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Nambu-Goto String

  1. Apr 5, 2010 #1
    Hi there,

    I recently read about the construction of the Nambu-Goto action by looking at the proper area of the world-sheet. However, when one varies the action with an arbitrary space-time coordinate (here I treat it in Minkowski space-time X^(\mu)), there appears three terms and some of them would go to zero.

    What I don't understand is why is that

    (i) The momentum density running along the string P^(\mu)_(\sigma) at the open string endpoints \sigma (0, \pi) is zero?

    (ii) Why is it that the momentum density transverse to the string, i.e. P^(\mu)_(\tau) \neq 0?

    Has this got something to do with the conservation law, that energy is conserved?

  2. jcsd
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