI and supernova
neutrinos. For the high neutrino densities within core-collapse
supernovae, νSI could be important, but robust observables have been
lacking. We show that νSI makes supernova neutrinos form a tightly
coupled fluid that expands under relativistic hydrodynamics. The
outflow becomes either a burst or a steady-state wind; which occurs
here is uncertain. Though the diffusive environment where neutrinos
are produced may make a wind more likely, further work is needed to
determine when each case is realized. In the burst-outflow case, νSI
increases the duration of the neutrino signal, and even a simple
analysis of SN 1987A data has powerful sensitivity. For the
wind-outflow case, we outline several promising ideas that may lead to
new observables. Combined, these results are important steps towards
solving the 35-year-old puzzle of how νSI impacts supernovae.
Host: Baha Balantekin
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Theory Seminar (High Energy/Cosmology)
Title to be announced
Time: 4:00 pm
Place: Chamberlin 5280
Speaker: To Be Determined
Host: George Wojcik
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Wednesday, December 21st, 2022

Academic Calendar
Final exams
Abstract: *Note: actual end time may vary.* URL:
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Preliminary Exam
Valley splitting and alloy disorder in Si/SiGe quantum dots
Time: 10:30 am
Place: Chamberlin 4274 or (passcode 630477)
Speaker: Merritt Losert, Physics Graduate Student
Abstract: Silicon/silicon-germanium heterostructures have many important advantages for hosting spin qubits. However, controlling the energy splitting between the two low-energy conduction-band valley states remains a critical challenge for scaling up to large numbers of reliable and reproducible qubits. Broad distributions of valley splittings are commonplace, even among quantum dots on the same device. Such behavior has previously been attributed to imperfections such as steps at the quantum well interface, which are known to strongly suppress the valley splitting. Many heterostructure designs have been proposed to boost the valley splitting, to overcome this problem. In this talk, we explore a simple, universal theory of valley splitting based on the reciprocal-space profile of the quantum-well confinement potential, which can explain the effects of steps, wide interfaces, alloy disorder, and custom heterostructure designs. We use this understanding to theoretically characterize the valley splitting in a variety of heterostructures, finding that alloy disorder causes substantial variations of the valley splitting, even in the absence of steps. Using this understanding, we lay out two approaches to engineer large valley splittings: one based on deterministically increasing the Fourier component of the quantum well potential that couples the valleys, and one that takes advantage of disorder to statistically increase the valley splitting.
Host: Mark Friesen
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NPAC (Nuclear/Particle/Astro/Cosmo) Forum
Looking for new physics in rare and novel processes at the LHC
Time: 2:30 pm
Place: 4274 Chamberlin Hall & Zoom:
Speaker: Saptaparna Bhattacharya, Northwestern University
Abstract: The collection of a large dataset at the Large Hadron Collider (LHC) allows for the exploration of rare processes predicted by the Standard Model of Particle Physics. In this talk I will focus on the observation of triboson production with data collected by the CMS detector at a center of mass energy of 13 TeV using the complete Run II dataset. Triboson events are rare and feature novel topologies. I will provide a historical context for the first observation of tribosons at the LHC and discuss prospects for this analysis as we head toward Run III and the high luminosity-LHC. Given the absence of any significant sign of new physics at the LHC, an effective field theory (EFT) approach which posits that the source of new physics are heavy fields beyond our current reach, can be used to indirectly look for new physics. I will state how the newly observed triboson processes can be used as a probe for new physics using the EFT framework.
Host: Sridhara Dasu
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Thursday, December 22nd, 2022

Academic Calendar
Final exams
Abstract: *Note: actual end time may vary.* URL:
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Friday, December 23rd, 2022

Academic Calendar
Graduate School Fall 2022: Master&#39;s degree deadline
Time: 4:00 pm
Abstract: CONTACT: 262-2433, gsacserv@grad.wisc.edu
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Saturday, December 24th, 2022

No events scheduled

Sunday, December 25th, 2022

Academic Calendar
Graduate School Fall 2022: Doctoral degree deadline
Time: 11:55 pm
Abstract: Degree candidates must complete all steps: CONTACT: 262-2433, gsacserv@grad.wisc.edu
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