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On connection of the cosmic-ray coplanarity of most energetic particles with the collider long-range near-side "ridge" effect

by Rauf A. Mukhamedshin

Submission summary

Authors (as registered SciPost users): Rauf Mukhamedshin
Submission information
Preprint Link: scipost_202208_00092v1  (pdf)
Date submitted: 2022-08-31 12:36
Submitted by: Mukhamedshin, Rauf
Submitted to: SciPost Physics Proceedings
Proceedings issue: 21st International Symposium on Very High Energy Cosmic Ray Interactions (ISVHECRI2022)
Ontological classification
Academic field: Physics
  • High-Energy Physics - Experiment
  • High-Energy Physics - Phenomenology
Approaches: Experimental, Computational, Phenomenological


Coplanarity of most energetic subcores of $\gamma$-ray--hadron families observed in cosmic-ray experiments at $E_0 \gtrsim 10^{16}$ eV is explained only with a process of coplanar generation of most energetic hadrons. Long-range near-side "ridge" effect at $\sqrt{s} = 7$ TeV was found by the CMS Collaboration in two-particle $\Delta\eta - \Delta\varphi$ correlation functions. The FANSY 2.0 model reproduces both the hadron coplanarity and "ridge" effect.

Current status:
Awaiting resubmission

Reports on this Submission

Anonymous Report 1 on 2022-12-31 (Invited Report)


no particular strengths


See report


The paper by Mukhamedshin about the "connection of the cosmic-ray coplanarity of most energetic particles with the collider long-range near-side 'ridge' effect" follows a sequence of papers by the author on the same topic and an extended version of this proceedings has recently been published in Eur. Phys. J. C (2022) 82:155 and is also listed as reference 17.
Unfortunately, the expectation suggested by the title, namely to learn about a possible connection between cosmic-ray and collider events w.r.t. to coplanarity is not met: the phenomenon of coplanarity in some cosmic ray events is only reported and simulations using the event generator FANSY by the same author are compared to data of the CMS experiment, only. No attempt is made to compare the output of FANSY model with any of the parameters to cosmic ray events. So what is the reader expected to learn about the connection between the two?

On page 2 it is said that the analysis made by CMS in 2010 is repeated in this paper. It is not clear how this has been done. Did the author use public data? If yes, there should be a reference to it.
Moreover, the reference to the CMS 2010 results needs to be updated to
J. High Energ. Phys. 2010, 91 (2010).

In Figure 2, three sets of FANSY simulations are shown using different parameters in the FANSY coplanarity algorithm. The parameters are listed in table 1 and are said to be most important, but the reader does not learn what they actually do, other than increasing or decreasing the coplanarity. So what is the reader expected to learn?

Figure 3 a,b,c, show one set of simulated events and the difference is the width of $Δ\eta$. The author concludes that FANSY predicts a "twin-peak" effect. It seems to the referee (as expected) that a,b,c actually represent the same distributions, only that the entries at large values $Δ\eta$ are cut-off in a and b. Some explanation appears appropriate.

Finally, section 3 discusses that the "CASTOR experiment seems promising" to verify this. To avoid confusion, I suggest to speak of the "CMS-CASTOR very forward calorimeter". A better and much more recent reference than [21] would be doi:10.1088/1748-0221/16/02/P02010.

In summary, the paper does not deliver what the title promises. Also, it remains questionable what one does learn from the paper. Obviously, it is possible to construct an event generator in such a way that it reproduces some features of two particle correlations observed by CMS and other accelerator experiments. However, what does it tell us about the physics and how does it compare to cosmic ray events? Given the fact that this paper represents proceedings to a conference, one probably cannot recommend rejection. At least, the author should address the raised points and apply the corrections to improve the paper.

Requested changes

See report for details

  • validity: low
  • significance: low
  • originality: ok
  • clarity: ok
  • formatting: good
  • grammar: good

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