From Surf Wiki (app.surf) — the open knowledge base
Up quark
Type of quark
Type of quark
| Field | Value |
|---|---|
| name | Up quark |
| composition | elementary particle |
| statistics | fermionic |
| group | quark |
| generation | first |
| interaction | strong, weak, electromagnetic, gravity |
| antiparticle | up antiquark () |
| theorized | Murray Gell-Mann (1964)George Zweig (1964) |
| discovered | SLAC (1968) |
| symbol | |
| mass | |
| author | M. Tanabashi et al. (Particle Data Group) |
| title | Review of Particle Physics |
| year | 2018 |
| doi | 10.1103/PhysRevD.98.030001 |
| volume | 98 |
| issue | 3 |
| pages | 1–708 |
| journal | Physical Review D |
| pmid | 10020536 |
| url | http://pdglive.lbl.gov/DataBlock.action?node=Q123UM |
| doi-access | free |
| bibcode | 2018PhRvD..98c0001T |
| hdl | 10044/1/68623 |
| hdl-access | free |
| decay_particle | stable or down quark + positron + electron neutrino |
| electric_charge | + *e* |
| color_charge | yes |
| spin | *ħ* |
| weak_isospin | LH: +, RH: 0 |
| weak_hypercharge | LH: +, RH: + |
|doi-access=free |hdl-access=free
The up quark or u quark (symbol: u) is the lightest of all quarks, a type of elementary particle, and a significant constituent of matter. It, along with the down quark, forms the neutrons (one up quark, two down quarks) and protons (two up quarks, one down quark) of atomic nuclei. It is part of the first generation of matter, has an electric charge of + e and a bare mass of . Like all quarks, the up quark is an elementary fermion with spin , and experiences all four fundamental interactions: gravitation, electromagnetism, weak interactions, and strong interactions. The antiparticle of the up quark is the up antiquark (sometimes called antiup quark or simply antiup), which differs from it only in that some of its properties, such as charge have equal magnitude but opposite sign.
Its existence (along with that of the down and strange quarks) was postulated in 1964 by Murray Gell-Mann and George Zweig to explain the Eightfold Way classification scheme of hadrons. The up quark was first observed by experiments at the Stanford Linear Accelerator Center in 1968.
History
In the beginnings of particle physics (first half of the 20th century), hadrons such as protons, neutrons and pions were thought to be elementary particles. However, as new hadrons were discovered, the 'particle zoo' grew from a few particles in the early 1930s and 1940s to several dozens of them in the 1950s. The relationships between each of them were unclear until 1961, when Murray Gell-Mann
This classification scheme organized the hadrons into isospin multiplets, but the physical basis behind it was still unclear. In 1964, Gell-Mann |access-date=2008-09-23 |display-authors=8 |doi-access=free |display-authors=etal |access-date = 2008-09-29 |archive-url = https://web.archive.org/web/20081225093044/http://www.hueuni.edu.vn/hueuni/en/news_detail.php?NewsID=1606&PHPSESSID=909807ffc5b9c0288cc8d137ff063c72 |archive-date = 2008-12-25
At first people were reluctant to describe the three bodies as quarks, instead preferring Richard Feynman's parton description, |display-authors=etal |url-access=registration
Mass
Despite being extremely common, the bare mass of the up quark is not well determined, but probably lies between 1.8 and . |access-date=2013-02-21 |display-authors=etal
When found in mesons (particles made of one quark and one antiquark) or baryons (particles made of three quarks), the 'effective mass' (or 'dressed' mass) of quarks becomes greater because of the binding energy caused by the gluon field between each quark (see Mass–energy equivalence). The bare mass of up quarks is so light, it cannot be straightforwardly calculated because relativistic effects have to be taken into account.
References
References
- Cho, Adrian. (April 2010). "Mass of the Common Quark Finally Nailed Down". Science Magazine.
This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.
Ask Mako anything about Up quark — get instant answers, deeper analysis, and related topics.
Research with MakoFree with your Surf account
Create a free account to save articles, ask Mako questions, and organize your research.
Sign up freeThis content may have been generated or modified by AI. CloudSurf Software LLC is not responsible for the accuracy, completeness, or reliability of AI-generated content. Always verify important information from primary sources.
Report