String Theory Demystified

Summary
204 String Theory Demystifi ed
THE |NS〉 ⊕ |R〉, |R〉 ⊕ |NS〉 SECTOR
The states in these sectors are superpartners of the dilaton and the graviton. Type II
A and type II B theories have the same states, but the states NS ⊗ R , R ⊗ NS
each have the same chirality in type II B theory and have the opposite chirality in
type II A theory. The states are
• The dilatino, the spin-1/2 superpartner of the dilaton, with 28 states.
• The gravitino, the spin-3/2 fermion which is the superpartner of the
graviton. For type II A theory the 2 gravitinos have opposite chirality.
THE |R〉 ⊕ |R〉 SECTOR
These are boson states formed from the tensor product of two Majorana-Weyl
spinors. In type II A theory the left and right states have opposite chirality,
while in type II B theory they have the same chirality. For type II A theory, there
are two states:
• A vector gauge fi eld
• A “3-form” gauge fi eld (see Relativity Demystifi ed for a description of
forms)
In type II B theory the states are
• A scalar fi eld
• A two-form gauge fi eld
• A four-form gauge fi eld
In this chapter, we have summarized the states of type II A and type II B string
theories, which are based on the R and NS sectors first introduced in Chap. 7.
Type II A theory consists of states that are tensor products of states with
opposite chiralities, while type II B theory consists of states that are tensor
products of states with the same chiralities. This results in different “particle”
states. These theories predict the existence of superpartners that have not yet
been observed in nature.