[Clas12_dileptons] Meeting tomorrow

[Pawel Nadel-Turonski]

Hi Richard,

Sorry, I should have explained more clearly. The HERA results are a little older and were not discussed directly at DIS. Cedric gave a slightly confusing talk about the gluon radius, though.

But what HERA did measure the t-slope in J/psi production. And I talked to Bjoern Schenke who is one of theorists working on the “hot spot” picture of the proton. In their latest paper,

https://arxiv.org/pdf/2202.01998.pdf

they discuss the impact of the HERA data on the proton radius. And with three hot spots, this is 0.61+0.065-0.068 fm, which is generally compatible with our data. Any discrepancy can be attributed to how the hot spots are seeded.

Now, this is not the only high-energy model of the proton, but it is very encouraging that different pictures converge on a similar conclusion. One could, of course, also look directly at the original HERA publications.

Ultimately, this will hopefully be resolved by measuring the gluon GPD over a wide range in x at the EIC. But the combination of JLab and HERA results seems very interesting!

Best,

Pawel



On Apr 19, 2024, at 1:05 PM, Richard Tyson <tyson at jlab.org<mailto:tyson at jlab.org>> wrote:

Hi Pawel,

Thank you for pointing this out. Could you send the link to the talk/publication that discussed the HERA estimate of the gluonic radius? I couldn't find it from looking at the DIS timetable.

Thanks,
Richard
________________________________
From: Clas12_dileptons <clas12_dileptons-bounces at jlab.org<mailto:clas12_dileptons-bounces at jlab.org>> on behalf of Pawel Nadel-Turonski via Clas12_dileptons <clas12_dileptons at jlab.org<mailto:clas12_dileptons at jlab.org>>
Sent: Thursday, April 18, 2024 5:19 PM
To: Rafayel Paremuzyan <rafopar at jlab.org<mailto:rafopar at jlab.org>>
Cc: Clas12_dileptons at jlab.org<mailto:Clas12_dileptons at jlab.org> <clas12_dileptons at jlab.org<mailto:clas12_dileptons at jlab.org>>
Subject: Re: [Clas12_dileptons] Meeting tomorrow

Hello Everyone,

I was at DIS in Grenoble last week and am still catching up a little, but I just wanted to mention on thing regarding the J/psi, which could be relevant for the RGA jeopardy.

Comparing with other JLab results is, of course, important - but perhaps even more so is that there are data on J/psi production from HERA that also indicate that the gluonic radius is smaller than the quark one. And since these were taken at higher energy where theory is more robust, it could be worth mentioning.

Best,

Pawel


On Apr 15, 2024, at 4:39 PM, Rafayel Paremuzyan via Clas12_dileptons <clas12_dileptons at jlab.org<mailto:clas12_dileptons at jlab.org>> wrote:

Dear all,

We will have the a meeting tomorrow at 08:30 EST.

Please put your slides into the meeting page
https://clasweb.jlab.org/rungroups/tlc/wiki/index.php/Meet_April_16_24

The meeting room at JLab is F228

https://jlab-org.zoomgov.com/j/1617534470?pwd=UkR3RlZOSVk3V1RQY2JnMUdIM3RMUT09
Join our Cloud HD Video Meeting<https://jlab-org.zoomgov.com/j/1617534470?pwd=UkR3RlZOSVk3V1RQY2JnMUdIM3RMUT09>
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Rafo
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