[Paper Review] Inclusive distributions at the LHC as predicted from the DPMJET-III model with chain fusion

J. Ranft, Fritz Bopp+2 more|ArXiv.org|Jun 26, 2007

High-Energy Particle Collisions Research11 citations

TL;DR

This paper uses the DPMJET-III model with chain fusion to predict inclusive particle distributions in Pb-Pb collisions at LHC energies. It demonstrates excellent agreement with RHIC data and reveals a simple, universal scaling of mid-rapidity multiplicity per participant pair, supporting the limiting fragmentation hypothesis with minimal deviations in the fragmentation region.

ABSTRACT

DPMJET-III with chain fusion is used to calculate inclusive distributions of Pb-Pb collisions at LHC energies. We present rapidity distributions as well as scaled multiplicities at mid-rapidity as function of the collision energy and the number of participants.

Motivation & Objective

• To model inclusive particle production in central and minimum-bias Pb-Pb collisions at LHC energies using the DPMJET-III framework.
• To implement chain fusion in DPMJET-III to properly describe dense, central heavy-ion collisions.
• To test the validity of the limiting fragmentation hypothesis in high-energy nuclear collisions.
• To investigate the scaling behavior of particle multiplicity distributions with respect to the number of participants and center-of-mass energy.
• To compare model predictions with existing RHIC data and extrapolate to LHC conditions.

Proposed method

• The DPMJET-III Monte Carlo event generator is extended to include percolation and fusion of hadronic chains for central A–A collisions.
• The model combines soft hadronic chain interactions with hard parton-parton scattering, consistent with the dual parton model.
• Inclusive distributions are calculated for rapidity and pseudorapidity, with a focus on mid-rapidity and full pseudorapidity range.
• The quantity $ \frac{dN}{d\eta_{\text{cm}}}/\frac{N_{\text{part}}}{2} $ is used to study scaling behavior across different collision systems and energies.
• The limiting fragmentation hypothesis is tested by plotting $ \frac{dN}{d\eta_{\text{cm}}}/\frac{N_{\text{part}}}{2} $ as a function of $ \eta_{\text{cm}} - y_{\text{beam}} $.
• Simulations are performed for Pb–Pb and Au–Au collisions at RHIC and LHC energies, with comparisons to experimental data.

Experimental results

Research questions

• RQ1 How well does the DPMJET-III model with chain fusion describe inclusive particle distributions in Pb-Pb collisions at LHC energies?
• RQ2 Does the scaled multiplicity $ \frac{dN}{d\eta_{\text{cm}}}/\frac{N_{\text{part}}}{2} $ exhibit universal scaling across different collision energies and participant numbers?
• RQ3 To what extent does the DPMJET-III model satisfy the limiting fragmentation hypothesis in central and less central Au–Au collisions?
• RQ4 What is the behavior of particle production in the fragmentation region, and how do deviations from limiting fragmentation scale with centrality?
• RQ5 How do the model predictions compare quantitatively with existing RHIC data on inclusive distributions?

Key findings

• The DPMJET-III model with chain fusion shows excellent agreement with RHIC data for inclusive distributions in central and minimum-bias collisions.
• The quantity $ \frac{dN}{d\eta_{\text{cm}}}/\frac{N_{\text{part}}}{2} $ exhibits a simple, nearly universal scaling behavior as a function of $ N_{\text{part}} $, independent of collision energy.
• When plotted against $ \eta_{\text{cm}} - y_{\text{beam}} $, the scaled distribution shows only small deviations from the limiting fragmentation hypothesis in the fragmentation region.
• The scaling behavior is consistent across both Pb–Pb and Au–Au collisions at RHIC and LHC energies, indicating robustness of the model's predictions.
• The model successfully captures the transition from soft to hard dynamics in central heavy-ion collisions through chain fusion implementation.
• The results suggest that the limiting fragmentation behavior is approximately valid in high-energy nuclear collisions, even in the presence of strong multiple interactions.