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EPOS4: New theoretical concepts for modeling proton-proton and ion-ion scattering at very high energies
by Klaus Werner
Submission summary
| Authors (as registered SciPost users): | Klaus Werner |
| Submission information | |
|---|---|
| Preprint Link: | https://arxiv.org/abs/2410.09955v3 (pdf) |
| Date accepted: | 2025-01-21 |
| Date submitted: | 2024-12-31 15:06 |
| Submitted by: | Werner, Klaus |
| Submitted to: | SciPost Physics Proceedings |
| Proceedings issue: | 22nd International Symposium on Very High Energy Cosmic Ray Interactions (ISVHECRI 2024) |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
I explain the new concepts underpinning EPOS4, a novel theoretical framework designed to model hadronic interactions at ultrarelativistic energies. This approach eventually reconciles the parallel multiple scattering scenario (needed in connection with collective effects) and factorization (being the conventional method for high-energy scattering).
List of changes
> 1) In the Introduction, the author rightfully argues that the initial stage
> of high energy collisions proceeds on much smaller time-distance scales than
> final state interactions, which allows one to treat the two stages separately.
> However, in lines 17-22, he states that while the initial stage takes a long
> time, the corresponding interaction region is pointlike. This may confuse a
> potential reader. Generally, the size of the interaction region is defined by
> the interaction time. What the author probably means is that while the time
> scale of the initial stage is long enough (and the size of the respective
> region is large enough) to allow for multiple scattering processes to proceed
> in parallel, this time is very short, compared to the characteristic time
> scales of final state interactions. Hence, the interaction region can be
> considered pointlike, compared to the one relevant for final state interactions.
No I don't mean that the time scale of the initial stage is long enough to allow
for multiple scattering processes to proceed in parallel. The actual multiple scattering processes proceed in a very short time interval (considered infinitely small). What takes time is the *preparation*, which at the end provides many partons. The long "preparation" does not allow to have the scatterings one after the other.
I changed the paragraph to make this more clear:
In the diagram, it is evident that a comprehensive representation of space-time must consider the prior splitting of partons (parton evolution). This process (which prepares the actual scattering) takes a long time due to significant γ factors. However, the interaction region (depicted in red) is indeed pointlike, necessitating multiple scatterings to occur simultaneously (the long "preparation" does not allow to have the scatterings one after the other). In the EPOS4 approach for primary interactions, one avoids sequential scatterings for both parton-parton and nucleon-nucleon interactions by rigorously conducting multiple scatterings in parallel. This is true for both, the theoretical formalism and the Monte Carlo realization, based on the principle that the Monte Carlo must be derived directly from theory, which is a non-trivial task.
> 2) Ref. [7] corresponds to the perturbative treatment ('GL' of 'DGLAP')
> rather than to the Gribov-Regge approach.
>
I cannot localize the problem. Yes [7] V. N. Gribov and L. N. Lipatov, , Sov. J. Nucl. Phys. 15, 438 (1972) refers to Gribov stuff. I think I use [7] to refer to this
Current status:
Editorial decision:
For Journal SciPost Physics Proceedings: Publish
(status: Editorial decision fixed and (if required) accepted by authors)