Difference between revisions of "Meson"
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===About Mesons=== | ===About Mesons=== | ||
: '''Mesons''' have a very short [[Half Life|half life]], [[Radioactive Decay|decaying]] via the [[Weak Nuclear Interaction|weak nuclear interaction]] or though the [[quark]]-[[antiquark]] pair [[annihilation|annihilating]] one another. | : '''Mesons''' have a very short [[Half Life|half life]], [[Radioactive Decay|decaying]] via the [[Weak Nuclear Interaction|weak nuclear interaction]] or though the [[quark]]-[[antiquark]] pair [[annihilation|annihilating]] one another. | ||
| − | : '''Mesons''' consisting of the [[quark]]s; [[up-quark]], [[down-quark]] and [[strange-quark]] are divided into two main categories; [[π-meson]]s and [[k- | + | : '''Mesons''' consisting of the [[quark]]s; [[up-quark]], [[down-quark]] and [[strange-quark]] are divided into two main categories; [[π-meson]]s and [[k-meson]]s. |
: '''[[K-meson]]s''' have a [[strangeness]] of +1 or -1. However, [[π-meson]]s do not carry [[strangeness]]. | : '''[[K-meson]]s''' have a [[strangeness]] of +1 or -1. However, [[π-meson]]s do not carry [[strangeness]]. | ||
: '''Mesons''' are affected by the: | : '''Mesons''' are affected by the: | ||
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===Determining Meson Composition=== | ===Determining Meson Composition=== | ||
| − | ''NB: You do not need to memorise the exact composition of a given '''meson'''. However, you should be able to determine | + | ''NB: You do not need to memorise the exact composition of a given '''meson'''. However, you should be able to determine a possible [[quark]] composition given the [[Electrical Charge|charge]] and [[strangeness]] of the [[meson]] and by remembering the properties of the [[up-quark]], [[down-quark]] and [[strange-quark]].'' |
: '''Mesons''' can be shown in the following diagram: | : '''Mesons''' can be shown in the following diagram: | ||
{| border="1" style="border-collapse:collapse" | {| border="1" style="border-collapse:collapse" | ||
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====Examples==== | ====Examples==== | ||
| − | {| | + | {| border="1" style="border-collapse:collapse" |
|+ This table is for referencing the properties of the [[quark]]s. | |+ This table is for referencing the properties of the [[quark]]s. | ||
| style="height:20px; width:200px; text-align:center;"|'''[[Quark]]''' | | style="height:20px; width:200px; text-align:center;"|'''[[Quark]]''' | ||
| − | | style="height:20px; width:200px; text-align:center;"|[[Electrical Charge|'''Charge''']] | + | | style="height:20px; width:200px; text-align:center;"|[[Electrical Charge|'''Charge''']]/[[Elementary Charge|e]] |
| style="height:20px; width:200px; text-align:center;"|'''[[Strangeness]]''' | | style="height:20px; width:200px; text-align:center;"|'''[[Strangeness]]''' | ||
|- | |- | ||
| style="height:20px; width:200px; text-align:center;"| | | style="height:20px; width:200px; text-align:center;"| | ||
| − | [[Up-quark]] | + | [[Up-quark]] (<math>u</math>) |
| style="height:20px; width:200px; text-align:center;"|<math>q=+\frac{2}{3}</math> | | style="height:20px; width:200px; text-align:center;"|<math>q=+\frac{2}{3}</math> | ||
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|- | |- | ||
| style="height:20px; width:200px; text-align:center;"| | | style="height:20px; width:200px; text-align:center;"| | ||
| − | [[Antiup-quark]] | + | [[Antiup-quark]] (<math>\bar{u}</math>) |
| style="height:20px; width:200px; text-align:center;"|<math>q=-\frac{2}{3}</math> | | style="height:20px; width:200px; text-align:center;"|<math>q=-\frac{2}{3}</math> | ||
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|- | |- | ||
| style="height:20px; width:200px; text-align:center;"| | | style="height:20px; width:200px; text-align:center;"| | ||
| − | [[Down-quark]] | + | [[Down-quark]] (<math>d</math>) |
| style="height:20px; width:200px; text-align:center;"|<math>q=-\frac{1}{3}</math> | | style="height:20px; width:200px; text-align:center;"|<math>q=-\frac{1}{3}</math> | ||
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|- | |- | ||
| style="height:20px; width:200px; text-align:center;"| | | style="height:20px; width:200px; text-align:center;"| | ||
| − | [[Antidown-quark]] | + | [[Antidown-quark]] (<math>\bar{d}</math>) |
| style="height:20px; width:200px; text-align:center;"|<math>q=+\frac{1}{3}</math> | | style="height:20px; width:200px; text-align:center;"|<math>q=+\frac{1}{3}</math> | ||
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|- | |- | ||
| style="height:20px; width:200px; text-align:center;"| | | style="height:20px; width:200px; text-align:center;"| | ||
| − | [[Strange-quark]] | + | [[Strange-quark]] (<math>s</math>) |
| style="height:20px; width:200px; text-align:center;"|<math>q=-\frac{1}{3}</math> | | style="height:20px; width:200px; text-align:center;"|<math>q=-\frac{1}{3}</math> | ||
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|- | |- | ||
| style="height:20px; width:200px; text-align:center;"| | | style="height:20px; width:200px; text-align:center;"| | ||
| − | [[Antistrange-quark]] | + | [[Antistrange-quark]] (<math>\bar{s}</math>) |
| style="height:20px; width:200px; text-align:center;"|<math>q=+\frac{1}{3}</math> | | style="height:20px; width:200px; text-align:center;"|<math>q=+\frac{1}{3}</math> | ||
| style="height:20px; width:200px; text-align:center;"|<math>S=+1</math> | | style="height:20px; width:200px; text-align:center;"|<math>S=+1</math> | ||
|} | |} | ||
| + | |||
{| class="wikitable" | {| class="wikitable" | ||
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|- | |- | ||
| style="height:20px; width:300px; text-align:left;" | | | style="height:20px; width:300px; text-align:left;" | | ||
| + | '''[[Strangeness]]''' | ||
π<sup>+</sup> has a [[strangeness]] of 0, therefore it contains no [[strange-quark]] or [[antistrange-quark]]. | π<sup>+</sup> has a [[strangeness]] of 0, therefore it contains no [[strange-quark]] or [[antistrange-quark]]. | ||
| − | π<sup>+</sup> has a [[Positive Charge|positive charge]]. This can be achieved with one [[Electrical Charge|charge]] of <math>+\frac{2}{3}</math> (an [[up-quark]]) and <math>+\frac{1}{3}</math> (an [[antidown-quark]]). | + | '''[[Electrical Charge|Charge]]''' |
| + | |||
| + | π<sup>+</sup> has a [[Positive Charge|positive charge]]. This can be achieved with one [[Electrical Charge|charge]] of <math>+\frac{2}{3}</math>[[Elementary Charge|e]] (an [[up-quark]]) and <math>+\frac{1}{3}</math>[[Elementary Charge|e]] (an [[antidown-quark]]). | ||
Since <math>+1 = +\frac{2}{3} + \frac{1}{3}</math> | Since <math>+1 = +\frac{2}{3} + \frac{1}{3}</math> | ||
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An up-antidown pair. | An up-antidown pair. | ||
| style="height:20px; width:300px; text-align:left;" | | | style="height:20px; width:300px; text-align:left;" | | ||
| + | '''[[Strangeness]]''' | ||
K<sup>-</sup> has a [[strangeness]] of -1, therefore it contains a [[strange-quark]]. | K<sup>-</sup> has a [[strangeness]] of -1, therefore it contains a [[strange-quark]]. | ||
| + | |||
| + | '''[[Electrical Charge|Charge]]''' | ||
<math>-1 = -\frac{1}{3} + x</math> | <math>-1 = -\frac{1}{3} + x</math> | ||
| − | K<sup>-</sup> has a [[Negative Charge|negative charge]]. This can be achieved with | + | K<sup>-</sup> has a [[Negative Charge|negative charge]]. This can be achieved with its [[strange-quark]] with a [[Electrical Charge|charge]] of <math>-\frac{1}{3}</math>[[Elementary Charge|e]] and another [[Electrical Charge|charge]] of <math>-\frac{2}{3}</math>[[Elementary Charge|e]] (an [[antiup-quark]]). |
Since <math>-1 = -\frac{1}{3} + -\frac{2}{3}</math> | Since <math>-1 = -\frac{1}{3} + -\frac{2}{3}</math> | ||
| − | Therefore <math>K^- = | + | Therefore <math>K^- = s + \bar{u}</math> |
A strange-antiup pair. | A strange-antiup pair. | ||
|} | |} | ||
Latest revision as of 09:40, 12 September 2021
Contents
Key Stage 5
Meaning
Mesons are a type of hadron consisting of a quark-antiquark pair.
About Mesons
- Mesons have a very short half life, decaying via the weak nuclear interaction or though the quark-antiquark pair annihilating one another.
- Mesons consisting of the quarks; up-quark, down-quark and strange-quark are divided into two main categories; π-mesons and k-mesons.
- K-mesons have a strangeness of +1 or -1. However, π-mesons do not carry strangeness.
- Mesons are affected by the:
Determining Meson Composition
NB: You do not need to memorise the exact composition of a given meson. However, you should be able to determine a possible quark composition given the charge and strangeness of the meson and by remembering the properties of the up-quark, down-quark and strange-quark.
- Mesons can be shown in the following diagram:
 |
| The composition of these mesons can be determined given their charge and strangeness. |
Examples
| Quark | Charge/e | Strangeness |
|
Up-quark (\(u\)) |
\(q=+\frac{2}{3}\) | \(S=0\) |
|
Antiup-quark (\(\bar{u}\)) |
\(q=-\frac{2}{3}\) | \(S=0\) |
|
Down-quark (\(d\)) |
\(q=-\frac{1}{3}\) | \(S=0\) |
|
Antidown-quark (\(\bar{d}\)) |
\(q=+\frac{1}{3}\) | \(S=0\) |
|
Strange-quark (\(s\)) |
\(q=-\frac{1}{3}\) | \(S=-1\) |
|
Antistrange-quark (\(\bar{s}\)) |
\(q=+\frac{1}{3}\) | \(S=+1\) |
| Determine the composition of the π+ | Determine the composition of the K- |
|
π+ has a strangeness of 0, therefore it contains no strange-quark or antistrange-quark. π+ has a positive charge. This can be achieved with one charge of \(+\frac{2}{3}\)e (an up-quark) and \(+\frac{1}{3}\)e (an antidown-quark). Since \(+1 = +\frac{2}{3} + \frac{1}{3}\) Therefore \(π^+ = u + \bar{d}\) An up-antidown pair. |
K- has a strangeness of -1, therefore it contains a strange-quark. \(-1 = -\frac{1}{3} + x\) K- has a negative charge. This can be achieved with its strange-quark with a charge of \(-\frac{1}{3}\)e and another charge of \(-\frac{2}{3}\)e (an antiup-quark). Since \(-1 = -\frac{1}{3} + -\frac{2}{3}\) Therefore \(K^- = s + \bar{u}\) A strange-antiup pair. |