| 词条 | Quantum chromodynamics binding energy |
| 释义 |
Source of MassMost of the mass of hadrons is actually QCD binding energy, through mass-energy equivalence. This phenomenon is related to chiral symmetry breaking. In the case of nucleons – protons and neutrons – QCD binding energy forms about 99% of the nucleon's mass. That is if assuming that the kinetic energy of the hadron's constituents, moving at near the speed of light, which contributes greatly to the hadron mass,[1] is part of QCD binding energy. For protons, the sum of the rest masses of the three valence quarks (two up quarks and one down quark) is approximately 9.4 MeV/c2, while the proton's total mass is about 938.3 MeV/c2. For neutrons, the sum of the rest masses of the three valence quarks (two down quarks and one up quark) is approximately 11.9 MeV/c2, while the neutron's total mass is about 939.6 MeV/c2. Considering that nearly all of the atom's mass is concentrated in the nucleons, this means that about 99% of the mass of everyday matter (baryonic matter) is, in fact, chromodynamic binding energy. Gluon EnergyWhile gluons are massless, they still possess energy – chromodynamic binding energy. In this way, they are similar to photons, which are also massless particles carrying energy – photon energy. The amount of energy per single gluon, or "gluon energy", cannot be calculated. Unlike photon energy, which is quantifiable, described by the Planck-Einstein relation and depends on a single variable (the photon's frequency), no formula exists for the quantity of energy carried by each gluon. While the effects of a single photon can be observed, single gluons have not been observed outside of a hadron. Due to the mathematical complexity of quantum chromodynamics and the somewhat chaotic structure of hadrons,[2] which are composed of gluons, valence quarks, sea quarks and other virtual particles, it is not even measurable how many gluons exist at a given moment inside a hadron. Additionally, not all of the QCD binding energy is gluon energy, but rather, some of it comes from the kinetic energy of the hadron's constituents. Therefore, only the total QCD binding energy per hadron can be stated. However, in the future, studies into quark-gluon plasma might be able to overcome this. See also
References1. ^1 {{cite web |url=http://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-structure-of-matter/protons-and-neutrons |title=Protons and Neutrons: The Massive Pandemonium in Matter |last1=Strassler |first1=Matt |last2= |first2= |date=15 April 2013 |website=Of Particular Significance |publisher= |access-date=30 May 2016 |quote=}} 2. ^{{cite web |url=http://www.sciencemag.org/news/2010/04/mass-common-quark-finally-nailed-down |title=Mass of the Common Quark Finally Nailed Down |last1=Cho |first1=Adrian |last2= |first2= |date=2 April 2010 |website=Science Magazine |publisher=AAAS |access-date=30 May 2016 |quote=}} 5 : Concepts in physics|Hadrons|Particle physics|Quantum chromodynamics|Binding energy |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。