Contents

• 1 Introduction
• 2 The free theory: Lagrangian, gauge symmetries and BRST differential
• 3 Strategy
• 4 Standard results
• 5 Computation of first-order deformation
• 6 Computation of higher-order deformations
• 7 The coupled theory: Lagrangian and gauge structure
• 8 Some solutions to the consistency equations
• 9 Conclusion
• A. No-go result for $I=5$ in $a^{\mathrm {int}}$
• B. No-go result for $I=4$ in $a^{\mathrm {int}}$
• C. No-go result for $I=3$ in $a^{\mathrm {int}}$
• D. No-go result for $I=0$ in $a^{\mathrm {int}}$
• E. Notations from section 6
• F. Deformed gauge structure
• Bibliography