A First Course in String Theory

14.3 Massive level in the open superstring

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**How come R sector has a factor 16 while NS sector has not?**

Equation (14.66):

Equation (14.68):

p.319 “The overall multiplicative factor appears because each combination of oscillators gives rise to 16 states by acting on each of the available ground states.”

p.319 “We note that the R coefficients are actually double the corresponding NS coefficients. This is not a coincidence, as we will see in the following section.”

p.320 “We have seen that the Ramond sector has world-sheet supersymmetry: there are equal numbers of fermionic and bosonic states at each mass level.”

**With the factor 16, how come the R coefficients are only double, but not 16 times as big as the corresponding NS coefficients?**

It is caused by the difference of and .

— Me@2015.10.06 08:23 AM

2015.10.06 Tuesday (c) All rights reserved by ACHK