Joint Theory Seminar
Speaker: Gilly Elor (U. Oregon)
Title: Soft-Collinear Supersymmetry
Host: Xiaochuan Lu
Room: 432
Abstract: Soft-Collinear Effective Theory (SCET) is a framework for modeling the infrared structure of theories whose long distance behavior is dominated by soft and collinear divergences. I will demonstrate that SCET can be made compatible with supersymmetry (SUSY), explicitly with N = 1 SUSY Yang-Mills. For contrast arguments will be given that chiral SUSY theories with Yukawa couplings, specifically the single flavor Wess-Zumino model, are incompatible with the collinear expansion. SCET is formulated by expanding fields along a light-like direction and then subsequently integrating out degrees-of-freedom that are away from the light cone. Defining the theory with respect to a specific frame obscures Lorentz invariance - given that SUSY is a space-time symmetry, this presents a possible obstruction. The cleanest language with which to expose the congruence between SUSY and SCET requires exploring two novel formalisms which I will discuss: collinear fermions as two-component Weyl spinors, and SCET in light-cone gauge. By expressing SUSY Yang-Mills in "collinear superspace", a slice of superspace derived by integrating out half the fermionic coordinates, the light-cone gauge SUSY SCET theory can be written in terms of superfields. As a byproduct bootstrapping up to the full theory yields the first algorithmic approach for determining the SUSY Yang-Mills on-shell superspace action. This work paves the way towards discovering the effective theory for the collinear limit of N=4 SUSY Yang-Mills.
User:
High-Energy Seminars
Time:
9:10am - 10:10am
Send Reminder:
Yes - 1 day 4 hour 0 minutes before start
Description:
High Energy Seminar
Speaker:
Title:
Host:
Room: 285
Abstract:
User:
High-Energy Seminars
Time:
6:30am - 7:30am
Send Reminder:
Yes - 3 days 4 hour 0 minutes before start
Description:
Joint Theory Seminar
Speaker:
Title:
Host:
Room: 432
Abstract:
User:
High-Energy Seminars
Time:
9:10am - 10:10am
Send Reminder:
Yes - 1 day 4 hour 0 minutes before start
Description:
High Energy Seminar
Speaker:
Title:
Host:
Room: 285
Abstract:
User:
High-Energy Seminars
Time:
6:30am - 7:30am
Send Reminder:
Yes - 3 days 4 hour 0 minutes before start
Description:
Joint Theory Seminar
Speaker: Kohsaku Tobioka (Weizmann & KEK & Tel Aviv U.)
Title: Particle Production for Inflation and Relaxion
Host: Xiaochuan Lu
Room: 432
Abstract: Under time-dependent background, some particles can become light and those particles are produced (in non-perturbative way). Such particle production takes important roles in the early universe because the background is changing during inflation and preheating. Also, the relaxion mechanism, a dynamical approach to fine-tuning problem, has a condition that particle production happens. In this talk, I discuss particle production of scalars and gauge bosons for relaxion and inflation. In particular, we investigate aspects of possible replacement of relaxion wiggle, new dissipative force of inflation, and reheating of relaxion.
User:
High-Energy Seminars
Time:
9:10am - 10:10am
Send Reminder:
Yes - 1 day 4 hour 0 minutes before start
Description:
High Energy Seminar
Speaker: Eric Prebys
Title: The Fermilab Accelerator Science and Technology (FAST) Facility
Host:
Room: 285
Abstract:
The Fermilab Accelerator Science and Technology (FAST) facility is a dedicated accelerator physics R&D project at Fermilab. The centerpiece of the facility is the Integrable Optics Test Accelerator (IOTA) which is being built to investigate stable particle optics incorporating nonlinear magnetic fields. If successful, such optics could enable the storage and acceleration of more intense beams than are possible with traditional linear optics. This would greatly aid the lab in achieving the beam intensity required by its long term physics goals, as well as being of general use in the field. The IOTA ring will initially be tested with a 150 electron beam, which incorporates a prototype ILC front end and cryomodule. In addition to supporting IOTA ring, this electron beam facilites a diverse R&D program of its own. This seminar will present the motivation for FAST, current status, and long term plans, including the introduction
of proton injection into IOTA.
User:
High-Energy Seminars
Time:
6:30am - 7:30am
Send Reminder:
Yes - 3 days 4 hour 0 minutes before start
Description:
Joint Theory Seminar
Speaker: John Kearney (Fermilab)
Title: A (The?) Higgs Vacuum Instability During Inflation
Host: Xiaochuan Lu
Room: 432
Abstract: Supposing there exists no new physics stabilizing the weak scale, the Standard Model Higgs potential exhibits a true vacuum at large field values, rendering the electroweak vacuum metastable (i.e., long lived relative to the age of the Universe). While this scenario need not preclude our current existence, it may not reconcile with a period of large(ish)-field inflation---large fluctuations in the Higgs field, induced by the inflationary energy density, can lead to the field locally sampling the unstable/true vacuum part of the potential, with potentially disastrous consequences. Evaluating the extent to which large-field inflation and the Higgs vacuum instability are incompatible requires understanding (i) how Higgs fluctuations evolve during inflation and (ii) the fate of large local fluctuations that sample the part of the potential beyond the barrier that separates the electroweak and true vacua. In this talk, I will discuss both of these aspects, and explain the implications for large-field inflation.
User:
High-Energy Seminars
Time:
9:10am - 10:10am
Send Reminder:
Yes - 1 day 4 hour 0 minutes before start
Description:
High Energy Seminar
Speaker: Walter Hopkins
Title: Direct Stop Searches at ATLAS
Host:
Room: 285
Abstract:
Supersymmetry (SUSY) is an extension of the Standard Model that can resolve the gauge hierarchy problem. The SUSY partner to the top quark(stop) plays an important role in canceling the dominant top quark loop diagram contributions to the divergence of the Higgs boson mass. The recent increase of center-of-mass energy of the LHC from 8 TeV to 13 TeV greatly extends the mass reach for SUSY searches. A summary of the searches for direct stop production, highlighting the zero-lepton channel analysis using 13.3 $fb^{-1}$ of $\sqrt{s}=13$ TeV data collected with the ATLAS experiment at the LHC. One of the stop decay modes considered is the decay to a top and a neutral lightest supersymmetric particle (LSP) resulting in signature with jets and large missing energy. No significant excess is observed above the background expectation in the stop signal regions and limits are set on the stop and LSP masses. Additional signal regions are designed and interpreted for DM+ttbar production. Finally, the outlook for stop searches for the remainder of Run 2 will be discussed.
Description:
Halloween
User:
High-Energy Seminars
Time:
6:30am - 7:30am
Send Reminder:
Yes - 3 days 4 hour 0 minutes before start
Description:
Joint Theory Seminar
Speaker:Chris Verhaaren (UC Davis)
Title:Screening the Standard Model from Gravitation Lorentz Violation
Host: Verhaaren
Room: 432
Abstract:Lorentz symmetry may not be a fundamental symmetry of nature, but emergent at low energies. Experimental bounds in the matter sector are very constraining, but much less so in gravity. We show how strong dynamics can screen the Standard Model from gravitational Lorentz Violation. We estimate the size of these effects through the AdS/CFT correspondence, and demonstrate that the AdS predictions confirm our strong coupling intuition. In this framework, once the gravitational constraints are satisfied the matter sector is effectively unconstrained, setting the stage for exploring Lorentz Violating extensions of the Standard Model.
