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| Format: | Preprint |
| Veröffentlicht: |
2025
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| Online-Zugang: | https://arxiv.org/abs/2501.04188 |
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| _version_ | 1866918049229045760 |
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| author | Ozcelik, Melih A. |
| author_facet | Ozcelik, Melih A. |
| contents | We present the analytical results for the two-loop form factors needed for $χ_{Q,J}$ production and decay. We consider the two-loop corrections to the process $γγ\leftrightarrow {^3 P_J^{[1]}}$, that has been known only numerically before, and the processes $gg \leftrightarrow {^3 P_J^{[1]}}$, $γg \leftrightarrow {^3 P_J^{[8]}}$ and $gg \leftrightarrow {^3 P_J^{[8]}}$, which have not been computed before. We observe that the NRQCD pole structure of the two-loop amplitude in the $gg$ channel is more involved for the spin-triplet $P$-wave case than for the pseudo-scalar $S$-wave case. It involves in addition to the standard Coulomb singularity also a new singularity whose cancellation requires the inclusion of the $gg \leftrightarrow {^3S_1^{[8]}}$ form factor. We give the high precision numerical results for the hard functions that can be used to compute $χ_{Q,J}$ production and decay up to NNLO accuracy. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_04188 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Two-loop form factors for $P$-wave quarkonium production and decay Ozcelik, Melih A. High Energy Physics - Phenomenology Nuclear Theory We present the analytical results for the two-loop form factors needed for $χ_{Q,J}$ production and decay. We consider the two-loop corrections to the process $γγ\leftrightarrow {^3 P_J^{[1]}}$, that has been known only numerically before, and the processes $gg \leftrightarrow {^3 P_J^{[1]}}$, $γg \leftrightarrow {^3 P_J^{[8]}}$ and $gg \leftrightarrow {^3 P_J^{[8]}}$, which have not been computed before. We observe that the NRQCD pole structure of the two-loop amplitude in the $gg$ channel is more involved for the spin-triplet $P$-wave case than for the pseudo-scalar $S$-wave case. It involves in addition to the standard Coulomb singularity also a new singularity whose cancellation requires the inclusion of the $gg \leftrightarrow {^3S_1^{[8]}}$ form factor. We give the high precision numerical results for the hard functions that can be used to compute $χ_{Q,J}$ production and decay up to NNLO accuracy. |
| title | Two-loop form factors for $P$-wave quarkonium production and decay |
| topic | High Energy Physics - Phenomenology Nuclear Theory |
| url | https://arxiv.org/abs/2501.04188 |