Related Experiment Video
Updated: Apr 7, 2026
09:00
Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
Published on: June 28, 2018
10.7K
Observation of the ψ(1 3D2) State in e+e-→π+π-γχc1 at BESIII.
M Ablikim1, M N Achasov2, X C Ai1
1Institute of High Energy Physics, Beijing 100049, People's Republic of China.
Physical Review Letters
|July 17, 2015
Summary
Researchers observed the X(3823) particle in electron-positron collisions, measuring its mass and width. This finding supports its identification as the ψ(1 3D2) charmonium state.
Area of Science:
- Particle Physics
- Quantum Chromodynamics
- Hadron Spectroscopy
Background:
- Understanding the nature of charmonium states is crucial for testing quantum chromodynamics.
- The X(3823) is a candidate charmonium state whose properties require experimental verification.
Purpose of the Study:
- To observe and characterize the X(3823) particle.
- To determine the quantum numbers and properties of the X(3823) state.
- To investigate the decay modes of the X(3823) state.
Main Methods:
- Analysis of electron-positron collision data collected by the BESIII detector.
- Reconstruction of the π+π-γχc1 final state to identify the X(3823) signal.
- Measurement of the mass, width, cross sections, and branching ratios associated with the X(3823) state.
Main Results:
- Observation of the X(3823) state with a statistical significance of 6.2σ.
- Measured mass of the X(3823) state: (3821.7±1.3±0.7) MeV/c², with width < 16 MeV at 90% confidence level.
- Measurements of Born cross sections and branching ratios are consistent with the ψ(1 3D2) assignment.
Conclusions:
- The experimental results strongly support the assignment of the X(3823) as the ψ(1 3D2) charmonium state.
- This observation contributes to the detailed understanding of the charmonium spectrum.
Related Concept Videos
01:21Chemical Ionization (CI) Mass Spectrometry
1.7K
The molecular ion peak of a molecule in the mass spectrum provides vital information for molecular identification. However, conventional electron impact ionization can lead to the rapid dissociation of some molecular ions before they reach the detector. A milder ionization method is required to increase the lifetime of such ionized analyte molecules. Chemical ionization (CI) is a gas-phase protonation reaction useful for mass-analyzing analyte molecules that are easily protonated to yield the...
1.7K
01:04¹³C NMR: ¹H–¹³C Decoupling
2.1K
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
2.1K
01:24π Molecular Orbitals of 1,3-Butadiene
12.7K
Conjugated dienes have lower heats of hydrogenation than cumulated and isolated dienes, making them more stable. The enhanced stabilization of conjugated systems can be understood from their π molecular orbitals.
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...
12.7K
01:15Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)
1.2K
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) is an advanced Nuclear Magnetic Resonance (NMR) technique specifically designed to detect and enhance the signals of low-abundance nuclei, such as carbon-13 and nitrogen-15, in small molecules. The fundamental principle behind INEPT is the transfer of polarization from a more abundant and highly polarizable nucleus, typically hydrogen-1, to the low-abundance nucleus of interest. This process effectively boosts the NMR signal of the...
1.2K
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
1.9K
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...
1.9K
01:10Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
3.2K
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...
3.2K