100 research outputs found
The quintic interaction vertex in light-cone gravity
No full textAbstractWe consider pure gravity in light-cone gauge and derive the complete quintic interaction vertex. Up to quartic order, the Kawai–Lewellen–Tye (KLT) relations can be made manifest at the level of the Einstein–Hilbert Lagrangian. The quintic interaction vertex represents an essential first step in further extending the off-shell validity of the KLT relations to higher order vertices
Theories with Memory
No full textDimensionally reduced supersymmetric theories retain a great deal of information regarding their higher dimensional origins. In superspace, this "memory" allows us to restore the action governing a reduced theory to that describing its higher-dimensional progenitor. We illustrate this by restoring four-dimensional N=4 Yang-Mills to its six-dimensional parent, N=(1,1) Yang-Mills. Supersymmetric truncation is introduced into this framework and used to obtain the N=1 action in six dimensions. We work in light-cone superspace, dealing exclusively with physical degrees of freedom
Yang-Mills theories and quadratic forms
No full textAbstract: We show that the Hamiltonian of (N=1, d = 10) super Yang-Mills can be expressed as a quadratic form in a very similar manner to that of the (N=4, d = 4) theory. We find a similar quadratic form structure for pure Yang-Mills theory but this feature, in the non-supersymmetric case, seems to be unique to four dimensions. We discuss some consequences of this feature. © 2015, The Author(s)
GRAVITY AND YANG–MILLS THEORY
No full text Three of the four forces of Nature are described by quantum Yang–Mills theories with remarkable precision. The fourth force, gravity, is described classically by the Einstein–Hilbert theory. There appears to be an inherent incompatibility between quantum mechanics and the Einstein–Hilbert theory which prevents us from developing a consistent quantum theory of gravity. The Einstein–Hilbert theory is therefore believed to differ greatly from Yang–Mills theory (which does have a sensible quantum mechanical description). It is therefore very surprising that these two theories actually share close perturbative ties. This essay focuses on these ties between Yang–Mills theory and the Einstein–Hilbert theory. We discuss the origin of these ties and their implications for a quantum theory of gravity. </jats:p
Light-cone gravity in dS4
No full textAbstractWe derive a closed form expression for the light-cone Lagrangian describing pure gravity on a four-dimensional de Sitter background. We provide a perturbative expansion of this Lagrangian to cubic order in the fields
Factorization of cubic vertices involving three different higher spin fields
No full textAbstractWe derive a class of cubic interaction vertices for three higher spin fields, with integer spins λ1, λ2, λ3, by closing commutators of the Poincaré algebra in four-dimensional flat spacetime. We find that these vertices exhibit an interesting factorization property which allows us to identify off-shell perturbative relations between them
BMS symmetry in gravity: Front form versus Instant form
No full textIn General Relativity, the allowed set of diffeomorphisms or gauge
transformations at asymptotic infinity forms the BMS group, an
infinite-dimensional extension of the Poincar\'e group. We focus on the
structure of the BMS group in two distinct forms of Hamiltonian dynamics - the
instant and front forms. Both similarities and differences in these two forms
are examined while emphasising the role of non-covariant approaches to
symmetries in gravity.Comment: 9 pages and 3 figures, Honorable Mention - Gravity Research
Foundation 202
Exceptional symmetries in light-cone superspace
No full textAbstract We construct maximal supergravity in five-dimensions by ‘oxidizing’ the four-dimensional N = 8 theory. The relevant symmetries, the unitary symplectic group USp(8) and the exceptional group E 6, are both presented in light-cone superspace and their connections with SU(8) and E 7 highlighted. We explain a procedure to derive higher-point interaction vertices in both the 4- and 5-dimensional supergravity theories using exclusively the exceptional symmetries. Specific forms for the quartic and quintic interaction vertices in light-cone superspace are derived
BMS algebra from residual gauge invariance in light-cone gravity
No full textWe analyze the residual gauge freedom in gravity, in four dimensions, in the light-cone gauge, in a formulation where unphysical fields are integrated out. By checking the invariance of the light-cone Hamiltonian, we obtain a set of residual gauge transformations, which satisfy the BMS algebra realized on the two physical fields in the theory. Hence, the BMS algebra appears as a consequence of residual gauge invariance in the bulk and not just at the asymptotic boundary. We highlight the key features of the light-cone BMS algebra and discuss its connection with the quadratic form structure of the Hamiltonian
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