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Hi Elton,</div>
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I can just comment that the 200 nb value I got has already a factor of 1.25 taken into account.</div>
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I also do not quite understand (maybe because it's 6 am already) why in Fig. 3 the units</div>
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are nb, not nb/GeV, maybe it is nb per histogram bin size, which is 50MeV I assume, or something else. Having Fig. 3 understood is essential for the cross-section results comparison,</div>
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because I used values from Jose and can/should put Fig. 3 values instead to compare the results directly.</div>
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Thank you,</div>
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Ilya</div>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>От:</b> Elton Smith <elton@jlab.org><br>
<b>Отправлено:</b> 28 февраля 2020 г. 15:15<br>
<b>Кому:</b> Elton Smith <elton@jlab.org><br>
<b>Копия:</b> Halld-npp@jlab.org <Halld-npp@jlab.org>; Ilya Larin <ilarin@jlab.org><br>
<b>Тема:</b> Primakoff cross section</font>
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<div class="PlainText">Hi Ilya,<br>
<br>
I compared your calculation of the cross section in the LOI. See figs. <br>
3-5. I get a cross section/nucleus of 345 nb. If you took Jose's cross <br>
section directly, you need to divide your value 200 nb by 0.8 since it <br>
is for |costhe|<0.8, which gives 250 nb, or 70% of my value.<br>
<br>
You can check my parameterization of sigma(gg->pi0pi0) (Fig. 3) with <br>
Jose's. I assumed it is essentially flat above the threshold instead of <br>
having a shape. This may explain most of the remaining discrepancy. We <br>
may wish to update the document with your value since Jose's <br>
parameterization is more constrained, but we can discuss this.<br>
<br>
Cheers, Elton.<br>
<br>
Elton Smith<br>
Jefferson Lab MS 12H3<br>
12000 Jefferson Ave STE 4<br>
Newport News, VA 23606<br>
(757)269-7625<br>
(757)269-6331 fax<br>
<br>
On 2/28/20 2:36 PM, Elton Smith wrote:<br>
> Dear collaborators,<br>
><br>
> I have posted the minutes from the NPP meeting this morning on the <br>
> wiki at <br>
> <a href="https://halldweb.jlab.org/wiki/index.php/Pi0_Polarizability_Meeting_Feb_28,_2020#Minutes">
https://halldweb.jlab.org/wiki/index.php/Pi0_Polarizability_Meeting_Feb_28,_2020#Minutes</a>.
<br>
><br>
><br>
> Ilya: You can go ahead an link your presentation directly to the <br>
> meeting page.<br>
><br>
> Thanks, Elton.<br>
><br>
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