Neutrino magnetic moment, millicharge and charge radius
Konstantin A. Kouzakov, Alexander I. Studenikin
本文从理论的角度对中微子的电磁性质作了简要的概述。概述了它们对中微子-核相干弹性散射的潜在影响。
A brief overview of neutrino electromagnetic properties is presented from a theoretical perspective. Their potential effects on coherent elastic neutrino-nucleus scattering are outlined.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
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We consider possible effects of neutrino electric charge (millicharge) and charge radius on the neutrino-atom interaction processes such as (i) atomic ionization by neutrino impact and (ii) coherent elastic neutrino-nucleus scattering. The bounds on the neutrino millicharge and charge radius that follow from, respectively, the GEMMA and COHERENT experiments are presented and discussed.
New bounds on neutrino electric millicharge from GEMMA experiment on neutrino magnetic moment
利用GEMMA实验最近得到的中微子反常磁矩的新极限，通过比较中微子磁矩和毫荷对实验电子反冲能阈下总截面的贡献，得到了中微子电毫荷$\mid q_ν \mid \sim 1.5 \times 10^{-12} e_0$（$e_0$是电子电荷的绝对值）可能的新的直接上界的数量级估计.这一估计证实了GEMMA数据使用已建立的统计程序和中微子毫荷绝对值$\mid q_ν \mid < 2.7 \times 10^{-12} e_0 \ (90\% CL)$上的一个新的直接绑定进行分析。该限值比之前从TEXONO反应堆实验数据中获得的限值更为严格，该数据已纳入2012年粒子特性综述。
New bounds on neutrino electric millicharge from limits on neutrino magnetic moment
利用最近在反应堆反中微子与自由电子散射截面测量的GEMMA实验中得到的中微子反常磁矩的新极限，我们得到了中微子毫荷$\mid q_ν \mid < 1.5 \times 10^{-12} e_0$的一个新的直接上界.这是比先前从TEXONO反应堆实验数据中获得的约束严格2倍的约束，该约束包括在2012年粒子特性综述中。我们预测，从正在进行的新阶段的GEMMA实验的数据上的中微子毫荷的上限将减少到$\mid q_ν \mid < 3.7 \times 10^{-13}e_0$在两年内。我们还预测，在下一阶段的实验中，毫电荷的上限将比目前的上限减少一个数量级，并在大约四年内达到$\mid q_ν \mid < 1.8 \times 10^{-13}e_0$的水平。
Elastic neutrino-atom scattering as a probe of neutrino millicharge and magnetic moment
本文研究了低能转移下的相干弹性中微子-原子散射，针对H、$^2$H、$^3$He和$^4$He等目标进行理论计算，揭示了中微子毫电荷与磁矩在原子反冲谱中的体现，为相关实验（如超流He-4）规划提供理论依据。
Millicharged neutrino with anomalous magnetic moment in rotating magnetized matter
在极端背景条件下，得到了描述具有非平凡电磁性质的中微子的修正狄拉克方程的新的精确解。在准经典处理中，引入了描述中微子在磁化旋转物质中传播的有效洛伦兹力。我们预测了不同类型的相对论中微子和反中微子（不同的口味和能量）的空间分离的磁化旋转物质的恒星的效果。低能量的中微子甚至可以被困在恒星内部。我们还预言了两种新现象：一种新的中微子电磁辐射（称为“（milli）带电中微子光”，$LCν$）和一种新的中微子逃逸恒星角速度漂移机制（称为“中微子转星”机制，$νS T$）。$νS T$机制对超新星爆发的可能影响产生了中微子毫电荷$q_ν<1.3\times10^{-19}e_0$的新的天体物理极限。此外，$νS T$机制也可以用来解释脉冲星“反毛刺”和普通毛刺的起源。
Search for millicharged particles in reactor neutrino experiments: a probe of the PVLAS anomaly
最近有人提出，PVLAS实验所观察到的真空磁二向色性可以用一种新的光（m ~0.1 eV，毫荷电，q ~ 3 10^{-6} e）费米子的成对产生来解释。此外，有人指出，q > 10^{-9} e的毫荷电粒子自然出现在基于弦论的模型中。我们表明，低能反应堆中微子实验提供了一个敏感的探针毫荷电粒子。以TEXONO实验寻找中微子磁矩的最新结果为例，导出了质量区m < 1 keV时q < 10^{-5} e的新上限.这些结果增强了在不久的将来的实验中更灵敏地搜索这种粒子的动机。此外，还得到了电子反中微子的电荷q < 3.7 × 10 - 12} e的直接实验极限。
Elastic neutrino-electron scattering represents a powerful tool to investigate key neutrino properties. In view of the recent results released by the LUX-ZEPLIN collaboration, we provide a first determination of the limits achievable on the neutrino magnetic moment and neutrino millicharge, whose effect becomes non-negligible in some beyond the Standard Model theories. In this context, we evaluate and discuss the impact of different approximations to describe the neutrino interaction with atomic electrons. The new LUX-ZEPLIN data allows us to set a very competitive limit on the neutrino magnet…
We perform a constrained spectral fit analysis of the excess observed in the electron recoil energy spectrum by XENON1T with neutrino magnetic moment, charge radius, neutrino millicharge and new light vector and scalar mediators. Within the limits allowed by other laboratory experiments we find that the excess can be explained in the range$\ (2-4)\times 10^{-11}μ_{B} $ for the magnetic moment,$\ (2-6)\times 10^{-31}$cm$^{2}$ for the charge radius, $\ (1.7-2.3)\times 10^{-12}e$ for the millicharge and $(10-100)\ $keV masses of light mediators with couplings of $ 3.5\times 10^{-7}$ for vector/ax…
We derive new limits on the neutrino electromagnetic interactions and weakly coupled light vector and scalar mediators using the recent XENONnT data of the solar neutrino-electron elastic scattering. XENONnT has already reported the world's best constraint on the flavor-independent effective neutrino magnetic moment with almost twice the exposure and improved systematics. We extend this analysis and derive constraints on all the possible electromagnetic interactions and flavor universal light gauge boson couplings and masses, which could contribute to the neutrino-electron elastic scattering p…
Neutrino Electromagnetic Properties and the Weak Mixing Angle at the LHC Forward Physics Facility
本文研究LHC前向物理设施（FPF）探测中微子电磁性质的能力，发现其可对陶中微子磁矩和毫电荷给出比DONUT更强的限制，并通过中性流深度非弹性散射精确测量电荷半径及弱混合角，有望以约3%精度在Q约10 GeV处测量sin²θ_W，为NuTeV反常提供新线索。
Electromagnetic neutrino: a short review
本文对中微子电磁性质的若干问题作了简要的评述。在简要回顾了中微子电磁形状因子的理论基础之后，讨论了来自地面实验和天体物理观测的中微子磁矩和电毫荷的约束。我们还关注一些最近的研究问题和前景。
Testing neutrino electromagnetic properties at current and future dark matter experiments
本研究利用PandaX-4T、LUX-ZEPLIN、XENONnT三个暗物质直接探测实验数据，采用更保守的本底不确定性处理方法约束中微子电磁性质，同时指出未来DARWIN装置可提升约束精度，甚至有望首次测量符合标准模型预测的电子中微子电荷半径。
We report first constraints on neutrino electromagnetic properties from neutrino-electron scattering using data obtained from the CONUS germanium detectors, i.e. an upper limit on the effective neutrino magnetic moment and an upper limit on the effective neutrino millicharge. The electron antineutrinos are emitted from the 3.9 GW$_\mathrm{th}$ reactor core of the Brokdorf nuclear power plant in Germany. The CONUS low background detectors are positioned at 17.1 m distance from the reactor core center. The analyzed data set includes 689.1 kg$\cdot$d collected during reactor ON periods and 131.0 …
Constraining neutrino electromagnetic properties by germanium detectors
中微子的电磁性质在标准模型中要么微不足道，要么可以忽略不计，但它可以探索新的物理学，并在天体物理学和宇宙学中具有重要意义。目前最好的直接限制中微子毫电荷和磁矩都来自与锗探测器在千电子伏水平的低阈值的数据。在本文中，我们详细讨论了一个强大的，从头算方法：多组态相对论无规相位近似，使我们能够可靠地了解锗探测器的响应在亚千电子伏的水平，原子多体物理问题。使用现有的数据与子千电子伏的阈值，限制反应堆反中微子的毫电荷，磁矩，和电荷半径平方。下一代实验的预计灵敏度也给出和讨论。
After a brief reminder on the electromagnetic properties of neutrinos, the main processes of the electromagnetic interactions of neutrinos in astrophysics and the corresponding limitations on millicharges and effective magnetic moments of the particle are discussed.
Celestial probes of dark matter electromagnetic interactions
该研究通过分析天体的中微子通量与加热效应，推导暗物质电磁矩的约束，发现天体可在直接搜寻失效区域提供领先约束，揭示天体俘获与其他暗物质搜寻的互补性。
After a brief introduction to neutrino electromagnetic properties we focus on the most important constraints on neutrino magnetic moments, charge radii and millicharges from the terrestrial experiments and astrophysical considerations. The promising new possibilities for constraining neutrino electromagnetic properties in future experiments are also discussed.
Electron energy and angular distributions in the process of low-energy elastic neutrino-electron scattering are treated in the free-electron approximation. The effects of the millicharges, magnetic, electric, and anapole moments of massive neutrinos along with the flavor change of neutrinos traveling from the source to the detector are taken into account under the assumption of three-neutrino mixing. The footprints of neutrino electromagnetic interactions in the electron energy and angle distributions are discussed.
We derive an effective neutrino evolution Hamiltonian and corresponding expression for neutrino spin oscillations probabilities accounting for neutrino interactions with external electric current due to neutrino charge radii and anapole moment. The results are interesting for possible applications in astrophysics.
Neutrino Electromagnetic Properties
本文系统回顾了中微子电磁性质的理论框架、实验限制及其在天体物理和惰性中微子磁矩门户中的现象学意义。
The electromagnetic properties of neutrinos have attracted considerable attention from researchers for many decades (see [1] for a review). However, until recently, there was no indication in favour of nonzero electromagnetic properties of neutrinos either from laboratory experiments with ground-based neutrino sources or from observations of astrophysical neutrino fluxes. The situation changed after the XENON collaboration reported [2] results of the search for new physics with low-energy electronic recoil data recorded with the XENON1T detector. The results show an excess of events over the k…
Bounds on tau neutrino magnetic moment and charge radius from Super-K and SNO observations
除了带电和中性电流通道外，中微子还可以通过它们的磁矩和电荷半径散射水探测器中的电子。SNO最近公布的太阳中微子带电电流事件率与Super-Kamiokande早期的太阳和大气中微子观测结果使我们能够将$μ<10^{-9} μ_B$的上界放在中微子磁矩上，将$<r^2> < 10^{-31} cm^2$放在中微子电荷半径上。对于电子和μ介子中微子，这些界限与现有的界限相当，但对于τ中微子，这些界限比早期的地球界限严格三个数量级。这些界限与任何特定的中微子振荡模型无关。
We show that a proposal which involves an effective radius derived from an effective potential that includes a linear extra-potential may solve both the proton and deuteron size puzzle. Moreover, this solution preserves the e-μ universality and helps to solve the anomalous magnetic moment of the muon too. Still, it is consistent with the rms magnetic radius of the proton and deuteron, the rms charge radius of both the ordinary and muonic C12 as well as the kaonic and pionic X-rays spectroscopy.
The milliQan Collaboration has proposed to search for millicharged particles by looking for very weakly ionizing tracks in a detector installed in a cavern near the CMS experiment at the LHC. We note that another form of exotica can also yield weakly ionizing tracks. If a heavy neutrino has an electric dipole moment (EDM), then the milliQan experiment may be sensitive to it as well. In particular, writing the general dimension-5 operator for an EDM with a scale of a TeV and a one-loop factor, one finds a potential EDM as high as a few times $10^{-17}$ e-cm, and models exist where it is an orde…
Wavefunction-Independent Relations between the Nucleon Axial-Coupling g_A and the Nucleon Magnetic Moments
我们利用光锥上的相对论三夸克模型计算了质子的磁矩$μ_p$和轴矢耦合$g_A$随其狄拉克半径$R_1$的变化。发现$μ_p$和$g_A$之间的关系与光锥波函数的假定形式无关。在物理半径$R_1=0.76$ fm处，我们得到了$μ_p$和$g_A$的实验值，并且价态$u$和$d$夸克携带的螺旋度相对于它们的非相对论性值都减小了$\simeq 0.75$。在大质子半径下，$μ_p$和$g_A$由通常的非相对论公式给出。在小半径处，$μ_p$变得等于狄拉克矩，如Drell-Hearn-Gerasimov求和规则所要求的。此外，当$R_1 \to 0,$时，组分夸克螺旋度变得完全无方向，并形成$g_A \to 0$。
We consider the effects of bound atomic electrons scattered by solar neutrinos due to the electromagnetic properties of neutrinos. This necessiate considering the recoil of atomic nucleus, which should be considered in the momentum conservation, but that effect to the energy conservation is negligible. This effect changes the kinematic behavior of the scattered electron compared to that scattered on free electrons. We apply this effect to the recent XENON1T data, but the bounds obtained from this is not very restrictive. We obtained the bounds: the (transition) magnetic moment $|f_{αβ}|\le 0.8…
Remarks on the proton charge radius
质子电荷半径由色散关系参数化的质子电磁形状因子计算。计算的电荷半径比用$μ$介子兰姆位移得到的电荷半径稍大。由于计算结果对小动量转移时质子电形状因子的实验数据敏感，因此核子形状因子的计算结果与Pohl等人的结果是否有出入，需要更精确的数据才能作出结论。
On Some Recent Ideas on the Proton Radius Puzzle and Lepton Anomalous Magnetic Moments
我们讨论了最近在[1，2]中提出的关于解决质子半径难题的建议以及在[3，4]中发现的$(α/π)^5$阶对轻子异常磁矩的非微扰量子电动力学贡献。我们证明了[1，2]的思想不能解决质子半径之谜。我们解释了文[3，4]中计算的非微扰修正不存在的原因。
Constraining neutrino electromagnetic properties with recent low-energy electron recoil data at dark matter direct detection experiments
利用 PandaX-4T 和 XENONnT 实验的低能电子 recoil 数据，研究中微子电磁性质的新约束。
The stellar energy loss rates due to the production of the neutrino pair process $e^+e^- \rightarrow (W, Z, γ) \rightarrow ν_e \bar{ν_e}$ are calculated in the minimal extension of Standard Model with electromagnetic properties of Dirac neutrinos which takes the account of the contribution of the neutrino charge radius, anapole moment and dipole moments. We have shown that the contribution of the electron neutrino's dipole moment is small compared with that of the charge radius. The obtained results are also considered with results obtained using the Standard Model.
We argue that the proton's charge-radius contributes differently to shifts of Hydrogen-like energy levels than naively expected due to an incorrect choice for the boundary condition at the proton's position in standard calculations. In particular we show how to obtain the correct boundary condition, which depends on the charge radius itself in a predictable way. We argue this difference in boundary conditions only matters when they are imposed at a radius $r=ε< Z α/m$ where $m$ is the orbiting-particle mass, because only then is the particle relativistic at these distances. The boundary condit…
We present a dispersion theoretical analysis of the experimental data on the electromagnetic form factors of the nucleon covering both the space- and time-like regions. The nucleon form factors over the full range of momentum transfers and the nucleon radius are extracted with high precision. The statistical uncertainties of the extracted form factors and radius are estimated using the bootstrap method, while systematic errors are determined from variations of the spectral functions. For the proton charge radius, we find $r_E^p = 0.840^{+0.003}_{-0.002}{}^{+0.002}_{-0.002}$~fm, in line with pr…
Recently, evidence for the observation of about 2 keV and below nuclear recoils from the coherent scattering of reactor anti-neutrinos off the germanium nuclei has been reported. We analyze the observed data to estimate the value of the weak mixing angle and constrain the neutrino millicharge, magnetic moment, charge radius and anapole moment contributing to the coherent scattering process. Currently, there is no definite model available for the quenching factor at such low energies. To this end, we consider various models of the quenching factor and show how it affects the interpretation of t…
The Strangeness Radius and Magnetic Moment of the Nucleon Revisited
我们更新了Jaffe对核子奇异等熵半径和磁矩的估计。我们利用最近的色散-理论拟合的核子电磁形状因子和一个改进的描述对称性破缺的矢量九重。我们发现$μ_s = -0.24 \pm 0.03$ ~ n. m。和$r_s^2 = 0.21 \pm 0.03$ ~fm $^2$。奇怪的形状因子$F_2^s (t)$遵循截止质量为1.46 GeV的偶极子$F_2^s (t)= μ_s (1-t/2.14 \, {\rm GeV}^2 )^{-2}$。这些数字应该被认为是奇异矢量流矩阵的上限-核子中的元素。
Determination of the moments of the proton charge density: is there a proton radius puzzle?
针对光谱学与散射实验给出的质子半径不一致问题，本文提出从动量空间密度测定任意大于-3阶空间矩的新方法，并用于质子电形状因子数据的全局分析。
We report a comprehensive analysis of the light and strange disconnected-sea quarks contribution to the nucleon magnetic moment, charge radius, and the electric and magnetic form factors. The lattice QCD calculation includes ensembles across several lattice volumes and lattice spacings with one of the ensembles at the physical pion mass. We adopt a model-independent extrapolation of the nucleon magnetic moment and the charge radius. We have performed a simultaneous chiral, infinite volume, and continuum extrapolation in a global fit to calculate results in the continuum limit. We find that the…
Momentum dependent flavor radiative corrections to the coherent elastic neutrino-nucleus scattering for the neutrino charge-radius determination
本文研究了CE$ν$NS中考虑中微子电荷半径时非零动量转移效应的辐射修正，重新分析实验数据表明该修正虽小但不可忽略，有助于提高电荷半径测定精度。
We briefly discuss the current status of lattice QCD simulations and review selective results on nucleon observables focusing on recent developments in the lattice QCD evaluation of the nucleon form factors and radii, parton distribution functions and their moments, and the neutron electric dipole moment. Nucleon charges and moments of parton distribution functions are presented using simulations generated at physical values of the quark masses, while exploratory studies are performed for the parton distribution functions and the neutron electric dipole moment at heavier than physical value of…
On Calculation of the Neutron Charge Radius
我们指出，夸克的反常磁矩和核子波函数中的相对论效应导致中子电荷半径的正确值。
RELATIVISTIC CORRECTIONS TO THE ELECTROMAGNETIC AND AXIAL MOMENTS OF NUCLEI AND OTHER COMPOSITE SYSTEMS
我们利用相对论性的双核子和三核子模型，在光锥上计算了氘核和Triton的电磁核矩和轴向核矩随半径的变化。结果还提供了一个估计的核约束修正螺旋度相关的深度非弹性散射求和规则。在较大的核子半径下，动量由通常的非相对论公式给出，并经有限束缚效应修正。在小半径处，矩采用由Drell-Hearn-Gerasimov求和规则的推广给出的正则值。此外，当R->0时，组分螺旋度变得完全无序，并且伽莫夫-泰勒矩阵元素消失。因此，在点状极限MR-->0时，自旋为1的束缚态的矩与标准模型中基本自旋为1的玻色子的正则耦合一致，mu=e/M，Q=-e/M^2，g_A=0。
Proton electron elastic scattering and the proton charge radius
有人建议，质子弹性散射原子电子允许质子电荷半径的精确测量。很小的转移动量值（比目前可用的小四个数量级）可以以很高的概率达到。
Moments of the neutron charge form factor and the N->Delta quadrupole transition
最近的数据允许一个新的参数化的中子电荷形状因子G_En。利用G_En与N->Delta四极子形状因子之间的无参数夸克模型关系，从G_En数据预测了N->Delta四极子形状因子。特别地，中子电荷半径与N->Delta四极矩有关，而G_En的四阶矩与N->Delta四极跃迁半径有关。从后者，我们得到一个实验值的轻组分夸克的电荷半径。最后，从弹性中子形状因子数据预测了π介子电生中的C2/M1比。
Implications of first LZ and XENONnT results: A comparative study of neutrino properties and light mediators
本研究利用LZ和XENONnT最新数据，比较分析中微子电磁性质和轻介子模型，发现XENONnT对磁矩和毫电荷的约束最强，且优于现有实验约一个数量级。
The proton charge-radius determinations from the electromagnetic form-factor measurements in electron-proton scattering require an extrapolation to zero momentum transfer ($Q^2=0$) which is prone to model-dependent assumptions. We show that the data at finite momentum transfer can be used to establish a rigorous lower bound on the proton charge radius. Using the available $ep$ data at low $Q^2$, we obtain $R_E > 0.850(1)$ fm as the lower bound on the proton radius. This reaffirms the discrepancy between the $ep$ and muonic-hydrogen values, while bypassing the model-dependent assumptions that g…
Background: There is significant current interest in knowing the value of the proton radius and also its proper definition. Purpose: Combine the disparate literatures of hydrogen spectroscopy and diverse modern parton distributions to show that the quantity $r_p^2\equiv -6 G_E'(0)$ is the relativistically proper definition that originates from the separate bodies of work. Methods: Use perturbation theory, light-front dynamics and elementary techniques to find relativistically correct definitions of the proton radius and charge density. Results: It is found that the very same proton radius is a…
The pion charge radius from charged pion electroproduction
我们分析了一个低能量的阈值π介子电产生定理，它允许一个确定的π介子的电荷半径。我们表明，在相同的顺序出现的半径，π介子环引起的纵向偶极子振幅$L_{0+}^{(-)}$的动量依赖性的修正。这种与模型无关的修正相当于从电生数据中得到的π电荷半径平方增加了约0.26 fm $^2$。它揭示了最近确定的π介子半径从电生产数据和一个基于π-电子散射之间的明显差异。
Relations of meson and nucleon electromagnetic and gravitational radii with quarks and gluons contributions
本文利用不同合作组的部分子分布函数计算了核子电磁和引力形状因子，发现核子的胶子引力半径与质子电磁半径相当，而夸克引力半径较小，且大动量转移下胶子引力形状因子下降更快。
Effects of neutrino charge radius and magnetic moment constraints obtained from the astrophysical observations and reactor experiments, as well as in-medium modifications of the weak and electromagnetic nucleon form factors of the matter on the neutrino electroweak interaction with dense matter, are estimated. We use a relativistic mean-field model for the in-medium effective nucleon mass and quark-meson coupling model for nucleon form factors. We analyze the neutrino scattering cross section and mean free path in cold nuclear matter. We find that the increase of the cross section relative to …
We report a lattice QCD calculation of the strange quark contribution to the nucleon's magnetic moment and charge radius. This analysis presents the first direct determination of strange electromagnetic form factors including at the physical pion mass. We perform a model-independent extraction of the strange magnetic moment and the strange charge radius from the electromagnetic form factors in the momentum transfer range of $0.051 \,\text{GeV}^2 \lesssim Q^2 \lesssim 1.31 \,\text{GeV}^2 $. The finite lattice spacing and finite volume corrections are included in a global fit with $24$ valence q…
Coherent elastic neutrino-nucleus scattering (CE$ν$NS) represents a powerful tool to investigate key electroweak physics parameters and neutrino properties since its first observation in 2017 by the COHERENT experiment exploiting the spallation neutron source at Oak Ridge National Laboratory. In light of the recent detection of such a process with antineutrinos produced by the Dresden-II reactor scattering off a germanium detector, we revisit the limits so far set on the neutrino magnetic moments, charge radii and millicharges as well as on the weak mixing angle. In order to do so, we also inc…
Lattice QCD calculations of nucleon form factors are restricted to discrete values of the Euclidean four-momentum transfer. Therefore, the extraction of radii typically relies on parametrizing and fitting the lattice QCD data to obtain its slope close to zero momentum transfer. We investigate a new method, which allows to compute the nucleon radius directly from existing lattice QCD data, without assuming a functional form for the momentum dependence of the underlying form factor. The method is illustrated for the case of the isovector mean square charge radius of the nucleon $\langle r^2_\mat…
Interaction of Dirac and Majorana Neutrinos with Weak Gravitational Fields
本文简要地讨论了高能中微子与弱引力场的相互作用。从洛伦兹不变性和规范不变性出发，推导了引力子-中微子顶点的形状，得到了中微子引力形状因子的非相对论解释。我们评论重整化条件，弱等效原理的保存和中微子质量半径的定义。我们将中微子引力形状因子与特定的角动量态联系起来。基于费曼图、自旋统计、CP不变性和中微子-引力子顶点角动量态的对称性，我们推导了Majorana和Dirac情形的不同之处。然后证明，尽管这两种情况之间的理论差异，只要考虑到实验，他们将几乎无法区分任何时空几何满足弱场条件。然后，我们计算的过渡引力形状因子的中微子通过评估相关的费曼图在1圈和估计中微子过渡质量半径。可以看出，形状因子对动量传递的依赖非常弱。中微子跃迁质量半径比典型的中微子电荷半径小几个数量级。
Breakdown of the expansion of finite-size corrections to the hydrogen Lamb shift in moments of charge distribution
我们量化的有限尺寸效应，其中领先的$[(Zα)^4]$和subleading $[(Zα)^5]$的兰姆位移的贡献是由均方半径和第三Zemach时刻的电荷分布的通常会计的限制。当核形状因子在与玻尔半径的倒数相当的尺度上存在任何非光滑行为时，兰姆位移在矩中的扩展就失效了。这与“质子大小之谜”的一些解释有关。例如，我们发现，尽管第三泽马赫矩的值很大，但关于质子形状因子的德·鲁尤拉玩具模型并没有像声称的那样解决这个难题。在不依赖于半径膨胀的情况下，我们展示了在MeV尺度下质子电形状因子的微小百分之一（pcm）变化将能够解释这个难题。它表明，一个需要知道所有的软贡献质子电形状因子PCM精度的精确提取的质子电荷半径从原子兰姆位移。
We use a method to calculate the hadron's charge radius without model-dependent momentum extrapolations. The method does not require the additional quark propagator inversions on the twisted boundary conditions or the computation of the momentum derivatives of quark propagators and thus is easy to implement. We apply this method to the calculation of pion charge radius $\langle r_π^2\rangle$. For comparison, we also determine $\langle r_π^2\rangle$ with the traditional approach of computing the slope of the form factors. The new method produces results consistent with those from the traditiona…
In a recent paper, Hagelstein and Pascalutsa examine the error associated with an expansion of proton structure corrections to the Lamb shift in terms of moments of the charge distribution. They propose a small modification to a conventional parameterization of the proton's charge form factor and show that this can resolve the proton radius puzzle. However, while the size of the "bump" they add to the form factor is small, it is large compared to the total proton structure effects in the initial parameterization, yielding a final form factor that is unphysical. Reducing their modification to t…
Energy Dependence of the Breit-Wheeler process in Heavy-Ion Collisions and its Application to Nuclear Charge Radius Measurements
本研究计算重离子碰撞中布赖特-惠勒过程截面与双电子横动量分布的能量依赖性，阐明其与核电荷分布的关联，提出该过程的适用判据，证实可利用其实验测量定量约束核电荷半径。
Proton charge radius extraction from muon scattering at MUSE using dispersively improved chiral effective field theory
本研究基于 DIχEFT 框架分析 MUSE 低能 μp 弹性散射，确定提取质子电荷半径的最佳运动学、理论不确定性与双光子交换修正，并给出 μp/ep 截面预测。
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