We study spin-spin entanglement in the final state photon-nucleon system in Compton scattering, both at low energy below the pion threshold and at high energy in perturbative QCD to next-to-leading order. We first establish a no-go theorem showing that, for any spin-$\frac{1}{2}$ target, entanglement cannot be generated in unpolarized Compton scattering if the scattering amplitudes are real. We then consider polarized Compton scattering off the electron, the proton and the neutron. At low energy, we uncover a rich variety of maximally entangled Bell states and their unitary equivalents realized across different regions of the kinematic plane. Interestingly, the proton and neutron targets exhibit distinct patterns of entanglement. In the neutron case, the electric and magnetic polarizabilities dramatically influence the pattern and even the existence of entanglement. This suggests that entanglement can serve as a novel tool for investigating the detailed electromagnetic properties of the nucleons.
Spin correlations offer a quantum-information perspective on the partonic final states produced in high-energy scattering. We discuss the spin-density matrix of a heavy quark-antiquark pair in two complementary small-$x$ processes. In coherent diffractive production, color-singlet exchange enforces an unusually strong...
M. Fucilla, Yoshitaka Hatta, Bo-Wen Xiao· 0 citations
We discuss the feasibility of quantum spin-state teleportation in a three-proton system at an energy of 151 MeV, where, similarly to the low-energy case, a single Bell-state term dominates the proton-proton scattering matrix. We find that, in contrast to the low-energy regime, where unpolarized proton-proton scattering...
Low-energy lepton-nucleon scattering probes various expressions of the long-distance dynamics in the baryon sector of QCD, governed by chiral symmetry breaking and the $\Delta$ resonance. We discuss some specific studies that could be performed with combined electron- and positron-nucleon scattering at lab energies $E_...
We compute quark and meson spectral functions in low-energy QCD, including all-order scatterings and decays of pions and the scalar $\sigma$-mode. For low energies the gluons decouple and the dynamics of two-flavour QCD is well-described by a Quark-Meson model. The computations are performed directly in Minkowski space...
Konrad Kockler, J. M. Pawlowski, Franz R. Sattler et al.· 0 citations
We investigate quark-antiquark entanglement in heavy quarkonium within a nonperturbative light-front Hamiltonian framework. By tracing over the antiquark degrees of freedom in the hadronic state vector, we construct the reduced density matrix of the quark subsystem and compute the associated von Neumann entropy. For sp...
Wenyu Zhang, Yiyu Zhou, Yang Li et al.· 1 citation
Low-energy $s$-wave scattering in weakly bound superfluid nuclei is strongly influenced by pairing correlations. In this work, we present an analytical study of low-energy $s$-wave quasiparticle scattering within the coordinate space Hartree-Fock-Bogoliubov framework using a schematic square-well model. Analytical expr...
Y. Kobayashi, M. Matsuo· 0 citations
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