Proton-to-electron mass ratio
- Proton-to-electron mass ratio
The proton-to-electron mass ratio, , is given simply by the proton mass divided by the electron mass. It is considered a fundamental quantity in physics, as it is dimensionless in all systems of units. It has a numerical value given by 1836.1526724718(80) (i.e. there is a 1 standard deviation uncertainty in the last two digits of ±80).
It turns out that the mass of the proton is composed primarily of gluons, and not of the individual quark masses (the up quark and down quark). In fact, in the chiral limit, the mass of the proton, , is proportional to the QCD energy scale, . At a given energy scale, the strong coupling constant is related to the QCD scale (and thus ) as
:
where . is the number of quark flavours.
References
* http://physics.nist.gov/cgi-bin/cuu/Value?mpsme (Current CODATA recommended value)
ee also
* proton
* quark
* electron
* QCD
* Coupling constant
Wikimedia Foundation.
2010.
Look at other dictionaries:
Electron — For other uses, see Electron (disambiguation). Electron Experiments with a Crookes tube first demonstrated the particle nature of electrons. In this illustration, the profile of the cross shaped target is projected against the tube face at right… … Wikipedia
Électron — Traduction à relire Electron → … Wikipédia en Français
Mass spectrometry — (MS) is an analytical technique that measures the mass to charge ratio of charged particles.[1] It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical… … Wikipedia
Proton — For other uses, see Proton (disambiguation). This article is about the proton as a subatomic particle. For the aqueous form of the hydrogen ion often encountered in biochemistry, see Hydronium. Proton The quark structure of the proton. (The color … Wikipedia
Mass–energy equivalence — E=MC2 redirects here. For other uses, see E=MC2 (disambiguation). 4 meter tall sculpture of Einstein s 1905 E = mc2 formula at the 2006 Walk of Ideas, Berlin, Germany In physics, mass–energy equivalence is the concept that the … Wikipedia
Proton–proton chain reaction — The proton–proton chain reaction dominates in stars the size of the Sun or smaller. The proton–proton chain reaction is one of several fusion reactions by which stars convert hydrogen to helium, the primary alternative being the CNO cycle. The… … Wikipedia
Proton-proton chain reaction — The proton proton chain reaction is one of several fusion reactions by which stars convert hydrogen to helium, the primary alternative being the CNO cycle. The proton proton chain dominates in stars the size of the Sun or smaller.Overcoming… … Wikipedia
Mass — This article is about the scientific concept. For the substance of which all physical objects consist, see Matter. For other uses, see Mass (disambiguation). Classical mechanics … Wikipedia
mass spectrometry — or mass spectroscopy Analytic technique by which chemical substances are identified by sorting gaseous ions by mass using electric and magnetic fields. A mass spectrometer uses electrical means to detect the sorted ions, while a mass spectrograph … Universalium
Mass number — The mass number (A), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. Because protons and neutrons both are baryons, the mass number A is identical… … Wikipedia
