[Theory-seminars] Theory Seminar Monday (remote) - Bigeng Wang

[Zheng-Yang Li]

Dear all,

On Monday, January 29th, 2024 at 1pm EST, we will have a virtual seminar given by Bigeng Wang of U Kentucky on the Zoom for Government link:

https://jlab-org.zoomgov.com/j/1603207306?pwd=YUxnN0VXSG1SWjIvZ1czZkp0dm9xQT09

Please see below for the title and abstract.


Theory Seminar: January 29th, 1pm EST (virtual)


Speaker: Bigeng Wang (U Kentucky)


Title: Trace anomaly form factor from lattice QCD


Abstract: The hadron mass can be obtained through the calculation of the trace of the energy momentum tensor (EMT) in the hadron which includes the trace anomaly and sigma terms. The anomaly due to the conformal symmetry breaking is believed to be an important ingredient for hadron mass generation and confinement. In this talk, I will present the calculation of the glue part of the trace anomaly form factors of the pion up to $Q^2\sim 4.3~\mathrm{GeV}^2$ and the nucleon up to $Q^2\sim 1~\mathrm{GeV}^2$. The calculations are performed on a domain wall fermion (DWF) ensemble with overlap valence quarks at 7 valence pion masses varying from $\sim 250$ MeV to $\sim 540$ MeV, including the unitary point $\sim 340$ MeV. We calculate the radius of the glue trace anomaly for the pion and the nucleon from the $z$-expansion. By performing a two-dimensional Fourier transform on the glue trace anomaly form factors in the infinite momentum frame with no energy transfer, we also obtain their spatial distributions for several valence quark masses. The results are extrapolated to the physical pion mass. We find the pion's form factor changes sign, as does its spatial distribution, for light quark masses. This explains how the trace anomaly contribution to the pion mass approaches zero toward the chiral limit.


See you on Monday.


Best regards,

Caroline, Joe, and Zheng-Yang


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