7,637 research outputs found
Massless spinning particle and null-string on : projective-space approach
Massless spinning particle and tensionless string models on
background in the projective-space realization are proposed as constrained
Hamiltonian systems. Various forms of particle and string Lagrangians are
derived and classical mechanics is studied including the Lax-type
representation of the equations of motion. After that transition to the quantum
theory is discussed. Analysis of potential anomalies in the tensionless string
model necessitates introduction of ghosts and BRST charge. It is shown that
quantum BRST charge is nilpotent for any if coordinate-momentum ordering
for the phase-space bosonic variables, Weyl ordering for the fermions and
() ordering for ghosts is chosen, while conformal
reparametrizations and space-time dilatations turn out to be anomalous for the
ordering in terms of positive and negative Fourier modes of the phase-space
variables and ghosts.Comment: 23 pages, v4: In the title and abstract added adjective 'Massless'.
In subsection 2.2 the material has been rearranged to streamline the
presentation and also a comment added to explain the notation. Minor
improvements of the text and further typos corrected. Version accepted for
publicatio
Conformal higher-spin symmetries in twistor string theory
It is shown that similarly to massless superparticle, classical global
symmetry of the Berkovits twistor string action is infinite-dimensional. We
identify its superalgebra, whose finite-dimensional subalgebra contains
superalgebra. In quantum theory this infinite-dimensional
symmetry breaks down to one.Comment: 20 pages, LaTeX. v2: section 3 undergone major revision, others -
minor improvements including correction of typos. Version accepted to Nuclear
Physics
Ambitwistors, oscillators and massless fields on
Positive energy unitary irreducible representations of can be
constructed with the aid of bosonic oscillators in (anti)fundamental
representation of that are closely related to Penrose
twistors. Starting with the correspondence between the doubleton
representations, homogeneous functions on projective twistor space and on-shell
generalized Weyl curvature spinors and their low-spin
counterparts, we study in the similar way the correspondence between the
massless representations, homogeneous functions on ambitwistor space and, via
the Penrose transform, with the gauge fields on Minkowski boundary of .
The possibilities of reconstructing massless fields on and some
applications are also discussed.Comment: 12 pages, LaTeX; v.3: comment and reference added, further typos
corrected, published versio
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