### Abstract

We investigate in detail the critical N = 2 fermionic string with and without a global Z_{2} twist. An analysis of BRST cohomology shows that twisted sectors contain massless 'spacetime' fermions which are non-local with respect to the standard massless boson. However, two distinct GSO projections exist, one (untwisted) retaining merely the usual boson and its spectral-flow partner, the other (twisted) yielding two fermions and one boson, on the massless level. The corresponding chiral BRST-invariant vertex operators are constructed in certain pictures, and their fusion and picture-changing are investigated, including the construction of inverse picture-changing operators. The N = 2 'spacetime supersymmetry' generators are null operators, since the twisted massless states fail to interact. The untwisted three- and four-point functions are recalculated at tree-level.

Original language | English |
---|---|

Pages (from-to) | 373-409 |

Number of pages | 37 |

Journal | Nuclear Physics, Section B |

Volume | 438 |

Issue number | 1-2 |

DOIs | |

Publication status | Published - 27 Mar 1995 |

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### ASJC Scopus subject areas

- Nuclear and High Energy Physics

### Cite this

*Nuclear Physics, Section B*,

*438*(1-2), 373-409. https://doi.org/10.1016/0550-3213(94)00536-N

**The GSO projection, BRST cohomology and picture-changing in N = 2 string theory.** / Bischoff, Jan; Ketov, Sergei V.; Lechtenfeld, Olaf.

Research output: Contribution to journal › Article

*Nuclear Physics, Section B*, vol. 438, no. 1-2, pp. 373-409. https://doi.org/10.1016/0550-3213(94)00536-N

}

TY - JOUR

T1 - The GSO projection, BRST cohomology and picture-changing in N = 2 string theory

AU - Bischoff, Jan

AU - Ketov, Sergei V.

AU - Lechtenfeld, Olaf

PY - 1995/3/27

Y1 - 1995/3/27

N2 - We investigate in detail the critical N = 2 fermionic string with and without a global Z2 twist. An analysis of BRST cohomology shows that twisted sectors contain massless 'spacetime' fermions which are non-local with respect to the standard massless boson. However, two distinct GSO projections exist, one (untwisted) retaining merely the usual boson and its spectral-flow partner, the other (twisted) yielding two fermions and one boson, on the massless level. The corresponding chiral BRST-invariant vertex operators are constructed in certain pictures, and their fusion and picture-changing are investigated, including the construction of inverse picture-changing operators. The N = 2 'spacetime supersymmetry' generators are null operators, since the twisted massless states fail to interact. The untwisted three- and four-point functions are recalculated at tree-level.

AB - We investigate in detail the critical N = 2 fermionic string with and without a global Z2 twist. An analysis of BRST cohomology shows that twisted sectors contain massless 'spacetime' fermions which are non-local with respect to the standard massless boson. However, two distinct GSO projections exist, one (untwisted) retaining merely the usual boson and its spectral-flow partner, the other (twisted) yielding two fermions and one boson, on the massless level. The corresponding chiral BRST-invariant vertex operators are constructed in certain pictures, and their fusion and picture-changing are investigated, including the construction of inverse picture-changing operators. The N = 2 'spacetime supersymmetry' generators are null operators, since the twisted massless states fail to interact. The untwisted three- and four-point functions are recalculated at tree-level.

UR - http://www.scopus.com/inward/record.url?scp=0001470549&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0001470549&partnerID=8YFLogxK

U2 - 10.1016/0550-3213(94)00536-N

DO - 10.1016/0550-3213(94)00536-N

M3 - Article

AN - SCOPUS:0001470549

VL - 438

SP - 373

EP - 409

JO - Nuclear Physics B

JF - Nuclear Physics B

SN - 0550-3213

IS - 1-2

ER -