Heterotic string theory

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This article is about string theory. For heterosis in biology, see Heterosis.
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In

first superstring revolution
.

Overview

In string theory, the left-moving and the right-moving excitations of strings are completely decoupled,[4] and it is possible to construct a string theory whose left-moving (counter-clockwise) excitations are treated as a bosonic string propagating in D = 26 dimensions, while the right-moving (clockwise) excitations are treated as a superstring in D = 10 dimensions.

The mismatched 16 dimensions must be compactified on an even,

SO(32) (the HO string) while the other is E8 × E8 (the HE string).[5]

These two gauge groups also turned out to be the only two anomaly-free gauge groups that can be coupled to the N = 1 supergravity in 10 dimensions. (Although not realized for quite some time, U(1)496 and E8 × U(1)248 are anomalous.[6])

Every heterotic string must be a

boundary conditions
that would relate the left-moving and the right-moving excitations because they have a different character.

String duality

open strings; this relation is called S-duality. The HO and HE theories are also related by T-duality
.

Because the various superstring theories were shown to be related by dualities, it was proposed that each type of string was a different limit of a single underlying theory called M-theory.

References

  1. ISBN 9780521633048
    .
  2. PMID 10031535
    .
  3. ^ Dennis Overbye (2004-12-07). "String theory, at 20, explains it all (or not)". The New York Times. Retrieved 2020-03-15.
  4. OCLC 607562796
    .
  5. ^ Joseph Polchinski (1998). String Theory: Volume 2, p. 45.
  6. S2CID 13916249
    .
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