Towards the determination of CP-odd pion-nucleon couplings
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866908295748386816 |
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| author | Bhattacharya, Shohini Fuyuto, Kaori Mereghetti, Emanuele Richardson, Thomas R. |
| author_facet | Bhattacharya, Shohini Fuyuto, Kaori Mereghetti, Emanuele Richardson, Thomas R. |
| contents | The nucleon matrix elements (NMEs) associated with quark chromo-magnetic dipole moments (cMDMs) play a crucial role in determining the CP-odd pion-nucleon couplings induced by quark chromo-electric dipole moments. In recent years, it has been argued that the NMEs of cMDMs can be related to the third moment of the nucleon's higher-twist (specifically, twist-three) parton distribution function (PDF) $e(x)$, which can, in principle, be measured through dihadron production in semi-inclusive deep inelastic scattering processes. By applying the spin-flavor expansion to the cMDM operators in the large-$N_c$ limit, where $N_c$ is the number of quark colors, we show that the NMEs receive contributions not only from the twist-three PDF $e(x)$ but also from an additional, previously neglected nucleon form factor. Incorporating constraints from the spin-flavor expansion, recent experimental data on $e(x)$, as well as model calculations of $e(x)$, we estimate the NMEs of the cMDM operators. Our analysis indicates that the NMEs are dominated by the nucleon form factors, and the cMDM contributions to pion-nucleon couplings can be comparable to those from the quark sigma terms. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2504_01105 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Towards the determination of CP-odd pion-nucleon couplings Bhattacharya, Shohini Fuyuto, Kaori Mereghetti, Emanuele Richardson, Thomas R. High Energy Physics - Phenomenology High Energy Physics - Lattice Nuclear Experiment Nuclear Theory The nucleon matrix elements (NMEs) associated with quark chromo-magnetic dipole moments (cMDMs) play a crucial role in determining the CP-odd pion-nucleon couplings induced by quark chromo-electric dipole moments. In recent years, it has been argued that the NMEs of cMDMs can be related to the third moment of the nucleon's higher-twist (specifically, twist-three) parton distribution function (PDF) $e(x)$, which can, in principle, be measured through dihadron production in semi-inclusive deep inelastic scattering processes. By applying the spin-flavor expansion to the cMDM operators in the large-$N_c$ limit, where $N_c$ is the number of quark colors, we show that the NMEs receive contributions not only from the twist-three PDF $e(x)$ but also from an additional, previously neglected nucleon form factor. Incorporating constraints from the spin-flavor expansion, recent experimental data on $e(x)$, as well as model calculations of $e(x)$, we estimate the NMEs of the cMDM operators. Our analysis indicates that the NMEs are dominated by the nucleon form factors, and the cMDM contributions to pion-nucleon couplings can be comparable to those from the quark sigma terms. |
| title | Towards the determination of CP-odd pion-nucleon couplings |
| topic | High Energy Physics - Phenomenology High Energy Physics - Lattice Nuclear Experiment Nuclear Theory |
| url | https://arxiv.org/abs/2504.01105 |