Keyword density - Revision history

en>MrX: Reverted to revision 634142081 by 217.162.119.197 (talk): Per WP:ELNO. (TW)

2015-01-11T13:37:36Z

Reverted to revision 634142081 by 217.162.119.197 (talk): Per WP:ELNO. (TW)

← Older revision		Revision as of 15:37, 11 January 2015
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	~~{{About\|helicity in particle physics\|\|Helicity (disambiguation)}}~~		Hello and welcome. My name is Figures Wunder. South Dakota is where me and my spouse reside. One of the extremely best things in the globe for me is to do aerobics and now I'm attempting to make money with it. Hiring is my profession.<br><br>Here is my blog post: over the counter std test ([http://forums.cellphonedge.com/groups/valuable-guidance-for-successfully-treating-candidiasis/ hop over to here])

	~~In [[particle physics]], '''helicity'''~~ is ~~the projection~~ of the ~~[[Spin (physics)\|spin]] <math>\scriptstyle\vec S</math> onto~~ the ~~direction of momentum, <math>\scriptstyle \hat p</math>:~~
	~~:<math>h = \vec J\cdot\hat p = \vec L\cdot\hat p + \vec S\cdot \hat p = \vec S\cdot \hat p,\qquad \hat p = \frac{\vec p}{\left\|\vec p\right\|}</math>~~

	~~as the projection of orbital angular momentum along the linear momentum~~ is ~~zero, <math>\scriptstyle\vec L\cdot\hat p\,=\, 0</math>. Because the eigenvalues of spin with respect~~ to an axis have discrete values, the eigenvalues of helicity are also discrete. For a particle of spin ''S'', the eigenvalues of helicity are ''S'', {{nowrap\|''S'' − 1}}, ..., −''S''. The measured helicity of a spin ''S'' particle will range from −''S'' to ~~+''S''~~.

	~~In {{nowrap\|3 + 1}} dimensions, the [[little group]] for a [[massless particle]]~~ is ~~the [[Double covering group\|double cover]] of [[Euclidean group\|SE(2)]]~~. ~~This has [[unitary representation]]s which are invariant under the SE(2) "translations" and transform as e~~<~~sup~~>~~i''hθ''~~<~~/sup~~> under a SE(2) rotation by ''θ''. This is the helicity ''h'' representation. There is also another unitary representation which transforms non-trivially under the SE(2) translations. This is the ''continuous spin'' representation.

	~~In {{nowrap\|''d'' + 1}} dimensions, the little group~~ is the ~~double cover of SE({{nowrap\|''d'' − 1}})~~ (~~the case where {{nowrap\|''d'' ≤ 2}} is more complicated because of~~ [~~[anyon]]s, etc~~.). ~~As before, there are unitary representations which don't transform under the SE({{nowrap\|''d'' − 1}}) "translations" (the "standard" representations) and "continuous spin" representations.~~

	~~For massless [[spin~~-1/~~2\|spin-{{frac\|1\|2}} particles]], helicity is equivalent~~ to ~~the [[chirality (physics)\|chirality operator]~~] ~~multiplied by <math>\scriptstyle \frac{1}{2}\hbar</math>.~~

	~~==See also==~~
	* [[Wigner's classification]]
	* [[Chirality (physics)~~\|Chirality]]~~
	* [[Pauli–Lubanski pseudovector]]

	~~{{DEFAULTSORT:Helicity (Particle Physics)}}~~
	~~[[Category:Particle physics]]~~
	~~[[Category:Quantum field theory]]~~

	~~{{particle-stub}}~~

en>Yobot: WP:CHECKWIKI error fixes, removed stub tag using AWB (9456)

2013-09-01T09:52:06Z

WP:CHECKWIKI error fixes, removed stub tag using AWB (9456)

← Older revision		Revision as of 11:52, 1 September 2013
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	~~The individual who wrote~~ the ~~article is called Jayson Hirano and he completely digs that title. What me and my family members adore is~~ [~~http~~://~~www~~.~~seekavideo~~.~~com/playlist/2199/video/ free psychic reading] performing ballet but I~~'~~ve been taking on new things recently~~. ~~I've usually cherished [http://checkmates~~.co.~~za/index~~.~~php?do=/profile-56347/info/ love psychics] living in Kentucky but now I~~'~~m considering other options~~. ~~Distributing manufacturing has been his profession~~ for ~~some time~~.<br><br>~~Feel free to visit my web page :: tarot card readings~~ ([~~http://Www~~.~~Familysurvivalgroup~~.~~com~~/~~easy~~-~~methods-planting-looking-backyard~~/ ~~more resources~~])		{{About\|helicity in particle physics\|\|Helicity (disambiguation)}}

			In [[particle physics]], '''helicity''' is the projection of the [[Spin (physics)\|spin]] <math>\scriptstyle\vec S</math> onto the direction of momentum, <math>\scriptstyle \hat p</math>:
			:<math>h = \vec J\cdot\hat p = \vec L\cdot\hat p + \vec S\cdot \hat p = \vec S\cdot \hat p,\qquad \hat p = \frac{\vec p}{\left\|\vec p\right\|}</math>

			as the projection of orbital angular momentum along the linear momentum is zero, <math>\scriptstyle\vec L\cdot\hat p\,=\, 0</math>. Because the eigenvalues of spin with respect to an axis have discrete values, the eigenvalues of helicity are also discrete. For a particle of spin ''S'', the eigenvalues of helicity are ''S'', {{nowrap\|''S'' − 1}}, ..., −''S''. The measured helicity of a spin ''S'' particle will range from −''S'' to +''S''.

			In {{nowrap\|3 + 1}} dimensions, the [[little group]] for a [[massless particle]] is the [[Double covering group\|double cover]] of [[Euclidean group\|SE(2)]]. This has [[unitary representation]]s which are invariant under the SE(2) "translations" and transform as e<sup>i''hθ''</sup> under a SE(2) rotation by ''θ''. This is the helicity ''h'' representation. There is also another unitary representation which transforms non-trivially under the SE(2) translations. This is the ''continuous spin'' representation.

			In {{nowrap\|''d'' + 1}} dimensions, the little group is the double cover of SE({{nowrap\|''d'' − 1}}) (the case where {{nowrap\|''d'' ≤ 2}} is more complicated because of [[anyon]]s, etc.). As before, there are unitary representations which don't transform under the SE({{nowrap\|''d'' − 1}}) "translations" (the "standard" representations) and "continuous spin" representations.

			For massless [[spin-1/2\|spin-{{frac\|1\|2}} particles]], helicity is equivalent to the [[chirality (physics)\|chirality operator]] multiplied by <math>\scriptstyle \frac{1}{2}\hbar</math>.

			==See also==
			* [[Wigner's classification]]
			* [[Chirality (physics)\|Chirality]]
			* [[Pauli–Lubanski pseudovector]]

			{{DEFAULTSORT:Helicity (Particle Physics)}}
			[[Category:Particle physics]]
			[[Category:Quantum field theory]]

			{{particle-stub}}

63.228.127.70: wikipedia is not a place to pimp your product

2012-05-02T18:28:06Z

wikipedia is not a place to pimp your product

New page

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