[Theory-seminars] Theory Seminar Monday

[Joseph Karpie]

Hey everyone,

Because of JLab's cancellation due to the inclement weather, we will be rescheduling this week's seminar for Wednesday at 1pm in F224-225.
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From: Joseph Karpie
Sent: Friday, January 23, 2026 5:43 PM
To: Adam Freese via Theory-seminars <theory-seminars at jlab.org>
Subject: Theory Seminar Monday

Hey everyone,

Please join us Monday at 1pm in L102 for a seminar by Wei-Yang Liu (UConn).

Title: Hadronic Structure Emerged from Topological Vacuum — Buried treasure in the sand of the QCD sea

Abstract:

We develop an effective theory based on the low resolution structure of the QCD vacuum aligned with the gradient flow renormalization scheme where the QCD ensemble is modeled as a dilute liquid of instantons and anti-instantons with sea quarks hopping around those topological gauge field configurations. With this picture, we construct a systematic density expansion with diagrammatic Feynman rules to nonperturbatively evaluate vacuum correlation functions, and hadron matrix elements (form factors) of light hadrons. As a proof of principle, we compute the gluonic scalar, gravitational form factors, and C-odd three gluon operators to reveal the gluonic structure of hadrons. We also further apply the resulting form factors to analyze the gluon dominance in quarkonium photo-production near the threshold. The results are in good agreement with current experiments and recent lattice QCD results, demonstrating that semiclassical vacuum theory provides a robust nonperturbative framework for quantitative predictions with clear physical interpretation for hadron structure.



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Joe Karpie
Pronouns: He/His/Him
Postdoctoral Fellow
Theoretical and Computational Physics Center
Jefferson Lab

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