Analysis of γγ → J/ψγ

Abstract

Many models to describe the nature of heavy quarkonia have been proposed and one of the ways to test them is to analyze charmonium states produced in two-photon collisions through measuring their two-photon decay width(Γγγ) and the angular distribution since they provide information on properties and internal structure of charmonium states. In this analysis, we use the decay channel γγ→X→J/ψγ, J/ψ→ℓ+ℓ−(ℓ=eorμ) based on the 980.4 fb−1 Belle data sample, where X is a charmonium state. Previously, Belle and CLEO collaborations have reported measurements of γγ→χc2(1P)→J/ψγ, J/ψ→ℓ+ℓ− using 32.6 fb−1 and 14.4 fb−1 samples, respectively. By analyzing an about 30 times larger data sample, we can make a more precise measurement of χc2(1P) and other rare charmonium states including a new charmonium(-like) state. In this paper, we discuss the proposal and method of the analysis and show the result of the feasibility study using Monte Carlo (MC) samples of γγ→χc2(1P)→J/ψγ.