Speaker: Vazha Loladze
Title: Dynamics of the Fermion-Rotor System
Room: 3024
Host: Markus Luty
Abstract: In this talk, I will examine the dynamics of the fermion–rotor system, originally introduced by Polchinski as a toy model for monopole–fermion scattering. Despite its simplicity, the system is surprisingly subtle, with ingoing and outgoing fermion fields carrying different quantum numbers. I will show that the rotor acts as a twist operator in the low-energy theory, changing the quantum numbers of excitations that have previously passed through the origin to ensure scattering consistent with all symmetries, thereby resolving the long-standing Unitarity puzzle. I will then discuss generalizations of this setup with multiple rotors and unequal charges, and demonstrate how the system can be viewed as a UV-completion of boundary states for chiral theories, establishing a connection to the resolution of the puzzle using boundary conformal field theory.
User:
High-Energy Seminars
Time:
4:00pm - 5:00pm
Location:
PHY 285
Send Reminder:
Yes - 20251126
Description:
Speaker: Jens Osterhoff (LBL)
Title: Wakefield Accelerator Colliders for Particle Physics
Room: 285
Host: Matthew Citron
Abstract: Since its inception, the field of advanced accelerator research has regarded future particle-physics colliders as the ultimate application of >1 GV/m accelerator technology. Over the last decades, great experimental and theoretical progress [1,2,3] has enabled and motivated new concepts for potential future colliders based on wakefield accelerators (WFAs), both for Higgs factories and at the energy frontier. The most recent P5 Report [4] calls for “vigorous R&D toward a cost-effective 10 TeV pCM collider based on proton, muon, or possible wakefield technologies.” Specifically, the P5 Report requests “the delivery of an end-to-end design concept, including cost scales, with self-consistent parameters throughout” for a WFA machine. This presentation will outline the plan to produce such a design, and the opportunities and challenges for wakefield-based colliders, both as standalone machines and as a future technology upgrade option. WFA colliders at the energy frontier will likely operate in a new regime characterized by beam-beam interactions with large quantum beamstrahlung effects. Preliminary studies of the physics case in this regime at 10 TeV will be presented.
[1] C. A. Lindstrøm et al. “Beam-driven plasma-wakefield acceleration”, arXiv:2504.05558 (2025)
[2] E. Esarey et al. “Physics of laser-driven plasma-based electron accelerators”, Rev. Mod. Phys. 81, 1229 (2009)
[3] C. Jing “Dielectric Wakefield Accelerators”, Rev. Accel. Sci. Tech, 9, 127 (2016)
[4] P5 Report www.usparticlephysics.org/2023-p5-report/
