[Rgc_analysis] [EXTERNAL] Re: [Rgc] RGC-analysis meeting tomorrow

[Sebastian Kuhn]

So, to me it looks like that the worsening of the Mx resolution in exclusive rho production is NOT related to the difference between CCDB and sqlite - in fact, it looks like it got even a tiny little bit WORSE with Harut’s most recent plots (CCDB) - counter to the other (elastic and pDVCS) results. In any case, this should have no bearing on the review tomorrow - there are many things one can check to hopefully improve that resolution for Winter/Spring ’23 - including a careful accounting for the target position (which appears to be different), checking all cuts and background subtractions, etc. (BTW, I’m afraid we really need to check all vertex distributions for EVERY EPOCH, where an epoch refers to a set of runs during which no manipulations on the target occurred - including material changes, motion, repairs etc.)

This leaves us with the SLIGHT remaining difference between CCDB and sqlite for some of the elastic and DVCS distributions. We should triple-check that these are really labeled correctly, since it is surprising why a small IMPROVEMENT in vertex resolution (which is what Derek’s plots show) could result in a worse resolution in phi etc. In fact, here is a theorem: To first order, Delta-phi between the electron and the proton in a truly elastic event DOES NOT DEPEND ON THE VERTEX AT ALL!
Again, we may have to check cuts, analysis procedures etc. to understand this small difference, but the way we should present this to the committee is by saying that either version would be fine to use, and unless we are convinced that sqlite actually improves the resolution, we’ll stick with CCDB. (This should be clarified in the time frame that usually expires anyway between the presentation and the final response to all requests from the committee. It certainly should not require a repeat of the review nor hold up the green light for cooking).

- Sebastian

On Feb 18, 2025, at 11:29, harut avagyan via Rgc_analysis <rgc_analysis at jlab.org> wrote:

Hi Silvia,
I somehow managed to create some ntuples. I will continue checking their integrity, but what I got, doesn't support my hope that with the rcdb version the resolution of the rho missing mass peak will improve. The plots are in https://userweb.jlab.org/~avakian/tmp/rhocompele-inb.rcdb.pdf
They include now also all kinds of vertex (x,y,z) distributions for e-,\pi+ and pi- and they all seem to be shifted. One can check if they are consistent with what we expect.
BEst,
Harut

On Tue, Feb 18, 2025 at 10:50 AM harut avagyan <avagyan.harut at gmail.com<mailto:avagyan.harut at gmail.com>> wrote:
Dear All,
One strange thing, I guess also others observed, is the shift of the target center along z. That is confirmed by z-vertex comparison of the electrons in exclusive rho (see https://userweb.jlab.org/~avakian/tmp/RGC-e-vertex.pdf).  If  the  shift of ~2cm (inbending only compared)  is real, the loss of high energy electrons in inbending in old configuration compared to new one is hard to link to it.
Could target people confirm that possibility?
Thanks,
Harut

On Mon, Feb 17, 2025 at 4:33 PM silvia via Rgc <rgc at jlab.org<mailto:rgc at jlab.org>> wrote:
Dear all,
we'll have our RGC-analysis meeting tomorrow, Tuesday, at 8:30AM JLab
time, zoom link: https://jlab-org.zoomgov.com/j/1609368114<https://urldefense.proofpoint.com/v2/url?u=https-3A__jlab-2Dorg.zoomgov.com_j_1609368114&d=DwMFaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=aSEBncnFTdfouxOejKajYG--Ygz0DFQolIcHUhF20pw&m=eOQtJErmkjqJOoGl4Dsu4IQFuYKWAm3aaZQasTu6pVRmyK1eRx_i5n3I3W-2pnm9&s=yo7hTiwe_hi5tOGeI4yW60EGUfyXFTAl-zIKVbDedfQ&e=> , wiki page:
https://clasweb.jlab.org/wiki/index.php/RGC_Feb18
Please let me know if you plan to present something.
Best regards,
Silvia
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