Hadronic Nucleus-Nucleus Cross Section and the Nucleon Size

Area of Science:

• High-energy nuclear physics
• Quantum chromodynamics
• Particle physics

Background:

• The total hadronic nucleus-nucleus cross section is a fundamental observable in high-energy nuclear physics.
• Recent precise measurements at the Large Hadron Collider (LHC) for lead-lead collisions provide new constraints.
• Existing Bayesian estimates for nucleon width are challenged by these new experimental results.

Purpose of the Study:

• To investigate the implications of a reduced nucleon width on the properties of quark-gluon plasma (QGP).
• To assess the impact of this smaller nucleon width on theoretical models describing heavy-ion collisions.
• To explore how a refined nucleon width affects key QGP characteristics like bulk viscosity.

Main Methods:

• Analysis of experimental data from lead-lead collisions at the LHC.
• Comparison of experimental results with theoretical predictions based on varying nucleon width parameters.
• Theoretical modeling of QGP properties using updated nucleon width constraints.

Main Results:

• The precise LHC measurements imply a nucleon width significantly smaller than current Bayesian estimates (< 0.7 fm).
• A smaller nucleon width leads to a dramatically improved description of several triple-differential observables.
• This suggests a potential revision of our understanding of nucleon structure and its role in QGP formation.

Conclusions:

• The new experimental constraints on nucleon width necessitate a re-evaluation of existing theoretical frameworks.
• The improved agreement with experimental data highlights the importance of precise nucleon width in QGP studies.
• Future research should focus on reconciling experimental findings with theoretical models to better understand the QGP and nucleon structure.