7-12 June 2021
Europe/Paris timezone

The study on the medium parton distribution from momentum kick model in Heavy-Ion Collisions

Jun 10, 2021, 6:45 PM


Theory poster Heavy Ions Poster Session


Soyeon Cho (Inha University (KR))


The ridge-like structure found in two-particle correlation from the proton-proton collision is one of the hot topics in high-energy heavy-ion physics. Since the medium produced from pp collision is not large enough to generate a high-temperature and high-density medium, called QGP, and therefore this phenomenon can not be suitablely understood through hydrodynamics, unlike in nucleus-nucleus collision.Jet particles lose a considerable amount of energy while they move through the collisions with partons in the medium. The momentum transferred from jets to medium partons are in the direction of jets’ motion, which might produce the collective motion of the medium such as the ridge. In this sense, the momentum kick model has been tested in nucleus-nucleus and pp collisions at various energies. [1]
In this model, the initial parton distribution of the medium is necessary to describe the scattering process kinematically. We have adopted several distribution functions: Maxwell-Boltzmann(MB), Juttner-Synge(JS), and phenomenological parton distribution functions from the soft scattering model (phPDs). However, the MB and JS can not explain a wide range of pseudo-rapidity in the Ridge structure. Therefore we study the phPDs relatively in detail.
The phPDs is parameterized with two variables: the temperature of the medium and a fall-out parameter which determines the decreasing slope at a high-rapidity region. The temperature of the medium critically contibute on the pT distribution while the fall-out parameter on the rapidity distribution. These parameters are determined from the experimental data for pp or AA collisions. [2]
Recently, this model has been used to describe the experimental data for LHC energies, using the parameters fitted to RHIC data, whose energies are 100 times less than LHC energies. Therefore the new study is necessary for the parameter settings for LHC energies.
In this study, we fitted to the simulated data for pp collisions at sqrt{sNN} = 2.76TeV using PYTHIA and new values are quite different from those for low energy data. We compare not only the pT and rapidity distribution but also the lightcone variable distribution. Using these settings, we tried to calculate the two-particle correlations and compare them to the experimental results.

[1] C. Y. Wong, Physical Review C 85, 064909 (2012)
[2] C. Y. Wong, Physical Review C 78, 064905 (2008)
[3] Huh, K. B., Cho, S., Ko, G., & Yoon, J. H. (2018). Two-particle correlation via Bremsstrahlung.
[4] Kim, B., Youn, H., Cho, S. et al. Momentum-Kick Model Application to High-Multiplicity pp Collisions at s√=13 TeV at the LHC. Int J Theor Phys (2021).

Primary authors

Soyeon Cho (Inha University (KR)) Prof. Jin Hee Yoon (Inha University (KR))

Presentation materials