Dominant spin-orbit effects in radiative decays
نویسنده
چکیده
We show that there are two reasons why the partial width for the transition 1ð ð3SÞ ! þ b1ð1PÞÞ is suppressed. First, the spin-averaged matrix element Ið3Sjrj1PJÞ is small, being equal to 0:023 GeV 1 in our relativistic calculations. Secondly, the spin-orbit splittings produce relatively large contributions, giving Ið3Sjrj1P2Þ 1⁄4 0:066 GeV , while due to a large cancellation the matrix element Ið3Sjrj1P1Þ 1⁄4 0:020 GeV 1 is small and negative; at the same time the magnitude of Ið3Sjrj1P0Þ 1⁄4 0:063 GeV 1 is relatively large. These matrix elements give rise to the following partial widths: 2ð ð3SÞ ! þ b2ð1PÞÞ 1⁄4 212 eV, 0ð ð3SÞ ! þ b0ð1PÞÞ 1⁄4 54 eV, which are in good agreement with the CLEO and BABAR data, and also to 1ð ð3SÞ ! þ b1ð1PÞÞ 1⁄4 13 eV, which satisfies the BABAR limit, 1ðexpÞ< 22 eV.
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