arXiv subjects

Cesar Miquel-Espanya

Publications and source records attributed to Cesar Miquel-Espanya.

4 recordsLinked to original sources

arXiv2007

Twistor string as tensionless superstring

We give a brief review of the twistor string approach to supersymmetric Yang-Mills theories with an emphasis on the different formulations of (super)string models in supertwistor space and their superspace form. We discuss the classical equivalence among the Siegel closed twistor string and the Lorentz harmonics formulation of the (N=4) tensionless superstring, and notice the possible relation of the twistor string to the D=10 Green-Schwarz superstring action, as well as to models in the enlarged, tensorial superspaces that are relevant in higher spin theories.

hep-th↗

arXiv2006

Massive relativistic particle model with spin from free two-twistor dynamics and its quantization

We consider a relativistic particle model in an enlarged relativistic phase space M^{18} = (X_μ, P_μ, η_α, \oeta_\dalpha, σ_α, \osigma_\dalpha, e, ϕ), which is derived from the free two-twistor dynamics. The spin sector variables (η_α, \oeta_\dalpha, σ_α,\ osigma_\dalpha) satisfy two second class constraints and account for the relativistic spin structure, and the pair (e,ϕ) describes the electric charge sector. After introducing the Liouville one-form on M^{18}, derived by a non-linear transformation of the canonical Liouville one-form on the two-twistor space, we analyze the dynamics described by the first and second class constraints. We use a composite orthogonal basis in four-momentum space to obtain the scalars defining the invariant spin projections. The first-quantized theory provides a consistent set of wave equations, determining the mass, spin, invariant spin projection and electric charge of the relativistic particle. The wavefunction provides a generating functional for free, massive higher spin fields.

hep-th↗

arXiv2006

Superspace formulations of the (super)twistor string

The superspace formulation of the worldvolume action of twistor string models is considered. It is shown that for the Berkovits-Siegel closed twistor string such a formulation is provided by a N=4 twistor-like action of the tensionless superstring. A similar inverse twistor transform of the open twistor string model (Berkovits model) results in a dynamical system containing two copies of the D=4, N=4 superspace coordinate functions, one left-moving and one right-moving, that are glued by the boundary conditions. We also discuss possible candidates for a tensionful superstring action leading to the twistor string in the tensionless limit as well as multidimensional counterparts of twistor strings in the framework of both `standard' superspace and superspace enlarged by tensorial coordinates (tensorial superspaces), which constitute a natural framework for massless higher spin theories.

hep-th↗

arXiv2004

Spacetime scale-invariant super-p-brane actions on enlarged superspaces and the geometry of kappa-symmetry

We use the additional variables of suitably enlarged superspaces to write new actions for extended objects, with kappa-symmetry, in such a way that the tension emerges from them as an integration constant. Our actions correspond to the spacetime scale-invariant ones previously considered by Bergshoeff et al. once the worldvolume forms introduced there are reinterpreted in terms of fields associated with the coordinates of the enlarged superspaces. It is shown that the kappa-symmetry of the new actions is given by a certain type of right local transformations of the extended superspace groups. Further, we also show that the enlarged superspaces that allow for strictly invariant Wess-Zumino terms also lead to strict kappa-invariance i.e., the Lagrangian itself (not only the action) is both supersymmetry- and kappa-invariant.

hep-th↗