含氢体系中双光子过程的有限质量效应：有效标量光子相互作用

A note on the contribution of multi-photon processes to radiative opacity

Recently, Bailey et al. performed iron opacity measurements on the Z machine at Sandia National Laboratory in conditions close to the ones of the base of the convective zone of the Sun. Such experiments have raised questions about the physical models commonly used in opacity codes. To understand the discrepancy between experiment and theory, More et al. investigated the role of two-photon processes. In the present work we show, by a simple estimate and using hydrogenic formulas, that due to the intensity of the backlight radiation seen by the sample, such processes are likely to play an import…

Single-color two-photon spectroscopy of Rydberg states in electric fields

Rydberg states of atomic helium with principal quantum numbers ranging from n=20 to n=100 have been prepared by non-resonance-enhanced single-color two-photon excitation from the metastable 2 {^3}S{_1} state. Photoexcitation was carried out using linearly and circularly polarized pulsed laser radiation. In the case of excitation with circularly polarized radiation, Rydberg states with azimuthal quantum number |m_{\ell}|=2 were prepared in zero electric field, and in homogeneous electric fields oriented parallel to the propagation axis of the laser radiation. In sufficiently strong electric fie…

Relativistic two-photon decay rates with the Lagrange-mesh method

Relativistic two-photon decay rates of the $2s_{1/2}$ and $2p_{1/2}$ states towards the $1s_{1/2}$ ground state of hydrogenic atoms are calculated by using numerically exact energies and wave functions obtained from the Dirac equation with the Lagrange-mesh method. This approach is an approximate variational method taking the form of equations on a grid because of the use of a Gauss quadrature approximation. Highly accurate values are obtained by a simple calculation involving different meshes for the initial, final and intermediate wave functions and for the calculation of matrix elements. Th…

类氢原子双光子衰变宽度的自能修正

Self-Energy Correction to the Two-Photon Decay Width in Hydrogenlike Atoms

研究了类氢原子双光子衰变宽度的超前对数辐射修正的规范不变性。它示出，一个有效的治疗使用兰姆移位“潜在”的校正导致等效的结果，在长度以及速度计提供的所有相关的校正项被考虑在内。具体地说，相关的辐射修正与进入传播子的能量、哈密顿量、波函数以及两个光子之间的能量守恒条件有关;所有这些效应的形式在两个规范中是不同的，但最终的结果被证明是规范不变的，这是应该的。虽然实际的计算只涉及非相对论性类氢格林函数的积分，但导出主导对数修正可以被认为比其他典型的对数项稍微复杂一些。对2S双光子衰变宽度的主要辐射修正为-2.020536（alpha/pi）（Zalpha）^2 ln[（Zalpha）^-2]，单位为主导非相对论表达式。这一结果与长度规计算[S. G. Karshenboim和V.G. Ivanov，e-print physics/9702027]，其中系数被给出为-2.025（1）。

Quantum interference effects in laser spectroscopy of muonic hydrogen, deuterium, and helium-3

Quantum interference between energetically close states is theoretically investigated, with the state structure being observed via laser spectroscopy. In this work, we focus on hyperfine states of selected hydrogenic muonic isotopes, and on how quantum interference affects the measured Lamb shift. The process of photon excitation and subsequent photon decay is implemented within the framework of nonrelativistic second-order perturbation theory. Due to its experimental interest, calculations are performed for muonic hydrogen, deuterium, and helium-3. We restrict our analysis to the case of phot…

通过标量-光子耦合的圈修正对标量暗物质与光子以外粒子相互作用的限制

Limits on scalar dark matter interactions with particles other than the photon via loop corrections to the scalar-photon coupling

针对质量超$10^{-3}$ eV的标量暗物质与非光子粒子相互作用信息不足的问题，研究通过计算标量-光子耦合的单圈量子修正，结合相关实验结果得到多类相互作用的新限制，部分限制强度提升2至15个数量级且排除了标量粒子解释μ子g-2反常的可能。

含角动量依赖的类氢原子连续态-连续态跃迁振幅解析表达式

Analytical Expression for Continuum-continuum Transition Amplitude of Hydrogen-like Atoms with Angular-momentum Dependence

针对阿秒双光子跃迁中连续态-连续态跃迁项难以模拟的问题，提出基于Appell F1函数的解析表达式，显著提升了低动能和高角动量态下的准确度，并与含时薛定谔方程数值模拟定量吻合。

利用原子光谱约束变色龙-光子耦合

Constraining the chameleon-photon coupling with atomic spectroscopy

本文通过原子光谱计算变色龙场对原子能级的扰动，并纳入质子标量电荷效应，首次排除了跨越约四个数量级的变色龙-光子耦合参数空间。