Physics Asked by IvanMartinez on October 6, 2020
Does the following functional derivative can be evaluated?
$$ frac{partial}{partial(partial_mu phi(x))} int d^4y F(y) partial_nupartial^nuphi(y)$$
I am trying to find the equations of motion of a classical field with a Lagrangian that has the form:
$$mathcal{L}(phi,partial_muphi)+int d^4y F(y) partial_nupartial^nuphi(y)$$
Is the conventional form of E-L equation valid here:
$$ frac{partial mathcal{L}}{partial(partial_mu phi(x))}- frac{partial mathcal{L}}{partial phi}=0$$
Or is a new form necessary due to the dependence on the second derivative inside the integral of the Lagrangian?
You can just partially integrate the double derivative to get $-partial_nu F partial^nu Phi$. Or use a definition for the functional derivative analog to the usual derivative, where you'd, in this case, replace $partial^nu Phi(y)$ by the delta-distribution of $delta(x-y)$.
Answered by drfk on October 6, 2020
Get help from others!
Recent Questions
Recent Answers
© 2024 TransWikia.com. All rights reserved. Sites we Love: PCI Database, UKBizDB, Menu Kuliner, Sharing RPP