Difference between revisions of "Meson"
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'''[[Electrical Charge|Charge]]''' | '''[[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> | + | 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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<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 one its [[strange-quark]] with a [[Electrical Charge|charge]] of <math>-\frac{1}{3}</math> | + | K<sup>-</sup> has a [[Negative Charge|negative charge]]. This can be achieved with one 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> |
Revision as of 15:25, 18 July 2019
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 |
\(q=+\frac{2}{3}\) | \(S=0\) | |
\(q=-\frac{2}{3}\) | \(S=0\) | |
\(q=-\frac{1}{3}\) | \(S=0\) | |
\(q=+\frac{1}{3}\) | \(S=0\) | |
\(q=-\frac{1}{3}\) | \(S=-1\) | |
\(q=+\frac{1}{3}\) | \(S=+1\) |
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 one 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. |