Angular distributions of the polarized photons and electron in the decays of the state of charmonium

Alex W. K. Mok; Cheuk-Ping Wong; Wai-Yu Sit

doi:10.1140/epjc/s10052-014-2723-8

EPJ

Angular distributions of the polarized photons and electron in the decays of the $$^3D_3$$

state of charmonium

Alex W. K. Mok^*, Cheuk-Ping Wong and Wai-Yu Sit

Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China

Received: 2 October 2013
Accepted: 23 December 2013
Published online: 4 February 2014

Abstract

We calculate the combined angular-distribution functions of the polarized photons ( $\gamma _1$ and $\gamma _2$ ) and electron ( $$e^-$$

) produced in the cascade process $\bar{p}p\rightarrow {^3{D_3}}\rightarrow {^3{P_2}}+\gamma _1 \rightarrow (\psi +\gamma _2)+\gamma _1\rightarrow (e^++e^-)+\gamma _1+\gamma _2$ , when the colliding $\bar{p}$ and $$p$$

are unpolarized. Our results are independent of any dynamical models and are expressed in terms of the spherical harmonics whose coefficients are functions of the angular-momentum helicity amplitudes of the individual processes. Once the joint angular distribution of ( $\gamma _1$ , $\gamma _2$ ) and that of ( $\gamma _2$ , $$e^-$$

) with the polarization of either one of the two particles are measured, our results will enable one to determine the relative magnitudes as well as the relative phases of all the angular-momentum helicity amplitudes in the radiative decay processes ${^3{D_3}}\rightarrow {^3{P_2}}+\gamma _1$ and ${^3{P_2}}\rightarrow \psi +\gamma _2$ .

12 Internat. Congress of the Balkan Physical Union
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EPJ

Angular distributions of the polarized photons and electron in the decays of the state of charmonium

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