Paris nucleon-antinucleon potential constrained by recent antiprotonic-atom data and antineutron-proton total cross sections

Realistic calculations of nuclear disappearance lifetimes induced by neutron-antineutron oscillations

Realistic calculations of nuclear disappearance lifetimes induced by neutron-antineutron oscillations are reported for oxygen and iron, using antineutron nuclear potentials derived from a recent comprehensive analysis of antiproton atomic X-ray and radiochemical data. A lower limit of 3.3 x 10E8 s on the neutron-antineutron oscillation time is derived from the Super-Kamiokande I new lower limit of 1.77 x 10E32 yr on the neutron lifetime in oxygen. Antineutron scattering lengths in carbon and nickel, needed in trap experiments using ultracold neutrons, are calculated from updated antinucleon op…

Nucleon-Antinucleon Annhiliation at Large Nc

Nucleon-antinucleon annihilation in the large $N_c$ limit of QCD in the Witten regime of fixed velocity is considered with a focus on the spin and isospin dependence of the annihilation cross-section. In general, time-reversal and isospin invariance restricts the annihilation cross-section to depend on 6 independent energy-dependent terms. At large $N_c$, a spin-flavor symmetry emerges in the theory that acts to further restrict the dependence of the annihilation cross-section to three of these terms; the other terms amount to $1/N_c$ corrections. Assuming dominance of the leading order terms,…

Nucleon-antinucleon annihilation at LEAR

This report is a historical review of the salient results in low energy antiproton-proton and antineutron-proton annihilation obtained at the Low Energy Antiproton Ring (LEAR), which was operated at CERN between 1983 and 1996. The intention is to provide guidelines for future experiments at the CERN AD/ELENA complex and elsewhere. In the spirit of this workshop, hadron spectroscopy - one of the cornerstones at LEAR - is briefly mentioned, while emphasis is put on the annihilation mechanism on one and two nucleons, the final state multiplicity distributions and the contributions from quarks, in…

Antinucleon-nucleon interaction at next-to-next-to-next-to-leading order in chiral effective field theory

Results for the antinucleon-nucleon ($\bar NN$) interaction obtained at next-to-next-to-next-to-leading order in chiral effective field theory (EFT) are reported. A new local regularization scheme is used for the pion-exchange contributions that has been recently suggested and applied in a pertinent study of the $NN$ force within chiral EFT. Furthermore, an alternative strategy for estimating the uncertainty is utilized that no longer depends on a variation of the cutoffs. The low-energy constants associated with the arising contact terms are fixed by a fit to the phase shifts and inelasticiti…

Low-Energy Antinucleon-Nucleus Interaction Revisited

Annihilation cross sections of antiprotons and antineutrons on the proton between 50 and 400 MeV/c show Coulomb focusing below 200 MeV/c and almost no charge-dependence above 200 MeV/c. Similar comparisons for heavier targets are not possible for lack of overlap between nuclear targets studied with $\bar p$ and $\bar n$ beams. Interpolating between $\bar p$-nucleus annihilation cross sections with the help of an optical potential to compare with $\bar n$-nucleus annihilation cross sections reveal unexpected features of Coulomb interactions in the latter. Direct comparisons between $\bar n$-nuc…

A cornucopia of antineutrons and hyperons from super J/psi factory for next-generation nuclear and particle physics high-precision experiments

In order to study the interactions and structure of various types of matter one typically needs to carry out scattering experiments utilizing many different particles as projectiles. Whereas beams of $e^\pm$, $μ^\pm$, $π^\pm$, $K^\pm$, proton, antiproton, and of various heavy ions have been produced and have enabled many scientific breakthroughs, beams of antineutrons, hyperons ($Λ$, $Σ$ and $Ξ$) and their antiparticles are typically not easy to obtain. Here we point out and investigate a new high-quality source of these particles: a super $J/ψ$ factory with capability of accumulating trillion…

使用基于组分夸克模型的耦合道计算重新审视质子-反质子散射

Revisiting the proton-antiproton scattering using a constituent-quark-model based coupled-channels calculation

受重子偶素共振态分析进展启发，本文基于组分夸克模型对质子-反质子散射进行耦合道计算，发现核子-反核子动力学十分复杂，并在阈值附近富含散射奇点。

近阈值 $e^+e^-\ o N\ar{N}$ 截面的耦合道分析

Coupled-channel analysis of the near-threshold $e^+e^-\to N\bar{N}$ cross sections

本文在非相对论有效场论中纳入 $p\ar{p}$ 与 $n\ar{n}$ 耦合道、库仑作用及短程光学势，拟合 BESIII 和 SND 数据，揭示近阈值 $N\ar{N}$ 准束缚态与极点。