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String theory does predict massless particles associated with moduli fields that haven't been observed. Would gravitons be one of these particles?

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  • $\begingroup$ No, the graviton emerges as one of the modes of the string. The massless particles associated with the moduli fields are completely different. $\endgroup$ – John Rennie Oct 21 '17 at 18:53
  • $\begingroup$ Thank you! And would these particles exist in any possible universe in string theory's landscape? $\endgroup$ – user138802 Oct 21 '17 at 19:15
  • $\begingroup$ If you believe in the string landscape then the moduli have discrete values and cannot vary continuously. That means there are no massless particles associated with the moduli fields. Any one universe in the landscape has a specific set of values for all the moduli. The graviton exists in all universes of course. $\endgroup$ – John Rennie Oct 21 '17 at 19:28
  • $\begingroup$ And would these values be different in all these universes? $\endgroup$ – user138802 Oct 22 '17 at 12:30
  • $\begingroup$ I mean would these universes have diffeent values between them? $\endgroup$ – user138802 Oct 22 '17 at 12:49
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I'm not an expert in string theory, but I believe those massless particles are all scalars (i.e. spin 0), and thus immediately not candidates for the graviton (which couples to the stress-energy tensor and so must be spin 2).

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  • $\begingroup$ Thank you! And would these particles exist in any possible universe in string theory's landscape? $\endgroup$ – user138802 Oct 21 '17 at 19:16

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