How cross section fluctuations affect multiplicity and geometry in pA collisions

Area of Science:

• High Energy Physics
• Nuclear Physics
• Particle Physics

Background:

• Proton-nucleus (pA) collisions are crucial for understanding nuclear matter.
• Existing models for pA collisions require further refinement to accurately describe experimental data.

Purpose of the Study:

• To develop a new Monte Carlo Glauber model for pA collisions.
• To incorporate state-of-the-art hadronic cross sections from the KMR model (SHRiMPS) into the Glauber framework.
• To investigate the impact of these cross sections on multiplicity distributions and spatial anisotropy.

Main Methods:

• Development of a Monte Carlo Glauber model.
• Utilizing hadronic cross sections calculated by the KMR model, implemented in the SHRiMPS module of the SHERPA event generator.
• Comparing model results with a Black Disk model and a color fluctuation model.

Main Results:

• The KMR/SHRiMPS cross sections provide excellent descriptions of multiplicity distributions in pA collisions.
• The model exhibits a long tail in the wounded nucleon distribution.
• The model increases the anisotropy in the spatial distribution of wounded nucleons.

Conclusions:

• The new Monte Carlo Glauber model, using KMR/SHRiMPS cross sections, offers a significant improvement for describing pA collisions.
• The model's ability to capture multiplicity distributions and enhance spatial anisotropy is vital for understanding initial states in pA collisions.
• The framework is readily generalizable to nucleus-nucleus (A+A) collisions.