arXiv subjects

Raji Ashenafi Mamade

Publications and source records attributed to Raji Ashenafi Mamade.

4 recordsLinked to original sources

arXiv2026

Universal quadratic field equations via homotopy algebras

We explain how the 'bar-cobar' construction for homotopy algebras reformulates the equations of motion of arbitrary gauge theories as gauge-covariant quadratic equations for an extended set of fields. The linear term of the new equations encodes the interactions of the original theory, while the quadratic term is universal. The extended fields include type-I multilocal fields, which depend on a set of coordinates and type-II multilocal fields, which depend on several sets of coordinates. The new equations of motion are the Maurer-Cartan equations of a differential graded associative algebra or Lie algebra. We show that every solution of the new equations is gauge equivalent to a solution with only type-I fields, that represents a solution of the original equations of motion. In string theory type-I fields are entangled states of the associated CFT, to be inserted across multiple punctures of a Riemann surface. General type-II states can also represent disconnected Riemann surfaces.

hep-th↗

arXiv2026

Gauge algebra and diffeomorphisms in string field theory

We consider the gauge algebra of closed string field theory with a focus on diffeomorphisms. This algebra contains off-shell information in two ways. The first way is geometric, through the choice of three-punctured sphere defining the three-string vertex. We establish that to leading order in derivatives the superstring algebra is universal: identical for any choice of vertex. For bosonic strings, however, some off-shell dependence remains for vertices that require symmetrization. Off-shell information also appears because field-dependent redefinition of the gauge parameters can alter the algebra. We analyze this dependence in the language of $L_\infty$ algebras, looking at the role of trivial gauge transformations in the efforts to demonstrate that standard diffeomorphisms are part of the string gauge symmetry.

hep-th↗

arXiv2025

Type II RR string fields and exotic diffeomorphisms

We study the theory of massless fields of type II strings arising from the string field theory that uses two string fields, a physical one and an extra one that allows the writing of an action, but whose degrees of freedom ultimately decouple. The mechanism allowing the description of the self-dual five-form of type IIB, anticipated by Sen, is used by the SFT to describe all Ramond-Ramond forms in type IIB and IIA in a manifestly duality-invariant way. We find explicit expressions for the leading terms in the gauge transformation of the RR fields and focus on diffeomorphisms, which are exotic for both the physical and the extra fields, perhaps as needed to describe propagating degrees of freedom that do not gravitate. The algebra of diffeomorphisms includes field-dependent structure constants and only closes on-shell, as predicted by the type II SFT gauge algebra.

hep-th↗

arXiv2025

Boundary terms in string field theory

We supplement the string field theory action with boundary terms to make its variational principle well-posed. Central to our considerations is the violation of the stress-energy tensor conservation in non-compact CFTs due to the boundary terms. This manifests as the failure of the cyclicity of the BRST operator, which encodes the target space integration by parts identities at the level of the worldsheet. Using this failure, we argue that the free closed string field theory action admits a well-posed variational principle upon including an additional boundary contribution. We explicitly work out the resulting action up to the massless level and show that it is related to the expansion of the low-energy effective string action endowed with the Gibbons-Hawking-York term on a flat background. We also discuss the structure of the boundary terms in the interacting theory.

hep-th↗