Experimental Investigation of the Two-Photon Widths of the $χ_{c 0}$ and the $χ_{c 2}$ Mesons

Using

12.7 {fb}^{- 1}

of data collected with the CLEO detector at CESR, we observed two-photon production of the

c \bar{c}

states

χ_{c 0}

and

χ_{c 2}

in their decay to

π^{+} π^{-} π^{+} π^{-}

. We measured

Γ_{γ γ} (χ_{c}) \times B (χ_{c} \to π^{+} π^{-} π^{+} π^{-})

to be

75 \pm 13 (stat) \pm 8 (syst) eV

for the

χ_{c 0}

and

6.4 \pm 1.8 (stat) \pm 0.8 (syst) eV

for the

χ_{c 2}

, implying

Γ_{γ γ} (χ_{c 0}) = 3.76 \pm 0.65 (stat) \pm 0.41 (syst) \pm 1.69 (br) keV

and

Γ_{γ γ} (χ_{c 2}) = 0.53 \pm 0.15 (stat) \pm 0.06 (syst) \pm 0.22 (br) keV

. Also, cancellation of dominant experimental and theoretical uncertainties permits a precise comparison of

Γ_{γ γ} (χ_{c 0}) / Γ_{γ γ} (χ_{c 2})

, evaluated to be

7.4 \pm 2.4 (stat) \pm 0.5 (syst) \pm 0.9 (br)

, with QCD-based predictions.

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Experimental Investigation of the Two-Photon Widths of theχc0and theχc2Mesons