412 research outputs found
Canonical Realization of (2+1)-dimensional Bondi-Metzner-Sachs symmetry
We construct canonical realizations of the algebra as
symmetry algebras of a free Klein-Gordon (KG) field in dimensions, for
both the massive and massless case. We consider two types of realizations, one
on-shell, written in terms of the Fourier modes of the scalar field, and the
other one off-shell with non-local transformations written in terms of the KG
field and its momenta. These realizations contain both supertranslations and
superrotations, for which we construct the corresponding Noether charges.Comment: Version accepted for publication in PRD. Expanded title and expanded
discussion about superrotations in the massive cas
Extended Galilean symmetries of non-relativistic strings
We consider two non-relativistic strings and their Galilean symmetries. These strings are obtained as the two possible non-relativistic (NR) limits of a relativistic string. One of them is non-vibrating and represents a continuum of non-relativistic massless particles, and the other one is a non-relativistic vibrating string. For both cases we write the generator of the most general point transformation and impose the condition of Noether symmetry. As a result we obtain two sets of non-relativistic Killing equations for the vector fields that generate the symmetry transformations. Solving these equations shows that NR strings exhibit two extended, infinite dimensional space-time symmetries which contain, as a subset, the Galilean symmetries. For each case, we compute the associated conserved charges and discuss the existence of non-central extensions.Postprint (author's final draft
Dynamical sectors for a spinning particle in AdS_3
We consider the dynamics of the motion of a particle of mass M and spin J in
AdS_3. The study reveals the presence of different dynamical sectors depending
on the relative values of M, J and the AdS_3 radius R. For the subcritical M^2
R^2-J^2 >0 and supercritical M^2 R^2-J^2<0 cases, it is seen that the equations
of motion give the geodesics of AdS_3. For the critical case M^2R^2=J^2 there
exist extra gauge transformations which further reduce the physical degrees of
freedom, and the motion corresponds to the geodesics of AdS_2. This result
should be useful in the holographic interpretation of the entanglement entropy
for 2d conformal field theories with gravitational anomalies.Comment: 12 pages, 1 figure, Some comments, references and formulas are adde
Space-time Schr\"odinger symmetries of a post-Galilean particle
We study the space-time symmetries of the actions obtained by expanding the
action for a massive free relativistic particle around the Galilean action. We
obtain all the point space-time symmetries of the post-Galilean actions by
working in canonical space. We also construct an infinite collection of
generalized Schr\"odinger algebras parameterized by an integer , with
corresponding to the standard Schr\"odinger algebra. We discuss the
Schr\"odinger equations associated to these algebras, their solutions and
projective phases.Comment: Version accepted for publication in JHE
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