[Theory-seminars] Cake Seminar Monday - Sungwoo Park

[Colin Egerer]

Hello All,

This coming Monday, November 1st at 1:00PM (EDT), our very own Sungwoo Park will give a cake seminar on https://jlab.bluejeans.com/319089525/6769<https://urldefense.proofpoint.com/v2/url?u=https-3A__jlab.bluejeans.com_319089525_6769&d=DwMFAw&c=CJqEzB1piLOyyvZjb8YUQw&r=AIMSQQ81YDyrZuJNGks2qw&m=x29E57UMx34WjoS-yLXZS2qNLfa_SlSw0J1QuFd6u80&s=YZDnEovFtz29HvbN26a0A0rgHtJ1M_tEUQ7YAbyNdgA&e=>.
Please see below for the details. And as we cannot join in person for cake, feel free to bring your favorite variety along.

Cake Seminar
Monday November 1st, 1:00PM

Sungwoo Park (JLab) will speak about "The pion–nucleon sigma term from lattice QCD"

Abstract:
In this talk, we present a lattice QCD analysis of the pion--nucleon sigma-term. One of the most serious systematic effect in lattice calculations of nucleon correlation functions is the contribution of excited states. We estimate these using chiral perturbation theory (ChPT), and show that the leading contribution to the isoscalar scalar charge comes from $N\pi$ and $N\pi\pi$ states. Therefore, we carry out two analyses of lattice data to remove excited-state contamination, the standard one and a new one including $N\pi$ and $N\pi\pi$ states. We find that the standard analysis gives the sigma-term of 41.9(4.9) MeV, consistent with previous lattice calculations, while our preferred ChPT-motivated analysis gives 59.6(7.4) MeV, which is consistent with phenomenological values obtained using pion--nucleon scattering data. Our data on one physical pion mass ensemble was crucial for exposing this difference, therefore, calculations on additional physical mass ensembles are needed to confirm our result and resolve the tension between lattice QCD and phenomenology.

Reference: 2105.12095


Have a pleasant weekend!
Astrid, Colin, and Patrick
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