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1. Shard Calculation

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Response:

Calculated Shard: 84 (from laksa049)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa084.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/hadron.html\')), getAhrefsUnparsedNoserviceFromURL(\'http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/hadron.html\'))) FORMAT JSONEachRow'

Response:

{"found_url":"http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/hadron.html","crawl_time":1771903304,"first_indexed_time":1376291431,"http_code":200,"src_unparsed":"edu,gsu!phy-astr,hyperphysics,\/hbase\/Particles\/hadron.html h80","src_root_hash":"18260356090813802484","history_drop_reason":null,"meta_title":"Hadrons, baryons, mesons","meta_descriptions":[],"attrs_boilerpipe_text":"pion\nThe pion, being the lightest meson,  can be used to predict the maximum range of the\nstrong interaction\n. The strong interaction properties of the three pions are identical. The connection between pions and the strong force was proposed by\nHideki Yukawa\n. Yukawa worked out a potential for the force and predicted its mass based on the\nuncertainty principle\nfrom measurements of the apparent\nrange\nof the strong force in nuclei. We now know that the pion is a meson, a composite particle, and the current view is that the strong interaction is an interaction between quarks, but the Yukawa theory stimulated a major advance in the understanding of the strong interaction and\nexchange forces\nin general.\nParticle\nSymbol\nAnti-\nparticle\nMakeup\nRest mass\nMeV\/c\n2\nS\nC\nB\nLifetime\nDecay Modes\nPion\n&#960\n+\n&#960\n-\n139.6\n0\n0\n0\n2.60\nx10\n-8\n&#956\n+\n&#957\n&#956\nPion\n&#960\n0\nSelf\n135.0\n0\n0\n0\n0.83\nx10\n-16\n2&#947\nThe neutral pion decays to two photons (gamma rays) 98.8% of the time. The decay is by the electromagnetic interaction on a time scale of about 10\n-16\nseconds. \rThe positive and negative pions have longer lifetimes of about 2.6 x 10\n-8\ns.\nThe negative pion decays into a muon and a muon antineutrino as illustrated below. This decay is puzzling upon first examination because the decay into an electron plus an electron antineutrino yields much more energy. Usually the pathway with the greatest energy yield is the preferred pathway. This suggests that some symmetry is acting to inhibit the electron decay pathway.\nThe symmetry which suppresses the electron pathway is that of angular momentum, as described by Griffiths. Since the negative pion has spin zero, the electron and antineutrino must be emitted with opposite spins to preserve net zero spin. But the antineutrino is always\nright-handed\n, so this implies that the electron must be emitted with spin in the direction of its linear momentum (i.e., also right-handed). But if the electron were massless, it would (like the neutrino) only exist as a left-handed particle, and the electron pathway would be completely prohibited. So the suppression of the electron pathway is attributed to the fact that the electron's small mass greatly favors the left-handed symmetry, thus inhibiting the decay. Weak interaction theory predicts that the fraction of muons decaying into electrons should be 1.28 x 10\n-4\nand the measured branching ratio is 1.23 +\/- 0.02 x  10\n-4\n.\nBeing composed of an up and an antidown\nquark\n, the positive pion would be expected to have a mass about 2\/3 that of a proton, yet its mass is only about 1\/6 of that of the proton! This is an example of how\nhadron masses\ndepend upon the dynamics inside the particle, and not just upon the quarks contained.\nPions interact with nuclei and transform a neutron to a proton or vice versa as indicated by the\nFeynman diagram\nabove. Though this diagram is labeled as the diagram for the strong force, the strong force is fundamentally an interaction between quarks via gluons. Slaven terms this diagram an example of the \"residual strong force\" since it is depicted between colorless particles. He makes the analogy with the \"residual electromagnetic force\" between atoms which are electrically neutral. The interactions depicted below appear to be consistent with this picture and can be viewed as interactions between quarks which result in the production of a different distribution of quarks.\nThe pions &#960\n+\nand &#960\n-\nhave spin zero and negative intrinsic parity (\nRohlf\nSec 17-2).\nIndex\nParticle concepts\nReferences\nGriffiths\nSec 10.4\nReview of Particle Physics, 2010 p623\nSlaven, Morningside.edu","attrs_markdown":"|   |   |\n|---|---|\n|   | [Index](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hframe.html)  [Particle concepts](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/parcon.html)  References [Serway](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quaref.html) Ch. 47  [Giancoli](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quaref.html) Ch. 32  [Griffiths](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quaref.html) |\n|   |   |\n| [Meson diagram](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/haddia.html#c1) | [Table of mesons](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/meson.html#c1) |\n|   | [Go Back](Javascript:history.go\\(-1\\)) |\n|   |   |\n| [HyperPhysics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hph.html)\\*\\*\\*\\*\\* [Quantum Physics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quacon.html#quacon) | *R Nave* |\n\n|   |   |   |   |   |   |   |   |   |   |\n|---|---|---|---|---|---|---|---|---|---|\n|   | [Index](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hframe.html)  [Particle concepts](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/parcon.html)  References [Griffiths](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quaref.html) Sec 10.4  [Review of Particle Physics, 2010 p623](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quaref.html)  [Slaven, Morningside.edu](https:\/\/webs.morningside.edu\/slaven\/Physics\/micro\/micro6.html) |   |   |   |   |   |   |   |   |\n|   |   |   |   |   |   |   |   |   |   |\n| Particle | Symbol | Anti- particle | Makeup | Rest mass MeV\/c2 | S | C | B | Lifetime | Decay Modes |\n| Pion | \\&\\#960\\+ | \\&\\#960\\- | ![](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/imgpar\/uad.png) | 139\\.6 | 0 | 0 | 0 | 2\\.60 x10\\-8 | \\&\\#956\\+\\&\\#957\\&\\#956 |\n| Pion | \\&\\#9600 | Self | ![](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/imgpar\/pio.gif) | 135\\.0 | 0 | 0 | 0 | 0\\.83 x10\\-16 | 2\\&\\#947 |\n|   |   |   |   |   |   |   |   |   |   |\n| The pion is a [meson](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/hadron.html#c1). The \\&\\#960\\+ is considered to be made up of an up and an anti-down  [quark](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/quark.html#c1). The neutral pion is considered to be a combination of quark-antiquark pairs: ![](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/imgpar\/pio.gif) | ![](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/imgpar\/pion2.gif) |   |   |   |   |   |   |   |   |\n|   |   |   |   |   |   |   |   |   |   |\n| [Energetics of charged pion decay](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/piondec.html#c1) |   |   |   |   |   |   |   |   |   |\n|   |   |   |   |   |   |   |   |   |   |\n| [Meson diagram](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/haddia.html#c1) | [Table of mesons](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/meson.html#c1) |   |   |   |   |   |   |   |   |\n|   | [Go Back](Javascript:history.go\\(-1\\)) |   |   |   |   |   |   |   |   |\n|   |   |   |   |   |   |   |   |   |   |\n| [HyperPhysics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hph.html)\\*\\*\\*\\*\\* [Quantum Physics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quacon.html#quacon) | *R Nave* |   |   |   |   |   |   |   |   |\n\n|   |   |   |   |   |   |   |   |   |   |\n|---|---|---|---|---|---|---|---|---|---|\n|   | [Index](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hframe.html)  [Particle concepts](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/parcon.html) |   |   |   |   |   |   |   |   |\n|   |   |   |   |   |   |   |   |   |   |\n| Particle | Symbol | Anti- particle | Makeup | Rest mass MeV\/c2 | S | C | B | Lifetime | Decay Modes |\n| J\/Psi | J\/\\&\\#968 | Self | ![](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/imgpar\/cac.png) | 3096\\.9 | 0 | 0 | 0 | 0\\.8 x10\\-20 | e\\+e\\-, \\&\\#956\\+\\&\\#956\\-... |\n|   |   |   |   |   |   |   |   |   |   |\n| [Meson diagram](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/haddia.html#c1) | [Table of mesons](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/meson.html#c1) |   |   |   |   |   |   |   |   |\n|   | [Go Back](Javascript:history.go\\(-1\\)) |   |   |   |   |   |   |   |   |\n|   |   |   |   |   |   |   |   |   |   |\n| [HyperPhysics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hph.html)\\*\\*\\*\\*\\* [Quantum Physics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quacon.html#quacon) | *R Nave* |   |   |   |   |   |   |   |   |\n\n|   |   |   |   |   |   |   |   |   |   |\n|---|---|---|---|---|---|---|---|---|---|\n|   | [Index](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hframe.html)  [Particle concepts](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/parcon.html) |   |   |   |   |   |   |   |   |\n|   |   |   |   |   |   |   |   |   |   |\n| Particle | Symbol | Anti- particle | Makeup | Rest mass MeV\/c2 | S | C | B | Lifetime | Decay Modes |\n| Upsilon | \\&\\#978 | Self | ![](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/imgpar\/bab.png) | 9460\\.4 | 0 | 0 | 0 | 1\\.3 x10\\-20 | e\\+e\\-, \\&\\#956\\+\\&\\#956\\-.. |\n|   |   |   |   |   |   |   |   |   |   |\n| [Meson diagram](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/haddia.html#c1) | [Table of mesons](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/meson.html#c1) |   |   |   |   |   |   |   |   |\n|   | [Go Back](Javascript:history.go\\(-1\\)) |   |   |   |   |   |   |   |   |\n|   |   |   |   |   |   |   |   |   |   |\n| [HyperPhysics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hph.html)\\*\\*\\*\\*\\* [Quantum Physics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quacon.html#quacon) | *R Nave* |   |   |   |   |   |   |   |   |\n\n|   |   |\n|---|---|\n| Hadrons Particles that interact by the [strong interaction](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/forces\/funfor.html#c2) are called hadrons. This general classification includes [mesons](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/hadron.html#c1) and [baryons](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/hadron.html#c6) but specifically excludes [leptons](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/lepton.html#c1), which do not interact by the strong force. The [weak interaction](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/forces\/funfor.html#c4) acts on both hadrons and leptons. Hadrons are viewed as being composed of [quarks](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/quark.html#c1), either as quark-antiquark pairs (mesons) or as three quarks (baryons). There is much more to the picture than this, however, because the constituent quarks are surrounded by a cloud of [gluons](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/expar.html#c1), the exchange particles for the [color force](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/forces\/color.html#c1). There was a recent claim of observation of particles with five quarks ([pentaquark](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/pquark.html#c1)), but further experimentation has not borne it out. | [Index](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hframe.html)  [Particle concepts](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/parcon.html) |\n|   | [Go Back](Javascript:history.go\\(-1\\)) |\n|   |   |\n| [HyperPhysics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hph.html)\\*\\*\\*\\*\\* [Quantum Physics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quacon.html#quacon) | *R Nave* |\n\n|   |   |\n|---|---|\n|   | [Index](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hframe.html)  [Particle concepts](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/parcon.html)  Reference [Serway](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quaref.html) Ch. 47 |\n|   |   |\n| [Table of Baryons](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/baryon.html#c1) |   |\n|   |   |\n| [Baryon diagram](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/haddia.html#c3) |   |\n|   | [Go Back](Javascript:history.go\\(-1\\)) |\n|   |   |\n| [HyperPhysics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hph.html)\\*\\*\\*\\*\\* [Quantum Physics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quacon.html#quacon) | *R Nave* |\n\n|   |   |\n|---|---|\n| Hideki Yukawa and the Pion Once quantum electrodyamics had produced the picture of the [electromagnetic force](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/forces\/funfor.html#c3) as a process of exchanging photons, the question of whether or not the other forces were also [exchange forces](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/forces\/exchg.html#c1) was a natural one. In 1935, Hideki Yukawa reasoned that the electromagnetic force was infinite in range because the exchange particle was massless. He proposed that the short range [strong force](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/forces\/funfor.html#c2) came about from the exchange of a massive particle which he called a meson. By observing that the [effective range](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/forces\/exchg.html#c3) of the nuclear force was on the order of a fermi, a mass for the exchange particle could be predicted using the uncertainty principle. The predicted particle mass was about 100 MeV. It did not receive immediate attention since no one knew of a particle which fit that description. In 1937 a particle of mass close to Yukawa's prediction was discovered in cosmic rays by Anderson & Neddermeyer and by Street & Stevenson in independent experiments. This particle, the [muon](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/lepton.html#c3), turned out not to interact by the strong interaction. Hans Bethe and Robert Marshak predicted that the muon could be a decay product of the particle sought. In 1947, Lattes, Muirhead, Occhialini and Powell conducted a high altitude experiment, flying photographic emulsions at 3000 meters. These emulsions revealed the [pion](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/hadron.html#c2), which met all the requirements of the Yukawa particle. We now know that the pion is a [meson](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/Particles\/hadron.html#c1), a composite particle, and the current view is that the strong interaction is an interaction between quarks, but the Yukawa theory stimulated a major advance in the understanding of the strong interaction. | [Index](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hframe.html)  References [Rohlf](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quaref.html), Ch 17.  [Lattes, et al.](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quaref.html) |\n|   | [Go Back](Javascript:history.go\\(-1\\)) |\n|   |   |\n| [HyperPhysics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/hph.html)\\*\\*\\*\\*\\* [Quantum Physics](http:\/\/hyperphysics.phy-astr.gsu.edu\/hbase\/quacon.html#quacon) | *R Nave* |","attrs_readable_markdown":null,"meta_canonical":null}

3. Robots.txt Check

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4. Spam/Ban Check

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5. Seen Status Check

ℹ️ Skipped - page is already crawled

📄

INDEXABLE

✅

CRAWLED

1 month ago

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ROBOTS ALLOWED

Page Info Filters

Filter	Status	Condition	Details
HTTP status	PASS	`download_http_code = 200`	HTTP 200
Age cutoff	PASS	`download_stamp > now() - 6 MONTH`	1.7 months ago
History drop	PASS	`isNull(history_drop_reason)`	No drop reason
Spam/ban	PASS	`fh_dont_index != 1 AND ml_spam_score = 0`	ml_spam_score=0
Canonical	PASS	`meta_canonical IS NULL OR = '' OR = src_unparsed`	Not set

Page Details

Property	Value
URL	http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/hadron.html
Last Crawled	2026-02-24 03:21:44 (1 month ago)
First Indexed	2013-08-12 07:10:31 (12 years ago)
HTTP Status Code	200
Meta Title	Hadrons, baryons, mesons
Meta Description	null
Meta Canonical	null
Boilerpipe Text	pion The pion, being the lightest meson, can be used to predict the maximum range of the strong interaction . The strong interaction properties of the three pions are identical. The connection between pions and the strong force was proposed by Hideki Yukawa . Yukawa worked out a potential for the force and predicted its mass based on the uncertainty principle from measurements of the apparent range of the strong force in nuclei. We now know that the pion is a meson, a composite particle, and the current view is that the strong interaction is an interaction between quarks, but the Yukawa theory stimulated a major advance in the understanding of the strong interaction and exchange forces in general. Particle Symbol Anti- particle Makeup Rest mass MeV/c 2 S C B Lifetime Decay Modes Pion &#960 + &#960 - 139.6 0 0 0 2.60 x10 -8 &#956 + &#957 &#956 Pion &#960 0 Self 135.0 0 0 0 0.83 x10 -16 2&#947 The neutral pion decays to two photons (gamma rays) 98.8% of the time. The decay is by the electromagnetic interaction on a time scale of about 10 -16 seconds. The positive and negative pions have longer lifetimes of about 2.6 x 10 -8 s. The negative pion decays into a muon and a muon antineutrino as illustrated below. This decay is puzzling upon first examination because the decay into an electron plus an electron antineutrino yields much more energy. Usually the pathway with the greatest energy yield is the preferred pathway. This suggests that some symmetry is acting to inhibit the electron decay pathway. The symmetry which suppresses the electron pathway is that of angular momentum, as described by Griffiths. Since the negative pion has spin zero, the electron and antineutrino must be emitted with opposite spins to preserve net zero spin. But the antineutrino is always right-handed , so this implies that the electron must be emitted with spin in the direction of its linear momentum (i.e., also right-handed). But if the electron were massless, it would (like the neutrino) only exist as a left-handed particle, and the electron pathway would be completely prohibited. So the suppression of the electron pathway is attributed to the fact that the electron's small mass greatly favors the left-handed symmetry, thus inhibiting the decay. Weak interaction theory predicts that the fraction of muons decaying into electrons should be 1.28 x 10 -4 and the measured branching ratio is 1.23 +/- 0.02 x 10 -4 . Being composed of an up and an antidown quark , the positive pion would be expected to have a mass about 2/3 that of a proton, yet its mass is only about 1/6 of that of the proton! This is an example of how hadron masses depend upon the dynamics inside the particle, and not just upon the quarks contained. Pions interact with nuclei and transform a neutron to a proton or vice versa as indicated by the Feynman diagram above. Though this diagram is labeled as the diagram for the strong force, the strong force is fundamentally an interaction between quarks via gluons. Slaven terms this diagram an example of the "residual strong force" since it is depicted between colorless particles. He makes the analogy with the "residual electromagnetic force" between atoms which are electrically neutral. The interactions depicted below appear to be consistent with this picture and can be viewed as interactions between quarks which result in the production of a different distribution of quarks. The pions &#960 + and &#960 - have spin zero and negative intrinsic parity ( Rohlf Sec 17-2). Index Particle concepts References Griffiths Sec 10.4 Review of Particle Physics, 2010 p623 Slaven, Morningside.edu
Markdown	\| \| \| \|---\|---\| \| \| [Index](http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html) [Particle concepts](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/parcon.html) References [Serway](http://hyperphysics.phy-astr.gsu.edu/hbase/quaref.html) Ch. 47 [Giancoli](http://hyperphysics.phy-astr.gsu.edu/hbase/quaref.html) Ch. 32 [Griffiths](http://hyperphysics.phy-astr.gsu.edu/hbase/quaref.html) \| \| \| \| \| [Meson diagram](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/haddia.html#c1) \| [Table of mesons](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/meson.html#c1) \| \| \| [Go Back](Javascript:history.go\(-1\)) \| \| \| \| \| [HyperPhysics](http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html)\\\\\* [Quantum Physics](http://hyperphysics.phy-astr.gsu.edu/hbase/quacon.html#quacon) \| R Nave \| \| \| \| \| \| \| \| \| \| \| \| \|---\|---\|---\|---\|---\|---\|---\|---\|---\|---\| \| \| [Index](http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html) [Particle concepts](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/parcon.html) References [Griffiths](http://hyperphysics.phy-astr.gsu.edu/hbase/quaref.html) Sec 10.4 [Review of Particle Physics, 2010 p623](http://hyperphysics.phy-astr.gsu.edu/hbase/quaref.html) [Slaven, Morningside.edu](https://webs.morningside.edu/slaven/Physics/micro/micro6.html) \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| Particle \| Symbol \| Anti- particle \| Makeup \| Rest mass MeV/c2 \| S \| C \| B \| Lifetime \| Decay Modes \| \| Pion \| \&\#960\+ \| \&\#960\- \| ![](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/imgpar/uad.png) \| 139\.6 \| 0 \| 0 \| 0 \| 2\.60 x10\-8 \| \&\#956\+\&\#957\&\#956 \| \| Pion \| \&\#9600 \| Self \| ![](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/imgpar/pio.gif) \| 135\.0 \| 0 \| 0 \| 0 \| 0\.83 x10\-16 \| 2\&\#947 \| \| \| \| \| \| \| \| \| \| \| \| \| The pion is a [meson](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/hadron.html#c1). The \&\#960\+ is considered to be made up of an up and an anti-down [quark](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/quark.html#c1). The neutral pion is considered to be a combination of quark-antiquark pairs: ![](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/imgpar/pio.gif) \| ![](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/imgpar/pion2.gif) \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| [Energetics of charged pion decay](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/piondec.html#c1) \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| [Meson diagram](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/haddia.html#c1) \| [Table of mesons](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/meson.html#c1) \| \| \| \| \| \| \| \| \| \| \| [Go Back](Javascript:history.go\(-1\)) \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| [HyperPhysics](http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html)\\\\\* [Quantum Physics](http://hyperphysics.phy-astr.gsu.edu/hbase/quacon.html#quacon) \| R Nave \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \|---\|---\|---\|---\|---\|---\|---\|---\|---\|---\| \| \| [Index](http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html) [Particle concepts](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/parcon.html) \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| Particle \| Symbol \| Anti- particle \| Makeup \| Rest mass MeV/c2 \| S \| C \| B \| Lifetime \| Decay Modes \| \| J/Psi \| J/\&\#968 \| Self \| ![](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/imgpar/cac.png) \| 3096\.9 \| 0 \| 0 \| 0 \| 0\.8 x10\-20 \| e\+e\-, \&\#956\+\&\#956\-... \| \| \| \| \| \| \| \| \| \| \| \| \| [Meson diagram](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/haddia.html#c1) \| [Table of mesons](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/meson.html#c1) \| \| \| \| \| \| \| \| \| \| \| [Go Back](Javascript:history.go\(-1\)) \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| [HyperPhysics](http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html)\\\\\* [Quantum Physics](http://hyperphysics.phy-astr.gsu.edu/hbase/quacon.html#quacon) \| R Nave \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \|---\|---\|---\|---\|---\|---\|---\|---\|---\|---\| \| \| [Index](http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html) [Particle concepts](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/parcon.html) \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| Particle \| Symbol \| Anti- particle \| Makeup \| Rest mass MeV/c2 \| S \| C \| B \| Lifetime \| Decay Modes \| \| Upsilon \| \&\#978 \| Self \| ![](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/imgpar/bab.png) \| 9460\.4 \| 0 \| 0 \| 0 \| 1\.3 x10\-20 \| e\+e\-, \&\#956\+\&\#956\-.. \| \| \| \| \| \| \| \| \| \| \| \| \| [Meson diagram](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/haddia.html#c1) \| [Table of mesons](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/meson.html#c1) \| \| \| \| \| \| \| \| \| \| \| [Go Back](Javascript:history.go\(-1\)) \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| \| [HyperPhysics](http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html)\\\\\* [Quantum Physics](http://hyperphysics.phy-astr.gsu.edu/hbase/quacon.html#quacon) \| R Nave \| \| \| \| \| \| \| \| \| \| \| \| \|---\|---\| \| Hadrons Particles that interact by the [strong interaction](http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html#c2) are called hadrons. This general classification includes [mesons](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/hadron.html#c1) and [baryons](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/hadron.html#c6) but specifically excludes [leptons](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/lepton.html#c1), which do not interact by the strong force. The [weak interaction](http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html#c4) acts on both hadrons and leptons. Hadrons are viewed as being composed of [quarks](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/quark.html#c1), either as quark-antiquark pairs (mesons) or as three quarks (baryons). There is much more to the picture than this, however, because the constituent quarks are surrounded by a cloud of [gluons](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/expar.html#c1), the exchange particles for the [color force](http://hyperphysics.phy-astr.gsu.edu/hbase/forces/color.html#c1). There was a recent claim of observation of particles with five quarks ([pentaquark](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/pquark.html#c1)), but further experimentation has not borne it out. \| [Index](http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html) [Particle concepts](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/parcon.html) \| \| \| [Go Back](Javascript:history.go\(-1\)) \| \| \| \| \| [HyperPhysics](http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html)\\\\\* [Quantum Physics](http://hyperphysics.phy-astr.gsu.edu/hbase/quacon.html#quacon) \| R Nave \| \| \| \| \|---\|---\| \| \| [Index](http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html) [Particle concepts](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/parcon.html) Reference [Serway](http://hyperphysics.phy-astr.gsu.edu/hbase/quaref.html) Ch. 47 \| \| \| \| \| [Table of Baryons](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/baryon.html#c1) \| \| \| \| \| \| [Baryon diagram](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/haddia.html#c3) \| \| \| \| [Go Back](Javascript:history.go\(-1\)) \| \| \| \| \| [HyperPhysics](http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html)\\\\\* [Quantum Physics](http://hyperphysics.phy-astr.gsu.edu/hbase/quacon.html#quacon) \| R Nave \| \| \| \| \|---\|---\| \| Hideki Yukawa and the Pion Once quantum electrodyamics had produced the picture of the [electromagnetic force](http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html#c3) as a process of exchanging photons, the question of whether or not the other forces were also [exchange forces](http://hyperphysics.phy-astr.gsu.edu/hbase/forces/exchg.html#c1) was a natural one. In 1935, Hideki Yukawa reasoned that the electromagnetic force was infinite in range because the exchange particle was massless. He proposed that the short range [strong force](http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html#c2) came about from the exchange of a massive particle which he called a meson. By observing that the [effective range](http://hyperphysics.phy-astr.gsu.edu/hbase/forces/exchg.html#c3) of the nuclear force was on the order of a fermi, a mass for the exchange particle could be predicted using the uncertainty principle. The predicted particle mass was about 100 MeV. It did not receive immediate attention since no one knew of a particle which fit that description. In 1937 a particle of mass close to Yukawa's prediction was discovered in cosmic rays by Anderson & Neddermeyer and by Street & Stevenson in independent experiments. This particle, the [muon](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/lepton.html#c3), turned out not to interact by the strong interaction. Hans Bethe and Robert Marshak predicted that the muon could be a decay product of the particle sought. In 1947, Lattes, Muirhead, Occhialini and Powell conducted a high altitude experiment, flying photographic emulsions at 3000 meters. These emulsions revealed the [pion](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/hadron.html#c2), which met all the requirements of the Yukawa particle. We now know that the pion is a [meson](http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/hadron.html#c1), a composite particle, and the current view is that the strong interaction is an interaction between quarks, but the Yukawa theory stimulated a major advance in the understanding of the strong interaction. \| [Index](http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html) References [Rohlf](http://hyperphysics.phy-astr.gsu.edu/hbase/quaref.html), Ch 17. [Lattes, et al.](http://hyperphysics.phy-astr.gsu.edu/hbase/quaref.html) \| \| \| [Go Back](Javascript:history.go\(-1\)) \| \| \| \| \| [HyperPhysics](http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html)\\\\\* [Quantum Physics](http://hyperphysics.phy-astr.gsu.edu/hbase/quacon.html#quacon) \| R Nave \|
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