Current Seminars
Institute for Fundamental Science
2023-24 Academic Year
Seminars, Colloquia, and Workshops
Organizer and host: Pouya Asadi
Unless otherwise noted, IFS seminars are Mondays at 4:00 p.m. in the IFS Seminar Room, 472 Willamette Hall.
A seminar announcement is distributed via email prior to each one. To add your name to the notification list, please email your request to Claire Staley, cnstaley@uoregon.edu.
To see prior years’ seminars, click here.
Fall Term 2024
Monday, October 7 4:00 – 5:00 pm
Probing the Lifetime Frontier with the ATLAS Inner Detector
Speaker: Jackson Burzynski (Simon Fraser University)
Abstract: It is widely recognized that the Standard Model (SM) of particle physics is not a complete description of the interactions of fundamental particles. And yet, after over a decade of intense scrutiny, the experiments at the Large Hadron Collider (LHC) have produced no definitive evidence of physics beyond the SM. The vast majority of searches for beyond SM physics have targeted heavy, strongly interacting particles that decay almost instantaneously back to SM particles. However, many models propose the existence of new long-lived particles (LLPs) that can travel significant distances before decaying, yielding unconventional detector signatures that may be overlooked by common search techniques. Searches for LLPs decaying in the ATLAS inner detector (ID) are crucial for providing experimental sensitivity to a broad range of LLP lifetimes, but also must overcome challenges posed by the reconstruction of displaced charged particle trajectories (tracks). Recently, breakthroughs in ATLAS track reconstruction have revolutionized the inner tracking detector’s ability to identify LLP decays and invigorated the ATLAS LLP search program. In this seminar, I will highlight the recent advancements in displaced track reconstruction and present the latest search results for LLP decays in the ATLAS ID. Additionally, I will discuss prospects for expanding the LLP search program at the High Luminosity LHC through further innovation in track reconstruction, and explain why there is reason to be optimistic about the future of particle physics at the LHC.
Host: David Strom
Tuesday, October 22 12:00 – 1:00 pm **SPECIAL DAY & TIME**
Gravitational Footprints of Early Matter Domination
Speaker: Jessie Shelton (University of Illinois Urbana-Champaign)
Abstract: The cosmic evolution of our universe prior to Big Bang Nucleosynthesis is almost entirely unknown. One generic possibility, motivated by models for dark matter, baryogenesis and beyond, is an epoch of early matter domination, where a metastable species temporarily makes up the dominant component of the universe. I will discuss some well-motivated scenarios, their imprint on early structure formation, and the resulting gravitational imprints they leave, including novel contributions to the stochastic gravitational wave background.
Host: Pouya Asadi
Monday, November 4 4:00 – 5:00 pm
An Introduction to Dispersion-Managed Nonlinear Schrödinger Equations
Speaker: Jason Murphy (University of Oregon – Mathematics)
Abstract: This talk will serve as an introduction to nonlinear Schrödinger equations (NLS) from both a physical and mathematical perspective. I will begin by introducing the cubic NLS as it arises in the context of nonlinear optics. I will then describe how some applications of this model lead us to consider a class of modified equations known as dispersion-managed nonlinear Schrödinger equations, for which our mathematical understanding is rather limited (compared to the standard NLS). Finally, I will discuss some recent results on dispersion-managed NLS, as well as some open problems for this model (including the important question of the existence of solitons).
Host: Jayson Paulose
Tuesday, November 12 4:00 – 5:00 pm **SPECIAL DAY**
Time Domain Astronomy in the Era of Big Data
Speaker: Sebastian Gomez (Harvard University)
Abstract: Time domain astronomy, or the study of the dynamic universe on human timescales, stands at the forefront of a revolution fueled by the advent of large surveys. In the past decades we have experienced an unprecedented influx of observations that led to the discovery of exotic transients such as superluminous supernovae and tidal disruption events, and pair-instability supernova candidates. The upcoming deployment of next-generation survey telescopes, such as the Vera C. Rubin Observatory and the Nancy Grace Roman Space Telescope, will increase our transient detection capabilities by two orders of magnitude. Development of machine learning techniques will prove to be not only useful, but necessary, to deal with the deluge of data we will obtain from these observatories, promising deeper insights into known cosmic phenomena and the exciting prospect of discovering entirely new classes of transients.
Host: Yvette Cendes
Wednesday, November 13 4:00 – 5:00 pm **SPECIAL DAY**
Overcoming the challenges of quantum interference in Higgs physics with Neural Simulation-Based Inference
Speaker: Aishik Ghosh (UC Irvine)
Abstract: Non-linear effects such as from quantum interference pose significant challenges to the established statistical methods employed at the Large Hadron Collider (LHC). These are of particular concern in some of the most important measurements in collider physics, including that of the Higgs width. Neural Simulation-Based Inference is a powerful class of machine learning-based methods for statistical inference that naturally handle these challenges by performing high dimensional parameter estimation without the need to bin data into low-dimensional summary histograms. I will discuss these challenges in Higgs physics and the solution developed, first in a phenomenology study, and then implemented in the ATLAS experiment. The dramatic improvement in sensitivity for a flagship Higgs measurement promises significant gains to be had in several other studies at the LHC and more generally in particle physics with the use of this newly developed method.
Host: Ben Lillard
Monday, November 25 || No Seminar – Happy Thanksgiving!
Monday, December 2 4:00 – 5:00 pm
Title: Road to Minimal WIMPs
Speaker: Rodolfo Capdevilla (Fermilab)
Abstract: Minimal WIMP models extend the Standard Model with an electroweak multiplet whose neutral component $\chi_0$ serves as Dark Matter (DM). Direct Detection (DD) and Indirect Detection (ID) searches probe these models especially when $\chi_0$ accounts for 100% of DM (the thermal target). Colliders aim to produce the charged members of the multiplet, which produce interesting signals when they decay. These searches are more effective when $\chi_0$ accounts for a fraction of DM, as this leads to a lower mass multiplet and larger production cross sections. This shows an interesting complementarity between DD, ID, and colliders. In this talk, I discuss the role that present and future colliders can play in discovering Minimal WIMPs. I show how a 3 TeV muon collider can discover the elusive doublet (Higgsino-like) state up to its thermal target. As the collider energy increases, larger multiplets become accessible. A 10 TeV muon collider could discover the triplet (Wino-like) state up to its thermal target as well as a quintuplet state that accounts for ~10% of DM. These results indicate an interesting path ahead towards the possible discovery of the long standing minimal WIMPs.
Host: Pouya Asadi
Monday, December 9 4:00 – 5:00 pm
Title: Phenomenology of strongly interacting dark sectors with light vector mesons
Speaker: Elias Bernreuther (University of California, San Diego)
Abstract: Stable dark matter (DM) particles may arise as dark pions from the confinement of dark quarks in a strongly interacting dark sector. Their relic abundance is determined not by annihilations into visible particles but by dark pion number-changing processes within the dark sector. However, this so-called SIMP mechanism faces prohibitive constraints from bounds on DM self-interactions. In this talk I will show that annihilations involving dark vector mesons in the final state dominate over the traditionally studied SIMP process if the dark vector mesons are sufficiently light. As a result, the preferred DM mass scale increases and DM self-interaction bounds can be evaded. At the same time, this scenario predicts visible dark meson decays, which can give rise to striking new collider signatures. I will show in particular that Belle-II has excellent sensitivity to the resulting dark shower signals.
Host: Pouya Asadi