Events at Physics

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Events During the Week of November 7th through November 13th, 2021

Monday, November 8th, 2021

No events scheduled

Tuesday, November 9th, 2021

Network in Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) Seminar
Quarkyonic model for neutron stars
Time: 2:00 pm - 3:00 pm
Speaker: Srimoyee Sen , Iowa State University
Abstract: The observed mass and radius relations of neutron stars can be explained remarkably well using a model of dense matter known as quarkyonic matter. I describe how the quarkyonic matter can arise dynamically from an excluded volume model for nuclear interactions and how thermal effects can be incorporated in such a model. I also discuss how one can improve the excluded volume model to correctly reproduce low energy nuclear interactions and recover mass radius relations of neutron stars.
Host: Baha Balantekin
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Theory Seminar (High Energy/Cosmology)
Precision Calculation of Inflation Correlators at One Loop
Time: 4:00 pm - 5:00 pm
Place: Chamberlin 5280
Speaker: Yiming Zhong, KICP
Abstract: We initiate a systematic study of precision calculation of the inflation correlators at the 1-loop level, starting in this paper with bosonic 1-loop bispectrum with chemical-potential enhancement. Such 1-loop processes could lead to important cosmological collider observables but are notoriously difficult to compute due to the lack of symmetries. We attack the problem from a direct numerical approach based on the real-time Schwinger-Keldysh formalism and show full numerical results for arbitrary kinematics containing both the oscillatory "signals" and the "backgrounds". Our results show that, while the non-oscillatory part can be one to two orders of magnitude larger, the oscillatory signal can be separated out by applying appropriate high-pass filters. We have also compared the result with analytic estimates typically adopted in the literature. While the amplitude is comparable, there is a non-negligible deviation in the frequency of the oscillatory part away from the extreme squeezed limit. See arXiv:2109.14635 for more details.
Host: Lars Aalsma
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Wednesday, November 10th, 2021

Department Meeting
CLOSED Department Meeting
Time: 12:15 pm - 1:00 pm
Place: 4274 Chamberlin Hall
Speaker: Mark Eriksson, UW - Madison
Closed meeting pursuant to Section 19.85(1)(c) of the Wisconsin Open Meetings Law Closed to all but tenured faculty to discuss faculty personnel matters. Closed to all but tenured faculty. NOTE LOCATION, 4274 CH.
Host: Mark Eriksson
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Thursday, November 11th, 2021

Astronomy Colloquium
The fate of the merger remnant in GW170817 and its imprint on the jet structure
Time: 3:30 pm - 5:00 pm
Place: 4421 Sterling Hall, Coffee and Cookies at 3:30 pm, Talk starts at 3:45 pm
Speaker: Ariadna Murguia Berthier, UCSC/CIERA
Abstract: On August 17, 2017, LIGO/Virgo detected the first gravitational waves from merging neutron stars. This event, known as GW170817 was accompanied by observations all over the electromagnetic spectrum. The peculiar gamma-ray burst that followed the merger in GW170817, is unlike any gamma-ray burst observed before. In order to explain the afterglow observations, there is a need for the jet launched after the merger to have structure, which is a natural consequence of the interaction of the jet with the ambient medium. In this talk, I will show special relativistic simulations of the interaction of the jet with several outflows launched during the merger and compare the simulations to the observation. I will then use the results in order to constrain key properties of the merger, such as the delay time between the merger and the collapse to a black hole.

We strongly encourage you to attend the colloquium in person. If that is impossible, it is available over zoom at the following link:

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Friday, November 12th, 2021

Graduate Introductory Seminar (Physics 701)
Atomic, molecular, and optical physics research overview
Time: 12:05 pm - 12:55 pm
Place: 2241 Chamberlin
Speaker: Shimon Kolkowitz, UW Madison Department of Physics
Host: Sridhara Dasu
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Physics Department Colloquium
The naturalness issue and weak scale supersymmetry in the LHC era
Time: 3:30 pm - 4:30 pm
Place: 2103 Chamberlin Hall
Speaker: Howard Baer, University of Oklahoma
Abstract: Weak scale supersymmetry (SUSY) has been, for many years, the dominant paradigm for physics beyond the Standard Model and in fact the simplest model predicted the Higgs mass to lie exactly in the range where it was discovered. And yet the community seems discouraged as to the likelihood of SUSY due to lack of superpartners at LHC and the somewhat large value of the Higgs mass: these are thought to exacerbate the ``naturalness'' question. A more nuanced evaluation of electroweak naturalness points to a highly natural SUSY mass spectrum characterized by light Higgsino states with mass ~100-300 GeV while the SUSY breaking scale lies in the multi-TeV region. Such a spectrum of superparticles seems to emerge from simple statistical ideas applied to the string theory landscape of vacua. The natural SUSY particle mass spectrum 1. gives rise to distinctive SUSY signatures at LHC but 2. might also allow SUSY to escape LHC detection so that a higher energy hadron collider may be needed. The required light higgsino states should appear at an e+e- collider operating at CM energy 400-600 GeV: the International Linear Collider or ILC. Requiring naturalness also in the QCD sector, one expects two dark matter particles: the axion along with a higgsino-like neutralino where typically the axion makes up the bulk of dark matter. Detection of a higgsino-like WIMP is ultimately expected while the axion would have a suppressed coupling to photons which makes its detection more challenging than was previously expected.
Host: Vernon Barger
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