Study of χc2 production in photon-photon collisions

doi:10.1016/0370-2693(93)90407-9

Physics Letters B

Volume 302, Issues 2–3, 25 March 1993, Pages 345-350

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Abstract

Two-photon production of the charmonium state χ_c has been studied by the TPC/Two-Gamma experiment at the SLAC e⁺e⁻ collider PEP. We observe evidence of the χ_c2 state in the channel γγ→χ_c2, χ_c2→γJ/ψ, J/ψ→l⁺l⁻ and obtain a value of Γ_γγ(χ_c2)=3.4±1.7±0.9 keV. This is the first observation of the two-photon production of a χ_c state. Comparison is made with previous experimental results and QCD predictions for Γ_γγ(χ_c2).

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A concise summary of recent experimental data presented at this conference illustrates the progress in our understanding of the photon interactions. The perturbative QCD domain of high Q² two-photon events and high p_t jet production in both γγ and eγ interactions is well described by NLO calculations and parton density functions. Measurements of diffractive processes and resonance formation provide a detailed information on the difficult field of long range strong interaction forces.

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^☆: This work was supported in part by the US Department of Energy (under contracts DE-FG03-91ER40674, DE-AS03-76ER70285, DE-FG03-91ER40662, DE-AT03-87ER40327, DE-AM03-76SF00010, DE-AC03-76SF00098, DE-FG02-92ER40730, DE-FG02-92ER40715, and DE-AC03-76SF00515), and the National Science Foundation (under grants PHY91-19849 and PHY91-21416).

¹: We gratefully acknowledge the efforts of the PEP staff for their dedication and productive running of the machine, and the engineers and technicians of the collaborating institutions for their efforts in the construction and maintenance of the detector.

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Study of χc2 production in photon-photon collisions☆

Abstract

Stanford University thesis

Phys. Rev. Lett.

Phys. Rev. D

Phys. Rep.

Phys. Rev. D

Intern. J. Mod. Phys. A

Phys. Rev. D

Annu. Rev. Nucl. Part Sci.

Z. Phys. C

Phys. Rev. D

Oak Ridge report ORNL-CCIP-92-05

Phys. Rep.

Study of χ_c2 production in photon-photon collisions☆