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arXiv · 2603.16681

Spin entanglement signatures of proton from a light-front Hamiltonian

Chen Qian·Siqi Xu·Yang-Guang Yang·Xingbo Zhao
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Abstract

Quantum entanglement provides a quantitative probe of the internal structure of hadrons and offers a sensitive means to study the quantum correlation in the hadron wave functions. For baryons, the spin state of the three valence quarks forms a tripartite qubit system, whose entanglement structure can be characterized by the four classes of three-qubit states. In this work, we compare the proton spin entanglement obtained from Basis Light-Front Quantization (BLFQ) with that from a quark-diquark model. By analyzing both bipartite and tripartite entanglement, we find that the quark-diquark model yields a substantially more entangled spin state than the BLFQ wave function in the valence Fock sector. This difference mainly originates from the larger W-type and Bell-type entanglement in the quark-diquark model. Within BLFQ, larger stronger coupling constant and smaller quark mass drive the spin correlation among the valence quarks towards an effective quark-diquark configuration with an active $d$ quark and a correlated $uu$ pair.

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Chen Qian, Siqi Xu, Yang-Guang Yang, Xingbo Zhao. 2026-03-17. Spin entanglement signatures of proton from a light-front Hamiltonian. https://arxiv.org/abs/2603.16681

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