相关实验视频

Updated: Jul 16, 2025

Setting Limits on Supersymmetry Using Simplified Models

Setting Limits on Supersymmetry Using Simplified Models

Published on: November 15, 2013

在天文距离上的奇特自旋依赖相互作用的新极限

L Y Wu¹, K Y Zhang¹, M Peng¹

¹Key Laboratory of Neutron Physics, Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900, Sichuan, China and Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900, Sichuan, China.

Physical review letters

|September 18, 2023

概括

新的研究为异国情调的自旋依赖相互作用设定了最严格的实验限制. 通过分析现有数据,科学家们已经限制了超越标准模型的新光粒子和基本物理.

科学领域:

现代物理学的现代物理学
粒子物理学的粒子物理学.
天体物理学天体物理学

背景情况:

涉及新光粒子的奇特的自旋依赖相互作用对于解决物理学的基本问题至关重要.
这些相互作用可以在极化中子和非极化核子之间以各种形式表现出来.
太阳和月亮等潜在的天体物理来源可能会在实验室环境中引发可检测的变化.

研究的目的:

为了在天文范围获得异国情调的自旋依赖相互作用的新的实验上限.
改善对特定相互作用类型的约束,包括标量-伪标量,向量-轴向量和轴向-轴向量.
将分析扩展到哈里·达斯的相互作用,并建立新的约束.

主要方法:

对洛伦茨和CPT违规的实验室测量现有数据的分析.
利用天文观测来探测自旋依赖相互作用.
应用理论框架来推导实验上限.

主要成果:

建立了迄今为止对g_{S}^{N}g_{P}^{n}相互作用最严格的实验上限,超过了之前的联合天体物理-实验室极限.
报告了天文尺度上的矢量-轴向量和轴向-轴向量相互作用的新约束,矢量-轴向量极限显著改善.
对哈里·达斯的相互作用产生了新的约束.

结论:

这项研究提供了迄今为止对异国情调的自旋依赖相互作用最严格的实验约束.
这些发现有助于寻找超越标准模型的新物理.
这项研究推动了我们对基本相互作用及其天体物理含义的理解.

更多相关视频

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser

Published on: June 28, 2018

High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

Published on: October 10, 2014

相关概念视频

Spin–Spin Coupling Constant: Overview

Spin–Spin Coupling Constant: Overview

In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...

NMR Spectroscopy: Spin–Spin Coupling

NMR Spectroscopy: Spin–Spin Coupling

The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved...

¹H NMR: Interpreting Distorted and Overlapping Signals

¹H NMR: Interpreting Distorted and Overlapping Signals

Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...

Atomic Nuclei: Nuclear Spin State Population Distribution

Atomic Nuclei: Nuclear Spin State Population Distribution

Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.

Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)

Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)

Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...

Spin–Spin Coupling: One-Bond Coupling

Spin–Spin Coupling: One-Bond Coupling

Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...