Identifying the transverse and longitudinal modes of the and mesons through their angular-dependent decay modes

及び中間子の縦方向及び横方向のモードを崩壊モードの角度依存により分類する研究

Park, I. W.*; 佐甲 博之   ; 青木 和也*; Gubler, P. ; Lee, S. H.*

Park, I. W.*; Sako, Hiroyuki; Aoki, Kazuya*; Gubler, P.; Lee, S. H.*

Observing the mass shifts of chiral partners will provide invaluable insight into the role of chiral symmetry breaking in the generation of hadron masses. Because both the and mesons have vacuum widths smaller than 100 MeV, they are ideal candidates for realizing mass shift measurements. On the other hand, the different momentum dependence of the longitudinal and transverse modes smear the peak positions. In this work, we analyze the angular dependence of the two-body decays of both the and . It is found that the longitudinal and transverse modes of the can be isolated by observing the pseudoscalar decay in either the forward or perpendicular directions, respectively. For the decaying into a vector meson and a pseudoscalar meson, one can accomplish the same goal by further observing the polarization of the vector meson through its angular dependence on the two pseudoscalar meson decay.