[Clas12_rgb] concerning figure 5 of nDVCS paper draft, VGG predictions compared with our data
ajhobart
ajhobart at jlab.org
Wed Jun 5 11:21:57 EDT 2024
I introduced three more curves correspondig to resonable reduced
chi2values and positive Ju (attached plot)
// ju jd reduced chi2
//-0.45 0.2 3.03423 blue
//-0.25 0.15 3.19268 black
//-0.2 0.15 3.1004 Red
// 0.05 0.1 3.4503 reddishlike
// 0.1 0.1 3.39791 green
// 0.35 0.05 3.77249 gray
in particular, and following FX comment, the gray curve corresponding to
Ju = 0.35 and Jd=0.05 seems to be the closest (but still far, compatible
within statistics) to what Lattice QCD evaluations suggest.
We do not intend to show plots of reduced chi2, this plot was intended
for internal use, only figure 5 (attached her) is intended for publication.
Valery, here I put a 2D profile with Ju vs Jd and color code
corresponding to chi2 value for the chi<10
and for chi2<minimu chi2 +1
the last plot shows that there is no preferred value for Ju, as
explained before and that Jd is probably around 0.1 - 0.15
let me know what you think
thanks a lot
Cheers
Adam
Le 05/06/2024 à 16:13, Francois-Xavier Girod a écrit :
> Dear all
>
> I assume this is intended to go in the collaboration paper
> These 2D plots are very hard to read. It's good for intermediary steps
> in the internal process, when people look very carefully at the plots
> and think about them for a long time. But for publication in my
> opinion it would be better to show a pair of 1D plots, one with fixed
> Ju showing chi2 vs Jd, and one with fixed Jd showing chi2 vs Ju
>
> There are some lattice calculations for these quantities, we should be
> careful if we are going to publish results suggesting the
> collaboration results disagree with lattice estimations
>
> Best regards
> FX
>
> On Wed, Jun 5, 2024 at 9:57 AM ajhobart via Clas12_rgb
> <clas12_rgb at jlab.org> wrote:
>
> the number of fits having the particular chi2, sorry I have
> omitted it from the previous screenshot, here it is
>
> Thanks
>
> Adam
>
> Le 05/06/2024 à 15:53, Sebastian Kuhn a écrit :
>> Thanks for the explanation. Can you tell me what information is
>> coded in the color of each block?
>>
>>> On Jun 5, 2024, at 9:39 AM, ajhobart <ajhobart at jlab.org>
>>> <mailto:ajhobart at jlab.org> wrote:
>>>
>>> Hi Sebastian,
>>>
>>> For figure 5, the limit on the reduced chi2 that I put affects
>>> the set of accepted sets of Ju and Jd. The Limit is now 3.5, if
>>> I move it ot 5 I have a set of accepted sets of Ju and Jd that
>>> contains positive values of Ju (50% of selected fits). So maybe
>>> it is our choice that gave the impression that only negative Ju
>>> values are reasonable!
>>>
>>> My reasoning is that there are preferred values for Jd (positive
>>> around 0.15) but no preferred values for Ju, I attach here again
>>> the same plot showing Ju vs Jd versus chi2 from a different
>>> angle. It shows that on the Ju axes, the distribution for chi2
>>> is almost Flat.<gsudaQzbHjfz8PDK.png>
>>>
>>> However, my take on this is that rather none of the combinations
>>> of Ju and Jd reproduces the data correctly. Even for the ones we
>>> chose to put in the figure 5, it is quite clear that the trend
>>> seen in the data is not consistant with the curves. Moreover,
>>> VGG predictions remain model dependant predictions and we do not
>>> intend to consider them as a strong physics conclusions on the
>>> values of Ju and Jd.
>>>
>>> thanks
>>>
>>> Best regards
>>>
>>> Adam
>>>
>>> Le 05/06/2024 à 14:38, Sebastian Kuhn a écrit :
>>>> Just a quick question: Why are all the preferred values for J_u negative and for J_d positive? This seems very counter-intuitive, given that the quark helicity contributions to J have the exact opposite sign. This would require enormous (overcompensating) orbital angular momenta to explain.
>>>>
>>>> - Sebastian
>>>>
>>>>> On Jun 5, 2024, at 4:07 AM, ajhobart via Clas12_rgb<clas12_rgb at jlab.org> <mailto:clas12_rgb at jlab.org> wrote:
>>>>>
>>>>> Dear Valery, RGB,
>>>>>
>>>>> following our discussion during the last RGB meeting concerning figure 5 of the nDVCS paper draft, we have performed a scan using VGG of different values of Ju and Jd and evaluating for each set a chi2 with the 9 data points that we extract with our analysis. Indeed, this scan has shown that there are other values of Ju and Jd that are more "preferred" by our extracted harmonics than the ones we had initially put in the paper. We have updated figure 5 accordingly (I attach it here also).
>>>>>
>>>>> color code for figure 5
>>>>>
>>>>> // ju jd reduced chi2
>>>>> //-0.45 0.2 3.03423 blue
>>>>> //-0.25 0.15 3.19268 black
>>>>> //-0.2 0.15 3.1004 Red
>>>>>
>>>>> Attached also you will find the plot with Ju, Jd and chi2 value for each set as you requested. It seems that there is a particular preferred range for Jd (around 0.15) but none for Ju.
>>>>>
>>>>>
>>>>> thanks
>>>>>
>>>>> Best regards
>>>>>
>>>>> Adam
>>>>> <bsa_q2xbjt_coloronline_newVGG.pdf><jujdchi2.png>_______________________________________________
>>>>> Clas12_rgb mailing list
>>>>> Clas12_rgb at jlab.org
>>>>> https://mailman.jlab.org/mailman/listinfo/clas12_rgb
>>
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