[Theory-seminars] Theory Seminar Tomorrow - Martha Constantinou

[Caroline Costa]

Hello All,

Tomorrow, February 7th at 1:00PM (EST), Martha Constantinou will give a (virtual) theory seminar on: https://jlab-org.zoomgov.com/j/1611179843?pwd=M09CNTFpbFVZSW1IQlhIMGp3RUVHUT09
Please see below for the title and abstract of Martha's talk.

Theory Seminar
Monday, February 7th at 1:00PM

Martha Constantinou (Temple University)
will speak about "Pion and kaon structure from Mellin moments of PDFs and GPDs"

Abstract:

Pions and kaons play an important role in understanding QCD dynamics, and the interplay between the emergent hadronic mass and the Higgs mechanisms. Kaons are particularly interesting because of the valence strange quark, which has a larger mass than the up and down quarks that form the pions. Due to the presence of a valence strange quark in the kaon, a comparison between pion and kaon observables provides a unique window into SU(3) flavor breaking effects. Such effects have already been observed in the pion and kaon.



While the proton has been extensively studied in lattice QCD, there are limited studies on the pion and kaon structure. Given the relatively small number of experimental data, it is crucial to obtain results from first principles. In this talk, we present a direct lattice QCD calculation of the first three non-trivial Mellin moments of PDFs for the pion and kaon. We also present results for the scalar, vector and tensor form factors. We use one ensemble of Nf=2+1+1 gauge configurations of maximally twisted mass fermions improved with a clover term. The ensemble corresponds to a pion mass of about 260 MeV and a kaon mass of about 530 MeV. We study excited-states contamination in detail using several values of the source-sink time separation within the range of 1.12 - 2.23fm. We use operators that are free of mixing and apply a multiplicative renormalization function calculated non-perturbatively.



One important aspect of our analysis is the reconstruction of the x-dependence of the pion and kaon PDFs using the Mellin moments calculated in this work. We find that the reconstruction is feasible, and we draw qualitative conclusions on the large-x behavior. The PDF reconstruction also allows the extraction of higher moments with reasonable statistical errors. A highlight of the calculation on the form factors is the extraction of the lowest moment of the densities of transversely polarized quarks in the impact parameter space.


See you tomorrow!
Caroline, Colin & Patrick

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