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| − | {{DISPLAYTITLE:ΔR}}
| + | #REDIRECT [[Angular distance]] |
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| − | '''ΔR''' ('''delta R''') is the '''angular distance''' (or '''angular separation''') between two [[Object|objects]]. It tells how much two objects are moving in the same direction.
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| − | == At hadron colliders ==
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| − | At [[Hadron collider|hadron colliders]], the angular distance is usually defined in a way that is [[Longitudinal boost invariance|invariant under longitudinal boosts]]. This is achieved by using the [[pseudorapidity]] difference of the objects rather than an actual angle. In the [[transverse plane]], the momentum of the [[initial state]] is ([[Primordial kt|essentially]]) zero, so the [[azimuthal angle]] can be used directly.
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| − | == At lepton colliders ==
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| − | At [[Lepton collider|lepton colliders]], the vector angle between the object momenta may be used directly.
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