[Paper Review] Nonperturbative QCD Effects in High Energy Collisions

Otto Nachtmann|arXiv (Cornell University)|Nov 21, 1994

Quantum Chromodynamics and Particle Interactions5 references3 citations

TL;DR

This paper proposes a field-theoretic approach using the stochastic vacuum model to calculate nonperturbative QCD effects in high-energy hadron-hadron collisions. It achieves good agreement with experimental data for elastic scattering and suggests that spin effects in the Drell-Yan process may provide evidence for nonperturbative QCD effects in hard collisions.

ABSTRACT

High energy hadron-hadron collisions are discussed. It is argued that soft collisions should involve in an essential way nonperturbative QCD. A way is outlined how to calculate properties of high energy elastic hadron-hadron scattering using field theoretic methods. The functional integrals occuring there are evaluated using the ``stochastic vacuum model''. A satisfactory comparison between theory and experiment is achieved. Then the question of possible nonperturbative QCD effects in high energy hard hadron-hadron collisions is raised. It is shown that some spin effects in the Drell-Yan process may give a hint that such effects exist indeed in nature.

Motivation & Objective

• To develop a field-theoretic framework for describing nonperturbative QCD effects in high-energy hadron-hadron scattering.
• To apply the stochastic vacuum model to evaluate functional integrals arising in the theory.
• To test the model's predictions against experimental data on elastic hadron-hadron scattering.
• To investigate whether nonperturbative QCD effects could influence high-energy hard processes, such as the Drell-Yan process.
• To explore potential signatures of nonperturbative dynamics in spin-dependent observables of the Drell-Yan process.

Proposed method

• Formulates high-energy hadron-hadron scattering in terms of functional integrals within quantum field theory.
• Applies the stochastic vacuum model to nonperturbatively evaluate the functional integrals.
• Uses the model to compute properties of elastic scattering amplitudes in the high-energy limit.
• Compares theoretical predictions with experimental data on total and differential cross sections.
• Analyzes spin asymmetries in the Drell-Yan process as a probe for nonperturbative QCD effects.
• Relies on field-theoretic methods without perturbative expansions, focusing on nonperturbative vacuum structure.

Experimental results

Research questions

• RQ1 Can the stochastic vacuum model provide a consistent nonperturbative description of high-energy elastic hadron-hadron scattering?
• RQ2 To what extent do nonperturbative QCD effects influence the dynamics of hard hadron-hadron collisions?
• RQ3 Are there observable signatures of nonperturbative QCD in spin-dependent processes like the Drell-Yan reaction?
• RQ4 How well does the field-theoretic framework based on the stochastic vacuum model reproduce experimental data?
• RQ5 What role does the nonperturbative structure of the QCD vacuum play in high-energy scattering amplitudes?

Key findings

• The stochastic vacuum model yields a satisfactory quantitative comparison with experimental data on high-energy elastic hadron-hadron scattering.
• The model successfully describes the total and differential cross sections in elastic scattering without relying on perturbative QCD.
• Spin asymmetries in the Drell-Yan process are identified as a potential observable signal for nonperturbative QCD effects.
• The results suggest that nonperturbative QCD effects may play a measurable role even in high-energy hard processes.
• The framework provides a nonperturbative, field-theoretic alternative to traditional parton model approaches for high-energy hadronic collisions.
• The agreement with data supports the validity of the stochastic vacuum model as a tool for nonperturbative QCD calculations.