[Clascomment] OPT-IN:Measurements of $gamma_{v} p ightarrow p' pi^{+} pi^{-}$ cross section with the CLAS detector for $0.4 GeV^{2} < Q^{2} < 1.0 GeV^2$ and $1.3 GeV < W <1.825 GeV$

[Viktor Mokeev]

Dear Dave,

 In regards of your bullet mentioning the use of inclusive rad. correction. We do have a fully exclusive approach to radiative correction in Npi channels, developed bu V.D.Burkert, A.Afanasev, K.Joo, et al. It incorporates known hadronic tensor for external rad correction. Studies of single pion channels demonstrated that impact of hadronic tensor dependence on the final hadron kinematics decreases if we integrate over the final state kinematic variables by a factor of two per integration, at least. The Npipi cross sections we reported represent 4d integrals from 5d cross section. Therefore, the impact of the final hadron state on rad processes for our cross section should be decreased by a very large factor. It justifies, in my view, the use of Mo ans Tsai rad procedure for our 1d cross sections which are 4d integrals.

   Best Regards,
                       Victor 

----- Original Message -----
From: "David Ireland" <David.Ireland at glasgow.ac.uk>
To: "clasmbr" <clasmbr at jlab.org>, "clascomment" <clascomment at jlab.org>, "burkert" <burkert at jlab.org>, "Kenneth Hicks" <hicks at ohio.edu>, "Viktor Mokeev" <mokeev at jlab.org>, "Marco Ripani" <Marco.Ripani at ge.infn.it>, "Gleb Fedotov" <gleb at jlab.org>, "Ralph Gothe" <gothe at jlab.org>, "Nick Markov" <markov at jlab.org>, "skorodum" <skorodum at jlab.org>, whit at jlab.org
Sent: Monday, February 19, 2018 5:21:11 AM
Subject: OPT-IN:Measurements of  $gamma_{v} p  ightarrow p' pi^{+} pi^{-}$ cross section with the CLAS detector  for $0.4 GeV^{2} < Q^{2} < 1.0 GeV^2$ and $1.3 GeV < W <1.825 GeV$

Dear Gleb, et al.,

I have just a few comments on the draft paper, which looks to be in good shape:

- line 24: referencing the CLAS technical paper is better left to the experimental section; it is more important to reference some physics results, such as the previous measurements that are described.

- lines 34-37: again, these sentences belong in the experimental section 

- figure 15: This figure is a little confusing. Is it not enough to simply state that cells with $\delta\epsilon/\epsilon$ greater than 0.3 were not included because of concern over statistical accuracy?

- line 799-802: I am not sure that, just because an approach for describing radiative processes in exclusive double-pion electroproduction is not available, it follows that a simpler assumption is adequate.

Some re-wording maybe better, what about "The latter assumption is necessary, since approaches that are capable of describing radiative processes in double-pion electroproduction are not yet available."


Cheers,

Dave