Theory Seminar (High Energy/Cosmology) |
Events During the Week of February 11th through February 18th, 2024
Monday, February 12th, 2024
- Mapping New Physics from the UV to the IR
- Time: 4:00 pm - 5:00 pm
- Place: 5280 Chamberlin Hall
- Speaker: Grant Remmen, NYU
- Abstract: Using a combination of techniques spanning the modern amplitudes program, string theory, effective field theory, cosmology, and particle physics, I will show how the space of possibilities for new physics can be constrained—from both top-down and bottom-up perspectives—in a variety of contexts, ranging from quantum gravity, to predictions for colliders, to cosmic inflation.
In the first part of the talk, we will ask a bedrock question of quantum gravity: Is string theory unique? String amplitudes famously accomplish several extraordinary and interrelated mathematical feats, including an infinite spin tower, tame UV behavior, and dual resonance. I will demonstrate that it is possible to construct infinite new classes of tree-level, dual resonant amplitudes with customizable, nonlinear mass spectra. The construction generalizes naturally to n-point scattering and allows for a worldsheet integral representation. However, these constructions can be strongly constrained using multiparticle factorization, which provides a powerful new set of tools for building consistent amplitudes. In the case of a Regge spectrum, I will investigate whether string amplitudes can be bootstrapped from first principles, finding extra freedom in the dynamics that allows for a new class of dual resonant hypergeometric amplitudes.
In the second part of the talk, I will take a particle physics-driven approach, constraining effective field theories using unitarity and causality. We will construct analytic dispersion relations for the effective field theory of the standard model, bounding the size and sign of higher-dimension operators, with significant implications for CP and flavor violation. These positivity bounds allow us to connect qualitatively different experiments, including predictions for the LHC and precision measurements. I will then apply these tools in a cosmological context, building positivity bounds for the theory of multifield inflation and extracting predictions for non-Gaussianities in the cosmic microwave background.
Taken together, these two complementary initiatives comprise a program unifying phenomenological, formal, and cosmological approaches to high energy physics, bringing together powerful tools bridging fields to map the possibilities of future physics. - Host: Lisa Everett
Tuesday, February 13th, 2024
- No events scheduled
Wednesday, February 14th, 2024
- No events scheduled
Thursday, February 15th, 2024
- Tabletop to Telescope: Unraveling the Mystery of Dark Matter
- Time: 4:00 pm - 5:00 pm
- Place: 5280 Chamberlin Hall
- Speaker: Tanner Trickle, Fermilab
- Abstract: Recent years have seen a dramatic expansion in ideas to search for dark matter beyond the WIMP paradigm. In this talk we'll discuss a diverse range of new approaches, starting with small-scale tabletop experiments. These experiments target dark matter particles far lighter than WIMPs using innovative ideas from condensed matter physics and quantum sensing. New calculations have transformed our understanding of how dark matter can interact with electrons and are essential for current experimental efforts. Additionally, we'll explore how collective excitations, e.g., phonons and magnons, can revolutionize the way we search for dark matter. Complementing these tabletop experiments, pulsar timing arrays are exceptionally sensitive to new physics on galactic scales. While their primary purpose is to detect stochastic gravitational wave backgrounds, we'll show how their extraordinary precision can be leveraged to hunt for both the lightest, and heaviest, dark matter candidates.
- Host: Lisa Everett
Friday, February 16th, 2024
- No events scheduled