The X17 particle, the E38 particle, and the anomalous soft photons are anomalous particles because they do not appear to belong to any known Standard Model families. We propose a QED meson description of the anomalous particles as composite systems of a light quark and a light antiquark bound and confined by the compact QED interaction, by combining Polyakov's transverse confinement of opposite electric charges in compact QED in (2+1)D and Schwinger's longitudinal confinement for massless opposite electric charges in QED in (1+1)D. With predicted QED meson masses close to the observed X17 and E38 masses, QED mesons may be good candidates for the description of the anomalous particles.
Schwinger's boson solution for massless fermions in QED in 1+1D has been applied and generalized to quarks interacting in QED and QCD interactions, leading to stable and confined open-string QED and QCD boson excitations of the quark-QCD-QED system in 1+1D. Just as the open-string QCD excitations in 1+1D can be the idealization of QCD mesons with a flux tube in 3+1D, so the open-string QED excitations in 1+1D may likewise be the idealization of QED mesons with masses in the tens of MeV region, corresponding possibly to the anomalous X17 and E38 particles observed recently. A further search for…
We discuss the generalization of the leading-twist light-cone distribution amplitude for light mesons including QED effects. This generalization was introduced to describe virtual collinear photon exchanges above the strong-interaction scale $Λ_{\rm QCD}$ in the factorization of QED effects in non-leptonic $B$-meson decays. In this paper we study the renormalization group evolution of this non-perturbative function. For charged mesons, in particular, this exhibits qualitative differences with respect to the well-known scale evolution in QCD only, especially regarding the endpoint-behaviour. We…
As a quark and an antiquark cannot be isolated, the intrinsic motion of a composite $q \bar q$ system in its lowest-energy states lies predominantly in 1+1 dimensions, as in an open string with the quark and the antiquark at its two ends. Accordingly, we study the lowest-energy states of an open string $q\bar q$ system in QCD and QED in 1+1 dimensions. We show that $π^0, η$, and $η'$ can be adequately described as open string $q\bar q$ QCD mesons. By extrapolating into the $q\bar q$ QED sector in which a quark and an antiquark interact with the QED interaction, we find an open string isoscalar…
We discuss the QED-generalized leading-twist light-cone distribution amplitudes of heavy mesons, that appear in QCD$\times$QED factorization theorems for exclusive two-body $B$ decays. In the presence of electrically charged particles, these functions should be more appropriately regarded as soft functions for heavy-meson decays into two back-to-back particles. In this paper, we derive the one-loop anomalous dimension of these soft functions and study their behaviour under renormalization-scale evolution, obtaining an exact solution in Laplace space. In addition, we provide numerical solutions…
Hadron masses are subject to few MeV corrections arising from QED interactions, almost entirely arising from the electric charge of the valence quarks. The QED effects include both self-energy contributions and interactions between the valence quarks/anti-quarks. By combining results from different signs of the valence quark electric charge we are able to isolate the interaction term which is dominated by the Coulomb piece, $\langle α_{\mathrm{QED}}e_{q_1}e_{\overline{q}_2}/r \rangle$, in the nonrelativistic limit. We study this for $D_s$, $η_c$ and $J/ψ$ mesons, working in lattice QCD plus qu…
We present a lattice analysis of the light pseudoscalar mesons with consideration for the mixing between the flavour-neutral states $π^0$, $η$ and $η^\prime$. We extract the masses and flavour compositions of the pseudoscalar meson nonet in $n_f=1+1+1$ lattice QCD+QED around an SU(3)-flavour symmetric point, and observe flavour-symmetry features of the extracted data, along with preliminary extrapolation results for the flavour compositions at the physical point. A key result of this work is the observed mass splitting between the $π^0$ and $η$ on our ensembles, which is found to exhibit behav…
This paper investigates how the nonzero temperature affects the differential cross-section for mesons scattering in a Lorentz-violating extension of the scalar electrodynamics. We initially discuss some features of the model and extract the zero temperature Feynman rules. Temperature effects are introduced using the Thermo Field Dynamics (TFD) formalism. It is shown that the corrections induced on the meson scattering are very large in the high-temperature regime. Furthermore, our results also suggest that temperature effects may contribute to new constraints on the Lorentz-violating parameter…
A symmetry-preserving treatment of mesons, within a Dyson-Schwinger and Bethe-Salpeter equations approach, demands an interconnection between the kernels of the quark gap equation and meson Bethe-Salpeter equation. Appealing to those symmetries expressed by the vector and axial-vector Ward-Green-Takahashi identitiges (WGTI), we construct a two-body Bethe-Salpeter kernel and study its implications in the vector channel; particularly, we analyze the structure of the quark-photon vertex, which explicitly develops a vector meson pole in the timelike axis and the quark anomlaous magnetic moment ter…
We investigate the in-medium modification of the charmonium breakup processes due to the Mott-effect for D-mesons at the chiral phase transition. A model calculation for the process J/Psi+pi --> D+D^*+ h.c. is presented which demonstrates that threshold effects in the thermal averaged breakup cross section can be explained as a Mott transition where final state quark-antiquark bound states enter the continuum of resonant states at the QCD phase transition. Applications to heavy-ion collisions within a modified Glauber model scenario and the phenomenon of anomalous J/$ψ$ suppression in the CERN…
Numerical calculation of high-order QED contributions to the electron anomalous magnetic moment
本文描述了一种数值计算高阶QED对电子反常磁矩贡献的方法。该方法是基于减法的红外和紫外发散费曼参数空间积分前和非自适应蒙特卡罗积分，成立于Hepp部门。文中介绍了该方法在图形加速器NVidia Tesla K80上的实现。提出了一种在不损失计算速度的情况下消除因数值相减发散而产生的舍入误差的方法。给出了将该方法应用于所有不含轻子圈的2圈、3圈、4圈QED Feynman图的结果。文中给出了两圈和三圈结果与已知解析结果的详细比较。给出了6个规范不变4-圈图类的贡献与已知解析值的比较。此外，78套4-回路图的贡献，与质量壳上的直接减法比较。此外，给出了5-回路和6-回路梯形图的贡献，并将这些结果与已知的解析结果进行了比较。文中详细描述了所产生的蒙特卡罗样本的行为，并给出了误差估计的方法。一个详细的信息，这些计算的图形处理器的性能和蒙特卡罗收敛的文件。
Beyond scalar QED radiative corrections: the $ρ^{\pm}-ρ^0$ width difference, FSR corrections and their impact on $Δa_μ^{\rm HVP, LO}[τ]$
Universidad Autónoma de Nuevo León（新莱昂自治大学）；Centro de Investigación y de Estudios Avanzados del IPN（墨西哥国立理工学院高级研究中心）；Universidad Nacional Autónoma de México（墨西哥国立自治大学）
Four-loop Anomalous Dimensions of Scalar-QED Theory from Operator Product Expansion
School of Physics and Technology, Nanjing Normal University（南京师范大学物理科学与技术学院）；Graduate School of China Academy of Engineering Physics（中国工程物理研究院研究生院）；School of Physics, Hubei University（湖北大学物理学院）
