Related Experiment Video
Updated: Apr 25, 2026
06:53
Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
7.5K
Moments of the longitudinal proton structure function FL from global data in the Q(2) range 0.75-45.0 (GeV/c)(2)
P Monaghan1, A Accardi2, M E Christy1
1Hampton University, Hampton, Virginia 23668, USA.
Physical Review Letters
|August 29, 2014
Summary
Researchers extracted proton longitudinal structure function FL moments using new data. Leading twist models underestimate these moments, suggesting higher twist effects or larger gluon distributions at high x.
Area of Science:
- Nuclear Physics
- Particle Physics
- Quantum Chromodynamics
Background:
- The proton longitudinal structure function (FL) provides insights into nucleon structure.
- Understanding FL is crucial for testing Quantum Chromodynamics (QCD) predictions.
Purpose of the Study:
- To extract the lowest three moments of FL from a comprehensive world dataset.
- To determine these moments over a broad Q^2 range (0.75 to 45 GeV^2/c^2).
- To compare experimental results with theoretical predictions from leading twist parametrizations.
Main Methods:
- Compilation and analysis of global experimental data on FL.
- Extraction of FL moments at low and high Bjorken x.
- Utilizing new data from HERA and Jefferson Lab.
Main Results:
- The first determination of FL moments over an extended Q^2 range, minimizing extrapolation uncertainties.
- Experimental moments are found to be underestimated by leading twist structure function parametrizations.
- Discrepancies are more pronounced for higher moments.
Conclusions:
- The findings suggest the presence of significant higher twist effects in FL.
- Alternatively, a larger gluon distribution at high x may be indicated.
- These results challenge current leading twist descriptions of proton structure.
More Related Videos
09:49An Experimental Protocol for Femtosecond NIR/UV - XUV Pump-Probe Experiments with Free-Electron Lasers
Published on: October 23, 2018
15.9K
11:27Studying Soft-matter and Biological Systems over a Wide Length-scale from Nanometer and Micrometer Sizes at the Small-angle Neutron Diffractometer KWS-2
Published on: December 8, 2016
13.9K
Related Concept Videos
01:10Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
2.8K
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...
2.8K
01:07Proton (¹H) NMR: Chemical Shift
3.8K
Organic molecules primarily contain carbon and hydrogen atoms. While all the hydrogen isotopes are NMR-active, protium or hydrogen-1 is the most abundant. It has a significant energy separation between its nuclear spin states due to its large gyromagnetic ratio. As per Boltzmann's distribution, an increase in the energy separation implies a greater excess population of nuclei available for excitation, resulting in a strong NMR absorption signal.
Absorption signals of all the protium nuclei...
Absorption signals of all the protium nuclei...
3.8K
01:13¹H NMR: Complex Splitting
1.7K
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
1.7K
01:03Atomic Nuclei: Nuclear Spin State Overview
1.9K
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
1.9K
01:11Atomic Nuclei: Larmor Precession Frequency
3.5K
The earth's gravitational field produces a 'twisting force' perpendicular to the angular momentum of a spinning mass (such as a spinning top) that causes the mass to 'wobble' around the gravitational field axis in a phenomenon called precession. Similarly, the magnetic moment (μ) of a spinning nucleus precesses due to an external magnetic field directed along the z-axis. The precession of the magnetic moment vector about the magnetic field is called Larmor precession,...
3.5K
03:18Nuclear Stability
20.4K
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively...
To hold positively...
20.4K