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I have a question regarding the results in this paper (and another which I will mention later)

http://arxiv.org/abs/hep-ph/0212199

Now, i'm not so concerned about the 'braney' bit, but more their definition of the cross section in Eqn. (46). They have included the usual (2j+1) term (which is present even in non-relativistic physics) but it seems to me it should be the full g(j) = (2j+1)/((2a+1)(2b+1)) where a and b are the spins of the incident particle and the target (in this case one of them can be zero as they consider a black hole target which is modeled as a classical potential, in some sense).

A similar definition seems to be used in this paper by R. Fabbri:

http://prd.aps.org/abstract/PRD/v12/i4/p933_1

in this case in Eqn. (34)

In both cases they consider spin 1 and so one would expect a factor of (2j+1)/3, or no?

Any help would be appreciated :\

Cheers!

-Z

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# Spin statistic terms in absorption cross section

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