相关实验视频
Updated: May 30, 2025

07:46
Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
8.5K
概括
CMS实验测量了来自质子对质子碰撞的喷气式喷气生产截面. 这些结果为部分分布函数和强合常数提供了精确的约束.
科学领域:
- 高能物理 高能物理
- 粒子物理学 粒子物理学
- 量子色态动力学 量子色态动力学
背景情况:
- 粒子物理学的标准模型描述了基本粒子和力.
- 大强子对撞机 (LHC) 的质子-质子碰撞提供了一个独特的环境来测试量子染色力学 (QCD).
- 喷射生产是QCD的一个基本过程,对质子的内部结构敏感.
研究的目的:
- 用于高精度测量喷气式生产截面.
- 提供可以限制部分分布函数 (PDF) 的数据.
- 要确定Z玻色子质量的强合常数 ($\alpha_s$).
主要方法:
- 利用了2016年LHCCMS实验收集的质子对质子碰撞数据.
- 使用anti-$k_T$算法重建喷气机,使用距离参数R=0.4$和R=0.8$.
- 执行双差分和三差分横截面测量,为探测器效应展开.
主要成果:
- 作为动力学变量的函数,呈现了喷气式横截面的精确测量.
- 在扰乱的QCD中,将展开的横截面与理论预测相比较,以次之先的顺序排列.
- 研究了这些测量对PDF文件的影响,并确定$\alpha_s(m_Z) = 0.114$.
结论:
- 这些测量提供了对扰动性QCD计算的严格测试.
- 结果在确定PDF文件方面提供了显著的改进.
- 获得了强连接常数的精确值,有助于理解强力.
相关概念视频
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
1.0K
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...
1.0K
Mass Analyzers: Common Types
550
The quadrupole mass analyzer consists of four cylindrical metal rods arranged in a diamond carrying a DC voltage and a radio-frequency AC voltage. The motion of ions through the quadrupole depends on the field strength, causing only ions of a certain m/z to resonate successfully and strike the detector at a given field strength. Though the transmission rate for these analyzers is high, the exact elemental composition of the sample is not determined because of low resolution; however, they are...
550
Tandem Mass Spectrometry
878
Tandem mass spectrometry is a technique that uses multiple mass analyzers in series to obtain a higher selectivity and signal-to-noise ratio for the analyte. Instruments with multiple analyzers separated by an interaction cell enable secondary fragmentation and selected study of the fragment ions.
Secondary fragmentations occur in the interaction cell and can be induced by various factors. Fragmentation induced by collision with inert gases, such as N2, Ar, He, etc., is called collision-induced...
Secondary fragmentations occur in the interaction cell and can be induced by various factors. Fragmentation induced by collision with inert gases, such as N2, Ar, He, etc., is called collision-induced...
878
Mass Analyzers: Overview
569
The mass analyzer is a crucial component of the mass spectrometer. In the ionization chamber, the vaporized sample is bombarded with a high-energy electron beam to generate a radical cation and further fragment into neutral molecules, radicals, and cations. A series of negatively charged accelerator plates accelerate the cations into the mass analyzer. The mass analyzer separates ions according to their mass-to-charge (m/z) ratios and then directs them to the detector. The common types of mass...
569
Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
1.1K
In the AX proton spin system, proton A can sense the two spin states of a coupled proton X, resulting in a doublet NMR signal with two peaks of equal (1:1) intensity. When proton A is coupled to two equivalent protons (AX2 spin system), the spin states of each X can be aligned with or against the external field, creating three possible scenarios. This results in a 1:2:1 triplet signal, where the central peak corresponds to the chemical shift of A and is twice as large or intense as the...
1.1K

