[Clascomment] OPT-IN:Differential cross section of gamma n --> K+ Sigma- on bound neutron with incident photons from 1 to 3.6 GeV

[Giovanetti]

From: "Kei Moriya" <kmoriya at andrew.cmu.edu>
Sent: Wednesday, November 25, 2009 1:21 PM
Subject: OPT-IN:Differential cross section of gamma n --> K+ Sigma- on bound 
neutron with incident photons from 1 to 3.6 GeV


>
> Dear Sergio et al.,
>
> I read your paper with interest, and I think it shows
> some good data for the differential cross sections.
>
> I have a few comments:
>
> p.2 right 4th para. \"the Sigma*(1385)- decays into Sigma- pi0 with 
> bSigma* ~ 12%\"
>
> I would assume that the Sigma(1385)- would also go to Sigma0 pi-, so 
> change
> the br appropriately, or quote as \"decays into (Sigma pi)- with bSigma* ~ 
> 12%\".
> Or by \"bSigma*\" do you mean BR(Sigma(1385)- -> (Sigma pi)-)? I think 
> this is not clear.
>
> p.2 right 4th para. \"the K*(892)+ decays into K+ pi0 with bK*~100%\".
>
> Again, the K*+ will have a decay mode into K0 pi+, so either correct
> the br or quote as (K pi)+.
>
> p.2 4th para. \"Events with a spectator proton were selected by applying
> a 3sigma cut around the main peak.\"
>
> In Fig 1 it seems the cut aorund the proton peak excludes a lot of
> the tails. Does \"3 sigma\" mean \"+/- 1.5 sigma on both sides\"?
> If so, I would think \"+/-1.5 sigma cut around the peak\" would be
> less confusing.
>
> Also, I understand that the high side of the peak is
> contaminated by background channels, but is it possible
> to use the lower side that is excluded by your cut?
> It seems to be well fit with just your Gaussian.
>
> p.2 4th para. \"Each distribution was fitted with a Lorentzian peak\"
>
> Why is a Lorentzian used for a peak that has no intrinsic width (Sigma-)?
> A Gaussian or Voigtian would seem a less confusing choice, although the
> fit in Fig 2 seems pretty decent.
>
> Best regards,
>          Kei Moriya
>
>
>