Symmetry-deforming interactions of chiral p-forms

No-go theorems on gauge-symmetry-deforming interactions of chiral p-forms are reviewed. We consider the explicit case of p=4, D=10 and show that the only symmetry-deforming consistent vertex for a system of one chiral 4-form and two 2-forms is the one that occurs in the type II B supergravity Lagrangian.Comment: 7 pages, tiny typo corrections, based on a talk given by M. H. at the conference "Constrained Dynamics and Quantum Gravity " held in Villasimius (Sardinia), September 13-17 1999, to appear in the proceedings of the meeting (Nucl. Phys. B Proc. Suppl.

On The Gauge-Fixed BRST Cohomology

A crucial property of the standard antifield-BRST cohomology at non negative ghost number is that any cohomological class is completely determined by its antifield independent part. In particular, a BRST cocycle that vanishes when the antifields are set equal to zero is necessarily exact.\ \ This property, which follows from the standard theorems of homological perturbation theory, holds not only in the algebra of local functions, but also in the space of local functionals. The present paper stresses how important it is that the antifields in question be the usual antifields associated with the gauge invariant description. By means of explicit counterexamples drawn from the free Maxwell-Klein-Gordon system, we show that the property does not hold, in the case of local functionals, if one replaces the antifields of the gauge invariant description by new antifields adapted to the gauge fixation. In terms of these new antifields, it is not true that a local functional weakly annihilated by the gauge-fixed BRST generator determines a BRST cocycle; nor that a BRST cocycle which vanishes when the antifields are set equal to zero is necessarily exact.Comment: 14 pages Latex fil

Uniqueness of the Freedman-Townsend Interaction Vertex For Two-Form Gauge Fields

Let $B_{\mu \nu }^a$ ($a=1,...,N$) be a system of $N$ free two-form gauge fields, with field strengths $H_{\mu \nu \rho }^a = 3 \partial _{[\mu }B_{\nu \rho ]}^a$ and free action $S_0$ equal to $(-1/12)\int d^nx\ g_{ab}H_{\mu \nu \rho }^aH^{b\mu \nu \rho }$ ($n\geq 4$). It is shown that in $n>4$ dimensions, the only consistent local interactions that can be added to the free action are given by functions of the field strength components and their derivatives (and the Chern-Simons forms in $5$ mod $3$ dimensions). These interactions do not modify the gauge invariance $B_{\mu \nu }^a\rightarrow B_{\mu \nu }^a+\partial _{[\mu }\Lambda _{\nu ]}$ of the free theory. By contrast, there exist in $n=4$ dimensions consistent interactions that deform the gauge symmetry of the free theory in a non trivial way. These consistent interactions are uniquely given by the well-known Freedman-Townsend vertex. The method of proof uses the cohomological techniques developed recently in the Yang-Mills context to establish theorems on the structure of renormalized gauge-invariant operators.Comment: 12 pages Latex fil

Ghosts of ghosts for second class constraints

When one uses the Dirac bracket, second class constraints become first class. Hence, they are amenable to the BRST treatment characteristic of ordinary first class constraints. This observation is the starting point of a recent investigation by Batalin and Tyutin, in which all the constraints are put on the same footing. However, because second class constraints identically vanish as operators in the quantum theory, they are quantum-mechanically reducible and require therefore ghosts of ghosts. Otherwise, the BRST cohomology would not yield the correct physical spectrum. We discuss how to incorporate this feature in the formalism and show that it leads to an infinite tower of ghosts of ghosts. An alternative treatment, in which the brackets of the ghosts are modified, is also mentioned.Comment: 7 pages in LaTex, ULB-PMIF/93-0

Consistent Interactions Between Gauge Fields: The Cohomological Approach

The cohomological approach to the problem of consistent interactions between fields with a gauge freedom is reviewed. The role played by the BRST symmetry is explained. Applications to massless vector fields and 2-form gauge fields are surveyed.Comment: late

Geometric Interpretation of the Quantum Master Equation in the BRST--anti-BRST Formalism

The geometric interpretation of the antibracket formalism given by Witten is extended to cover the anti-BRST symmetry. This enables one to formulate the quantum master equation for the BRST--anti-BRST formalism in terms of integration theory over a supermanifold. A proof of the equivalence of the standard antibracket formalism with the antibracket formalism for the BRST--anti-BRST symmetry is also given.Comment: 12 page

Spacetime locality of the antifield formalism : a "mise au point"

Some general techniques and theorems on the spacetime locality of the antifield formalism are illustrated in the familiar cases of the free scalar field, electromagnetism and Yang-Mills theory. The analysis explicitly shows that recent criticisms of the usual approach to dealing with locality are ill-founded.Comment: 15 pages in LaTeX, ULB-PMIF-93/0

Homological Algebra and Yang-Mills Theory

The antifield-BRST formalism and the various cohomologies associated with it are surveyed and illustrated in the context of Yang-Mills gauge theory. In particular, the central role played by the Koszul-Tate resolution and its relation to the characteristic cohomology are stressed.Comment: 20 pages in LaTe

Gauge Invariance for Generally Covariant Systems

Previous analyses on the gauge invariance of the action for a generally covariant system are generalized. It is shown that if the action principle is properly improved, there is as much gauge freedom at the endpoints for an arbitrary gauge system as there is for a system with ``internal'' gauge symmetries. The key point is to correctly identify the boundary conditions for the allowed histories and to include the appropriate end-point contribution in the action. The path integral is then discussed. It is proved that by employing the improved action, one can use time-independent canonical gauges even in the case of generally covariant theories. From the point of view of the action and the path integral, there is thus no conceptual difference between general covariance and ``ordinary gauge invariance''. The discussion is illustrated in the case of the point particle, for which various canonical gauges are considered.Comment: 41 pages, ULB-PMIF-92-0