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<div class="elementToProof"><span style="font-size:12pt;margin:0px">Dear Axel,</span></div>
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<div style="font-size:12pt;margin:0px">A non-TPE topic that can be pursued with a positron beam is the electromagnetic polarizabilities of the proton.</div>
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<div style="font-size:12pt;margin:0px">Our most recent results from Hall-C point to an anomaly in the electric generalized polarizability of the proton. The paper was accepted in Nature three weeks ago, but it is not published yet. The use of positron beams
will enable an alternative experimental path to extend further this program and to conduct an independent cross check of the effect. The latter, as we all know, is extremely valuable in cases like that.</div>
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<div style="font-size:12pt;margin:0px">Feel free to refer to it in your talk, if you want to discuss "other relevant avenues".</div>
<div style="font-size:12pt;margin:0px" class="elementToProof">This of course could in principle fit also nicely in Carlos' talk, since the electric GP (being the electric "strechability" of the proton) can be discussed in the context of the 3D structure of
hadrons. </div>
<div style="font-size:12pt;margin:0px">If you, Carlos or Thia want input or a slide for your talks, please let me know and I can prepare and send something.</div>
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<div style="font-size:12pt;margin:0px">Cheers,</div>
<span style="font-size:12pt;margin:0px">Nikos</span>
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<div class="PlainText elementToProof">---------------------------- Original Message ----------------------------<br>
Subject: [Pwg] [EXTERNAL] Positrons and TPE at QCD Town Hall<br>
From: "Axel Schmidt" <axelschmidt@gwu.edu><br>
Date: Thu, September 15, 2022 10:45 am<br>
To: pwg@jlab.org<br>
Cc: voutier@ipno.in2p3.fr<br>
--------------------------------------------------------------------------<br>
<br>
Dear Positron Working Group Colleagues,<br>
I was invited by the organizers of the Hot and Cold QCD Town Hall to talk<br>
for 15+5 on "Two-Photon Exchange Measurements." The organizers went on to<br>
request that "This talk should emphasize the JLab positron beam program,<br>
and can, of course, extend to other relevant avenues as you see fit ..."<br>
<br>
I see two other talks that will mention the JLab Positron Program:<br>
- Carlos Munoz Camacho: "3D Structure of Hadrons probed with Electrons<br>
and Positrons"<br>
- Thia Keppel: "JLab Upgrade Perspectives"<br>
<br>
While I have not coordinated with any of the other speakers yet, I do not<br>
see any other talks at the Town Hall representing the other excellent<br>
physics cases for positrons (SIDIS, Dark Matter, etc.).<br>
<br>
As I gather materials and prepare my talk, I would be really grateful for<br>
your input. I am curious to hear, In your view,<br>
- What message should be emphasized?<br>
- Are there any topics / claims / statements that I should absolutely<br>
avoid (so-called "third rails.")?<br>
- If you have a slide or two that you'd like me to share, perhaps on<br>
non-two-photon topics, I'd be glad to borrow from it.<br>
<br>
I really want to portray our working group in the best possible light!<br>
<br>
Thanks for your help,<br>
-Axel<br>
<br>
<br>
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