General Meson SF Meeting Summary 4/20/23

PARTICIPANTS: Garth Huber, Tanja Horn, David Richards, Adnan Bashir, Jorge Segovia, Love Preet, Patrick Barry, Richard Trotta, Rolf Ent, Stephen Kay, Tobias Frederico, Tyler Hague

EXPERIMENT PRESENTATION

• Meson Form factors - detailed acceptance and reconstruction resolution studies with appropriate weights (Garth, Love)

• timescale ~ 1 year

• Meson Structure functions (Richard, Rachel)

LATTICE

• Meson TMDs - LQCD (David)

• no light cone so cannot compute TMDs directly on the lattice, but can compute matrix elements that can be related to PDF or TMDs
• when compute matrix elements then compute matrix elements of quark and anti quark separated by some distance - in the Short Distance factorization (Large Momentum Effective Theory - LaMET) one can relate this to TMDs

• Pion PDF has been calculated in this short distance factorization approach - emphasis on rigorous implementation, e.g., in the LaMET approach, and determination of normalization (Collins-Soper Kernel)

• HadStruc (JLab): current emphasis in hadron structure is on GPDs within short0distance factorization, but method is extendable to TMDs

• Pion: calculation of the x-dependent PionDA (D. Kovner, GHP) - next paper on this

• Time scale

• Pion DA paper should be out in about 3 months
• within ~ 1 year should have high precision PDF and so foundation for TMDs

3D STRUCTURE OF MESONS

• Global analysis through fixed target DY data for direct comparison of pion and kaon transverse-spatial correlations

• find that pion spatial distribution more narrow than that of the proton
• pion average bT is smaller than that of proton in the range of the data, interpretation pion smaller object and so tighter, this also observed in transverse space; at large x, transverse size increases for both

• How would such correlations look like for J/Psi, a pointlike particle

COMPARE TO LAST PAPER

• Focus on more difficult things like Kaon FF and - more speculative measurements and calculations on mesons

THEORY

• Quark unpolarized transverse-momentum distribution functions of the pion (Tobias)

• T-even TMS leading twist from the quark correlations

• Working on includion of quark self energy

• Pion/kaon and other pseudoscalar mesons based on Schwinger-Dyson

• calculated GPD for pion and kaon and PDF and FF (Adnan)
• applied to TMDs (Jorge)

NEXT MEETING: 11 MAY AT 9AM ET