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Measurement of the chi_{c2} Polarization in psi(2S) to gamma chi_{c2}

M. Ablikim
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Abstract

The polarization of the chi_{c2} produced in psi(2S) decays into gamma chi_{c2} is measured using a sample of 14*10^6 psi(2S) events collected by BESII at the BEPC. A fit to the chi_{c2} production and decay angular distributions in psi(2S) to gamma chi_{c2}, chi_{c2} to pi pi and KK yields values x=A_1/A_0=2.08+/-0.44 and y=A_2/A_0=3.03 +/-0.66, with a correlation rho=0.92 between them, where A_{0,1,2} are the chi_{c2} helicity amplitudes. The measurement agrees with a pure E1 transition, and M2 and E3 contributions do not differ significantly from zero.

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M. Ablikim. 2004-09-11. Measurement of the chi_{c2} Polarization in psi(2S) to gamma chi_{c2}. https://doi.org/10.1103/physrevd.70.092004

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