Relativistic angular momentum and cyclic coordinates

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SUMMARY

The discussion centers on the calculation of relativistic angular momentum using the Lagrangian for a particle in a central potential, defined as L = -m0 c²/γ - V(r). The participant initially expressed confusion regarding the derivative of the Lagrangian with respect to the angular velocity, dL/d(dot{theta}), which should yield conserved angular momentum. Upon reevaluation, they confirmed that the correct expression for angular momentum is ∂L/∂(dot{theta}) = γ m0 r² dot{theta}, indicating that their initial concerns were unfounded.

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  • Knowledge of the Lorentz factor, γ, and its implications in relativistic equations
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maverick_starstrider
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I'm getting myself confused here. If my relativistic Lagrangian for a particle in a central potentai is

L = \frac{-m_0 c^2}{\gamma} - V(r)

should

\frac{d L}{d \dot{\theta}}

not give me the angular momentum (which is conserved)? Instead I get

\frac{d L}{d \dot{\theta}} = -4 m v r^2 \dot{\theta}\gamma
 
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Anyone?
 
L = - {m_0}{c^2}\sqrt {1 - \frac{{{{\dot r}^2} + {r^2}{{\dot \theta }^2}}}{{{c^2}}}} - V\left( r \right)

so

\frac{{\partial L}}{{\partial \dot \theta }} = \gamma {m_0}{r^2}\dot \theta

What's the problem?
 
Absolutely nothing apparently. I just did it again this morning and got the right answer. Sorry for the time waste.
 

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