[Hadstruct] Minutes of 2/5 meeting...

[David Richards]

Dear all,

The minutes are below.  Note that I have updated proposals and presentations to our wiki https://github.com/JeffersonLab/HadStruc/wiki. To access that, you need both to be a member of the JLab “people", and me a member of the HadStruc “team".

Regards,
David



Present: CE,CC,TK,ER,RS,WM,DR,KO,AR,JK,RE

• Colin gave a presentation on the pseudo-ITD of the nucleon computed using distillation, using a single interpolating operator, on the same ensemble as that used for the dynamical pseudo-distribution paper. The computation was performed for two momenta, up to separations z=8, without DGLAP evolution. The data appeared notably more precise than the previous, FH way of calculating the matrix element. The matrix element was summed over all points between source and sink, and it was suggested that the sum should instead avoid the end points of the range. JK noted that the previous calculation included the operator inserted at all points on the lattice, including those for the incorrect time ordering, that might increase the contribution of excited states. The next stage would be to implement phase smearing to get to higher momentum and hence Ioffe time.

• There was considerable discussion of computer usage. KO noted that with the success of the calculation CE presented, we should put our effort into building a library of "generalized perambulators" to use up the computer time, and then perform the analysis in due course. To do so would require multiple users to exploit the system, so RS, TK and CE would run the 32^3 lattices at Frontera.

• The need to move to larger, 48^3 lattices was discussed, both to investigate finite volume effects, and to provide a finer resolution in Ioffe time. ER and DR would look at this, with the aim of using more Eigenvectors, say 96, than the 64 used in the current analysis.

• JLab computer time was being used for single current insertions, relevant to the EW form factors.

• A range of physics quantities could be computed using the current methodology: PDFs of both pion and nucleon, pion quark-distribution amplitudes. CE noted that he had began looking at kaon PDFs using the LCS approach. A further task, that formed the core of the ALCC proposal, was the off-forward matrix elements in GPDs; RE noted there was still some outstanding work needed there.

Next Meeting

12th Feb at 9:30am
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