[Clascomment] OPT-IN: Measurement of Single and Double Spin Asymmetries in Deep Inelastic Pion Electroproduction with Longitudinally Polarized Target

[Mikhail Osipenko]

Dear Authors of SIDIS A1+AUL paper,

first of all I would like to congratulate you with new interesting results.

Below you can find some questions about the presented draft.

With Best Regards,
                     Mikhail.

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1) Systematic errors mensioned on page 2 are probably given in relative to the asymmetry value. While it can be understood for multiplicative factors like the polarization and dilution, it does not make any sense for \"contributions from target fragmentation, kaon contamination and radiative corrections\". The assymetry might well be zero, but the above mentioned uncertainties remain. How were these numbers obtained?

2) Fig.1: what about the other kinematic variables? Is it given at fixed z,P_T or they are integrated over? What is the integration range and average value of each orthogonal variable? Are the average z and P_T different from HERMES?

3) page 2, second column, 3rd paragraph: you quote factor of 3 difference betwee your and HERMES Q2, please add the actual values, otherwise one cannot judge about a possible relevance of 1/Q2 of log(Q2) effects.
                 -                     : you mention 15-20% difference with HERMES data, but from Fig.1 I can\'t find any statistically significant difference. How did you obtain these numbers?

4) page 2, second column, 4th paragraph: the bracket \"(see Fig.2)\" after \"...at moderately small P_T for pi+\" is unnecessary.

5) page 3, first column, paragraph 1: these are probably chi^2/N.d.F, mention the number of degrees of freedom.

6) Fig.2: numbers 0 and 1 on x-axis overlap; pi+ symbol is too high, touching the frame.

7) page 3, first column, paragraph 3: the same objection as above, the only overall multiplicative factors e.g. polarization can be give relative to the asymmetry. Acceptance and, for sure, the difference in + and - luminosities should be in absolute scale. I am wondering why the previously mentioned \"contribution from target fragmentation, kaon contamination and radiative corrections\" do not contribute anymore?

8) page 3, second column, paragraph 2: discussion of rho+p/pi-Delta++ interference is misleading. Since you have applied the cut on the missing mass Mx>1.4 GeV you cannot have this contribution. If you feel that 1.4 GeV cut is not sufficient to remove all the Delta++ please cut at Mx>1.5 GeV. There could be plenty of other mechanisms (higher twists) explaining the difference or even your model can be wrong or not applicable in this kinematic domain.

9) page 4, first column, paragraph 2: the statement about non-zero sin2phi asymmetry seems to be too strong still. Your pi+, pi- and pi0 data are all compatible with zero if you include the systematic errors (except for two first points from pi+, to which you don\'t believe yourself quoting \"the agreement\" with the model). Moreover, what is the reason of the disagreement between these two points and HERMES data? Is is because your systematic unceratinties are underestimated?