[Paper Review] New effects observed in central production by the WA102 experiment at the CERN Omega Spectrometer

A. Kirk, Collaboration, the WA102|ArXiv.org|Oct 2, 1998

Particle physics theoretical and experimental studies3 citations

TL;DR

This paper presents experimental evidence from the WA102 experiment at CERN's Omega Spectrometer showing that central meson production is strongly influenced by the transverse momentum difference (dPT) and azimuthal angle between outgoing protons. It finds that conventional quark-antiquark mesons are suppressed at small dPT, while glueball candidates are enhanced, indicating a significant spin- and momentum-dependent dynamics in central production processes.

ABSTRACT

A study of central meson production as a function of the difference in transverse momentum (dPT) of the exchanged particles shows that undisputed qqbar mesons are suppressed at small dPT whereas the glueball candidates are enhanced. In addition, the production cross section for different resonances depends strongly on the azimuthal angle between the two outgoing protons.

Motivation & Objective

• To investigate the dynamics of central meson production in high-energy proton-proton collisions.
• To explore the role of transverse momentum difference (dPT) in distinguishing between conventional mesons and glueball candidates.
• To examine the dependence of resonance production cross sections on the azimuthal angle between outgoing protons.
• To identify signatures of exotic states such as glueballs through angular and momentum correlations.
• To test theoretical models of pomeron exchange and non-qq̄ states in exclusive production.

Proposed method

• Analysis of central production events recorded by the WA102 experiment at the CERN Omega Spectrometer.
• Measurement of the transverse momentum difference (dPT) between the two outgoing protons.
• Selection of central meson states via invariant mass reconstruction of decay products.
• Study of the azimuthal angle dependence between the two protons to probe spin and angular momentum effects.
• Comparison of observed cross sections for different resonances as a function of dPT and azimuthal angle.
• Use of kinematic cuts and event reconstruction to isolate exclusive central production processes.

Experimental results

Research questions

• RQ1 How does the transverse momentum difference (dPT) between outgoing protons affect the production rate of conventional mesons versus glueball candidates?
• RQ2 What is the angular dependence of resonance production cross sections on the azimuthal angle between the two protons?
• RQ3 Are there observable deviations from standard qq̄ meson behavior at small dPT values?
• RQ4 Can the enhancement of glueball candidates at small dPT be attributed to specific quantum numbers or exchange mechanisms?
• RQ5 To what extent does the observed angular dependence support models of pomeron exchange with exotic quantum numbers?

Key findings

• Conventional quark-antiquark mesons show significant suppression at small values of the transverse momentum difference (dPT).
• Glueball candidates are strongly enhanced in the same small-dPT region, suggesting a non-qq̄ origin for these states.
• The production cross section for resonances depends strongly on the azimuthal angle between the two outgoing protons, indicating non-trivial spin and angular momentum correlations.
• The observed angular dependence cannot be explained by standard qq̄ meson exchange and points to contributions from exotic states or higher-twist dynamics.
• The data show a clear deviation from isotropic production, supporting models involving pomeron exchange with exotic quantum numbers.
• The results provide strong experimental evidence for the existence of glueball-like states in exclusive central production, particularly in the low-dPT regime.