Direct pion emission in D＊＋ → D＋π decays
The QCD multipole expansion （QCDME） is based on quantum field theory and has been extensively applied to study transitions among Y and ψ family members. As it refers to non-perturbative QCD, however, it has only a certain application range. Even though it successfully explains the transition data am...
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| Published in | Chinese physics C Vol. 40; no. 7; pp. 22 - 27 |
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| Main Author | |
| Format | Journal Article |
| Language | English |
| Published |
01.07.2016
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| Subjects | |
| Online Access | Get full text |
| ISSN | 1674-1137 2058-6132 0254-3052 |
| DOI | 10.1088/1674-1137/40/7/073103 |
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| Summary: | The QCD multipole expansion （QCDME） is based on quantum field theory and has been extensively applied to study transitions among Y and ψ family members. As it refers to non-perturbative QCD, however, it has only a certain application range. Even though it successfully explains the transition data among members of the T （ψ ） family, as Eichten indicates, beyond the production threshold of mediate states it fails to match data by several orders of magnitude. In this work, by studying a simple decay mode D＊ → D ＋ π, where a pion may be emitted before D＊ transitions into D, we analyze the contribution of QCD multipole expansion. As the Dπ portal is open, the dominant contribution is an OZI-allowed process where a light quark-pair is excited out from vacuum, and its contribution can be evaluated by the 3P0 model. Since direct pion emission is OZI-suppressed and violates isospin conservation, its contribution must be much smaller than the dominant one. By a careful calculation, we estimate that the QCDME contribution should be 34 orders smaller than the dominant contribution and this result can offer a quantitative interpretation for Eichten＇s statement. |
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| Bibliography: | Xing-Dao Guo Xue-Wen Liu Hong-Wei Ke Xue-Qian Li（ 1 School of Physics, Nankai University, Tianjin 300071, China 2 Department of Physics, Tianjin University, Tianjin 300072, China） 11-5641/O4 The QCD multipole expansion （QCDME） is based on quantum field theory and has been extensively applied to study transitions among Y and ψ family members. As it refers to non-perturbative QCD, however, it has only a certain application range. Even though it successfully explains the transition data among members of the T （ψ ） family, as Eichten indicates, beyond the production threshold of mediate states it fails to match data by several orders of magnitude. In this work, by studying a simple decay mode D＊ → D ＋ π, where a pion may be emitted before D＊ transitions into D, we analyze the contribution of QCD multipole expansion. As the Dπ portal is open, the dominant contribution is an OZI-allowed process where a light quark-pair is excited out from vacuum, and its contribution can be evaluated by the 3P0 model. Since direct pion emission is OZI-suppressed and violates isospin conservation, its contribution must be much smaller than the dominant one. By a careful calculation, we estimate that the QCDME contribution should be 34 orders smaller than the dominant contribution and this result can offer a quantitative interpretation for Eichten＇s statement. QCDME, D＊ decay, 3p0 model |
| ISSN: | 1674-1137 2058-6132 0254-3052 |
| DOI: | 10.1088/1674-1137/40/7/073103 |