[Clascomment] [EXTERNAL] Re: OPT-IN: First measurement of direct photoproduction of the a2(1320) meson on the proton

[Andrea Celentano]

Dear Axel,
thanks for your comments. I reply to them here:

Line 159: the full CVM for the reaction gamma p -> p gamma gamma gamma gamma is a 16x16 matrix, made of diagonal blocks: there is a single element for the impinging beam photon and 5 3x3 elements, one per each particle. Each element of the matrix is a function of the kinematic variables of the particles it belongs to. To perform a kinematic fit, therefore, one has to define a parameterization of each element as a function of these kinematic variables.
Concerning the beam photon and the proton, I used the same description that was determined from g12. By this I mean both the functional form and the parameters that enters in the function.
Concerning the final state photons, I determined the CVM block in my analysis.
To clarify, I think that I can use the following in line 159: To this end, the default g12 covariance matrix (CVM) elements for the beam photon and for the final state proton was used. The final state photons CVM elements, instead, …
There is a repetition for “elements”, but this makes more clear.

Line 180: I prefer to keep it as it is, since the word “aiding” seems to suggest that there is another step in the analysis devoted to the selection of the exclusive final state.

Line 183, 215, 216, 219: I implemented all the corrections and suggestions.

Thanks again,
Bests,
Andrea
> On Apr 1, 2020, at 23:38, Axel Schmidt <schmidta at jlab.org> wrote:
> 
> Dear Andrea et al.,
> 
> Nice job on this result. I enjoyed reading the paper. There are some things that I noticed, which I hope are helpful to you. Best of luck as  you go through peer review.
> 
> Best regards,
> 
> Axel
> 
> 
> 
> Line 159
> 
> There's some confusion here about the CVM parameterization and the values of the CVM elements. I assume the CVM elements are parameterized functions of theta, phi, E. You seem to suggest that the parameterization is preserved only for the incoming photon and final state proton. Then you say new "CVM elements" were determined for the final state photons?
> 
> What is actually being preserved from the g12 defaults? The parameterization? The parameter values? I don't know if it's a relevant detail, but it could be stated less ambiguously.
> 
> 
> Line 180
> 	"Other than selecting exclusive events..."
> 	->
> 	"In addition to aiding exclusive event selection, the kinematic fit significantly improves the experimental resolution."
> 
> 
> Line 183
> 	"The kinematic fit discussed before selected..."
> 	->
> 	"The kinematic fit discussed above ...
> 		(and I'd even change to "...was used to select...")
> 
> Line 215
> 	"assigns" -> "assign"
> 
> Line 216
> 	"associated to" -> "associated with"
> 
> Line 219
> 	"control variable" -> "control variables"
> 
> 
> 

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