High Energy Theory Lunchtime Seminar

semester, 2018


Friday, January 26th 2018
Speaker: Jorn Kersten (Bergen U., Norway)
Subject: Late Kinetic Decoupling and Self-Interacting Dark Matter

The cosmological LambdaCDM standard model faces some problems related to the formation of structures at relatively small scales, most notably the missing-satellites problem, the cusp-core problem, the too-big-to-fail problem, and the diversity problem. I will advertise late kinetic decoupling of dark matter as a mechanism to address the missing satellites problem. Afterwards, I will describe a model involving self-interacting dark matter and sterile neutrinos that can tackle all four small-scale problems.


Friday, February 2nd 2018
Speaker: Liliana Velasco-Sevilla (Bergen U., Norway)
Subject: How multi-Higgs Physics Could Uncover the Nature of Flavour

Friday, February 9th 2018
Speaker: Robert Lasenby (Perimeter)
Subject: Searching for Weakly Coupled New Particles with Stellar Cooling

Many theories of beyond Standard Model physics include new light, weakly-coupled particles, which can be challenging to search for experimentally. The high densities and temperatures in stellar cores allow them to produce such particles in large numbers, while the large volume to surface area ratio of stars enhances the relative effects of such production on stellar energy transfer and cooling. This makes stellar observations into a sensitive probe of new particles. I’ll describe how the plasma environment in stellar cores can parametrically alter the rates for these processes, and how this can significantly change the constraints and discovery potential for some new particle candidates. I’ll also discuss some other situations where in-medium effects are important in the search for weakly-coupled new physics.


Friday, February 16th 2018
Speaker: No seminar this week

Friday, February 23rd 2018
Speaker: Daniel Chung (U. Wisconsin, Madison)
Subject: Searching for Axionic Blue Isocurvature Perturbations

If the Peccei-Quinn symmetry breaking field is displaced from its minimum
during inflation, the axion isocurvature spectrum is generically strongly
blue tilted with a break transition to a flat spectrum. A test of this
scenario with the Planck and BOSS DR11 data will be presented. Encouraging
results and its implications for future probes of axions and inflationary
cosmology will be discussed.


Friday, March 2nd 2018
Speaker: Andrew Spray, (IBS, Daejon, Korea)
Subject: TBA

Friday, March 9th 2018
Speaker: Stephen Martin (Northern Illinois U.)
Subject: TBA

Friday, March 16th 2018
SPRING BREAK - No seminar this week

Friday, March 23rd 2018
Speaker: Gokce Basar (U. Illinois, Chicago)
Subject: TBA

Friday, March 30th 2018
Speaker: Hooman Davoudiasl (Brookhaven)
Subject: TBA

Friday, April 6th 2018
Speaker: TBA
Subject: TBA

Friday, April 13th 2018
Speaker: Kristian Jensen (San Francisco State U.)
Subject: TBA

Friday, April 20th 2018
Speaker: Nobuchika Okada (U. Alabama)
Subject: TBA

Friday, April 27th 2018
Speaker: Mustafa Amin (Rice U)
Subject: TBA

Friday, May 4th 2018
Speaker: Yanou Cui (U. California, Riverside)
Subject: Cosmic Archaeology with Gravitational Waves from Cosmic Strings

Cosmic strings are generic cosmological predictions of many extensions
of the Standard Model of particle physics, such as a U(1) symmetry breaking phase transition in the early universe or remnants of superstring theory. Unlike other topological defects, cosmic strings can reach a scaling regime that maintains a small fixed fraction of the total energy density of the universe from a very early epoch until today. If present, they will oscillate and generate gravitational waves with a frequency spectrum that imprints the dominant sources of total cosmic energy density throughout the history of the universe. In this talk I will demonstrate that current and future gravitational wave detectors, such as LIGO and LISA, could be capable of measuring the frequency spectrum of gravitational waves from cosmic strings and discerning the energy composition of the universe at times well before primordial nucleosynthesis and the cosmic microwave background where standard cosmology has yet to be tested. This work establishes a benchmark case that gravitational waves may provide an unprecedented, powerful tool for probing the evolutionary history of the very early universe.

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