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Entanglement, partial set of measurements, and diagonality of the density matrix in the parton model
by Haowu Duan
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Submission summary
| Authors (as registered SciPost users): | Haowu Duan |
| Submission information | |
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| Preprint Link: | https://arxiv.org/abs/2107.10812v2 (pdf) |
| Date accepted: | 2022-03-01 |
| Date submitted: | 2022-02-14 18:54 |
| Submitted by: | Duan, Haowu |
| Submitted to: | SciPost Physics Proceedings |
| Proceedings issue: | 28th Annual Workshop on Deep-Inelastic Scattering (DIS) and Related Subjects (DIS2021) |
| Ontological classification | |
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| Academic field: | Physics |
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| Approach: | Phenomenological |
Abstract
To study quantum properties of the hadron wavefunction at small x, we derived the reduced density matrix for soft gluons in the CGC framework. We explicitly showed that the reduced density matrix is not diagonal in the particle number basis. The off-diagonal components are usually ignored in the conventional parton model. We thus defined the density matrix of ignorance by keeping only the part of the reduced density matrix which can be probed in a limited set of experimental measurements. We calculated Von Neumann entropy for both the reduced and ignorance density matrices. The entropy of ignorance is always greater than the entanglement entropy (computed drom the reduced density matrix) of gluons. Finally, we showed that the CGC reduced density matrix for soft gluons can be diagonalized in a thermal basis with Boltzmann weights suggesting thermalization of new quasi-particle states which we dubbed entangolons.
Published as SciPost Phys. Proc. 8, 160 (2022)