[Clas12_verystrange] PAC comments

[Lei Guo]

I think most of the questions are very reasonable. But it seems that  
we HAVE to have a reasonable plot for the double moments.

Lei

Begin forwarded message:

> From: Diego Bettoni <bettoni at fe.infn.it>
> Date: June 12, 2012 8:26:25 AM EDT
> To: <lei.guo1 at fiu.edu>
> Cc: Reinhard Beck <beck at hiskp.uni-bonn.de>, "Naomi C.R. Makins" <makins at uiuc.edu 
> >
> Subject: PR12-12-008
>
> Dear Guo,
>  I am one of the readers of the proposal PR12-12-008 to be discussed  
> at PAC39 and I have a few comments questions at this time. Here they  
> are, in no particular order.
>
> 1. The Theory TAC raised some serious questions about the way the  
> proposal is written and also about the contents. Please make sure  
> that all these questions are addressed before the PAC presentation  
> next tuesday. In particular the question of the u/d mass difference,  
> about which the theory reviewers seem to disagree about the way you  
> plan to measure it from the data.
>
> 2. It is not clear to me what physics conclusions can be drawn from  
> the measurement of the photoproduction cross section. As you point  
> out the four predictions in Fig. 15 are all consistent with each  
> other, so it is not clear to me how effective the measurements will  
> be in distinguishing between the various models, with the exception  
> of the dashed red curve (by the way, what model does it correspond  
> to ? Is it the VMD calculation ?). Also if I look at Fig. 18, which  
> shows calculations for various cascade production channels, I note  
> that for the only channel for which there are experimental data they  
> agree pretty well with the theory calculation: what are you  
> expecting to find when you measure the other channels ?
>
> 3. What level of simulation was used in the estimation of  
> backgrounds (pp. 41-43) ? You mention fast simulation (with  
> parametrized detector response): was a full event reconstruction  
> performed or was the Monte Carlo truth used in the background  
> estimations ? Is a full simulation foreseen ?
>
> 4. For the determination of the spin/parity quantum numbers (which  
> is a crucial measurements if one aims at having a complete picture  
> of the cascade spectrum) the DMA method is illustrated, but there is  
> no quantitative discussion of the actual number of events needed to  
> make this measurement in CLAS12, beyond the rather generic statement  
> that large statistics will be collected in the relevant cascade  
> production channels. I think that this measurement proposal should  
> be supported by a more quantitative discussion and possibly a full  
> simulation to demonstrate its feasibility in CLAS12. Also: have  
> other methods to measure J^P been considered ? (e.g. Dalitz analysis).
>
> 5. Is there another advantage in the increased photon energy, beyond  
> the broader kinematical range mentioned at several points in the  
> proposal ? (e.g. observables which have a significant dependance on  
> the photon energy).
>
> 6. A minor point: on page 12 you write that "it seems plausible that  
> the one NA48 high-statistics measurement of the Csi_0 mass could be  
> too low". Why is that so ? Since it is the only high-statistics  
> measurement isn't it plausible that it be the most reliable ?
>
> 7. Do I understand correctly that this proposal does not impose any  
> further requirements on the CLAS12 detector ?
>
> This is all for the moment. I am looking forward to your  
> presentation at the PAC next tuesday.
>
> best regards
> diego
>
>
> -- 
>
> Diego Bettoni
> INFN Ferrara, Director
> Via Saragat, 1
> I-44100 FERRARA
>
> tel: +39-0532-974275
> tel: +39-0532-974332
> fax: +39-0532-974300
>
> web: http://www.fe.infn.it/~bettoni/
>

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