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Luca Mezincescu

Publications and source records attributed to Luca Mezincescu.

At least 19 recordsLinked to original sources
arXiv2024

Hamiltonian birefringence and Born-Infeld limits

Using Hamiltonian methods, we find six relativistic theories of nonlinear electrodynamics for which plane wave perturbations about a constant uniform background are not birefringent. All have the same conformal strong-field limit to Bialynicki-Birula (BB) electrodynamics, but only four avoid superluminal propagation: Born-Infeld (BI), its non-conformal ``extreme'' limits (electric and magnetic) and the conformal BB limit. The quadratic dispersion relation of BI is shown to degenerate in the extreme limits to a pair of linear relations, which become identical in the BB limit.

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arXiv2022

On chiral bosons in 2D and 6D

In the Hamiltonian formulation of chiral 2k-form electrodynamics, the 2k-form potential on the (4k+1)-space is defined up to the addition of either (i) a closed $2k$-form or (ii) an exact 2k-form, depending on the choice of chirality constraint. Case (i) is realized by the Floreanini-Jackiw 2D chiral boson (for k=0) and its Henneaux-Teitelboim generalisation to k>0. For all k, but focusing on the 6D case, we present a simple Lorentz-invariant Hamiltonian model that realizes case (ii), and we derive it from Siegel's manifestly Lorentz invariant Lagrangian formulation.

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arXiv2021

Global Symmetries of Quaternion-K$\bf \ddot{a}$hler ${\cal N}=4$ Supersymmetric Mechanics

We analyze the global symmetries of ${\cal N}=4$ supersymmetric mechanics involving $4n$-dimensional Quaternion-Kähler (QK) $1D$ sigma models on projective spaces $\mathbb{H}{\rm H}^n$ and $\mathbb{H}{\rm P}^n$ as the bosonic core. All Noether charges associated with global worldline symmetries are shown to vanish as a result of equations of motion, which implies that we deal with a severely constrained hamiltonian system. The complete hamiltonian analysis of the bosonic sector is performed.

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arXiv2019

DBI in the IR

The IR limit of a planar static D3-brane in AdS5 x S5 is a tensionless D3-brane at the AdS horizon, with dynamics governed by a strong-field limit of the Dirac-Born-Infeld action analogous to that found from the Born-Infeld action by Bialynicki-Birula. As in that case, the field equations are those of an interacting 4D conformal invariant field theory with an Sl(2;R) electromagnetic duality invariance, but the D3-brane origin makes these properties manifest. We also find an Sl(2;R)-invariant action for these equations.

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arXiv2018

Quaternion-Kähler N=4 Supersymmetric Mechanics

Using the N=4, 1D harmonic superspace approach, we construct a new type of N=4 supersymmetric mechanics involving 4n-dimensional Quaternion-Kähler (QK) 1D sigma models as the bosonic core. The basic ingredients of our construction are {\it local} N=4, 1D supersymmetry realized by the appropriate transformations in 1D harmonic superspace, the general N=4, 1D superfield vielbein and a set of 2(n+1) analytic "matter" superfields representing (n+1) off-shell supermultiplets (4, 4, 0). Both superfield and component actions are given for the simplest QK models with the manifolds \mathbb{H}H^n = Sp(1,n)/[Sp(1) x Sp(n)] and \mathbb{H}P^n = Sp(1+n)/[Sp(1) x Sp(n)] as the bosonic targets. For the general case the relevant superfield action and constraints on the (4, 4, 0) "matter" superfields are presented. Further generalizations are briefly discussed.

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arXiv2017

Pauli-Lubanski, Supertwistors, and the Superspinning Particle

We present a novel construction of the super-Pauli-Lubanski pseudo-vector for 4D supersymmetry and show how it arises naturally from the spin-shell constraints in the supertwistor formulation of superparticle dynamics. We illustrate this result in the context of a simple classical action for a "superspinning particle" of superspin 1/2. We then use an Sl(2;K)-spinor formalism for K=R,C,H to unify our 4D results with previous results for 3D and 6D (super)Pauli-Lubanski tensors.

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arXiv2017

Tachyons in the Galilean limit

The Souriau massless Galilean particle of "colour" $k$ and spin $s$ is shown to be the Galilean limit of the Souriau tachyon of mass $m = ik$ and spin $s$. We compare and contrast this result with the recent Galilean limit of the Nambu-Goto string and the Green-Schwarz superstring.

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arXiv2016

Worldline CPT and massless supermultiplets

The action for a massless particle in 4D Minkowski space has a worldline time-reversing symmetry corresponding to CPT invariance of the quantum theory. The analogous symmetry of the N-extended superparticle is shown to be anomalous when N is odd, in the supertwistor formalism this is because a CPT-violating worldline-Chern-Simons term is needed to preserve the chiral U(1) gauge invariance. This accords with the fact that no massless N=1 super-Poincaré irrep is CPT-self-conjugate. There is a CPT self-conjugate supermultiplet when N is even, but it has $2^{N+1}$ states when N/2 is odd (e.g. the N=2 hypermultiplet) in contrast to just $2^N$ when N/2 is even (e.g. the N=4 Maxwell supermultiplet). This is shown to follow from a Kramers degeneracy of the superparticle state space when N/2 is odd.

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arXiv2015

Twistors and the massive spinning particle

Gauge-invariant twistor variables are found for the massive spinning particle with N-extended local worldline supersymmetry, in spacetime dimensions D=3,4,6. The twistor action is manifestly Lorentz invariant but the anticommuting spin variables appear exactly as in the non-relativistic limit. This allows a simple confirmation that the quantum N=2 spinning particle has either spin one or spin zero, and that N>2 is quantum inconsistent for D=4,6.

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arXiv2014

Supertwistors and massive particles

In the (super)twistor formulation of massless (super)particle mechanics, the mass-shell constraint is replaced by a "spin-shell" constraint from which the spin content can be read off. We extend this formalism to massive (super)particles (with N-extended spacetime supersymmetry) in three and four space-time dimensions, explaining how the spin-shell constraints are related to spin, and we use it to prove equivalence of the massive N=1 and BPS-saturated N=2 superparticle actions. We also find the supertwistor form of the action for "spinning particles" with N-extended worldline supersymmetry, massless in four dimensions and massive in three dimensions, and we show how this simplifies special features of the N=2 case.

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arXiv2014

All Superparticles are BPS

The generic action for an N-extended superparticle in D-dimensional Minkowski spacetime is shown to have "hidden" supersymmetries (related by "dualities" to the manifest supersymmetries) such that the full supersymmetry algebra is BPS-saturated; the exceptions (which include, trivially, the massless case) are those for which the manifest supersymmetry algebra is already BPS-saturated. Moreover, it is shown that any "non-BPS" superparticle action is a gauge-fixed version of the "BPS" superparticle action for which all supersymmetries are manifest. An example is the N=1 massive D=10 superparticle, which actually has N=2 supersymmetry and is equivalent to the action for a D0-brane of IIA superstring theory.

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arXiv2013

Equivalence of 3D Spinning String and Superstring

We perform a light-cone gauge quantization of the Ramond closed spinning string in three spacetime dimensions (3D). The spectrum is Lorentz invariant and identical to that of the 3D Green-Schwarz closed superstring with ${\cal N}=2$ space-time supersymmetry, quantized in light-cone gauge.

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arXiv2011

Quantum 3D Superstrings

The classical Green-Schwarz superstring action, with N=1 or N=2 spacetime supersymmetry, exists for spacetime dimensions D=3,4,6,10, but quantization in the light-cone gauge breaks Lorentz invariance unless either D=10, which leads to critical superstring theory, or D=3. We give details of results presented previously for the bosonic and N=1 closed 3D (super)strings and extend them to the N=2 3D superstring. In all cases, the spectrum is parity-invariant and contains anyons of irrational spin.

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arXiv2011

The Quantum 3D Superparticle

The minimal (${\cal N}=1$) superparticle in three spacetime dimensions (3D) is quantized. For non-zero mass it describes a spin-1/4 semion supermultiplet of "relativistic helicities" (-1/4, 1/4). The addition of a parity-violating Lorentz-Wess-Zumino term shifts this to $(β-1/4,β+1/4)$ for arbitrary $β$. For zero mass, in which case spin is not defined, the quantum superparticle describes a supermultiplet of one boson and one fermion.

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arXiv2010

Semionic Supersymmetric Solitons

The Bogomolnyi vortex of the N=2 supersymmetric abelian-Higgs model in 2+1 dimensions is shown to be a ``semion'' of spin 1/4. Specifically, the effective superparticle action for one vortex is shown to describe, upon quantization, a parity self-dual centrally-charged `short' supermultiplet of ``relativistic helicities'' (-1/4,-1/4, 1/4,1/4).

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arXiv2010

Anyons from Strings

The Nambu-Goto string in a 3-dimensional (3D) Minkowski spacetime is quantized preserving Lorentz invariance and parity. The spectrum of massive states contains anyons. An ambiguity in the ground state energy is resolved by the 3D N=1 Green-Schwarz superstring, which has massless ground states describing a dilaton and dilatino, and first-excited states of spin 1/4.

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arXiv2010

Generalized N = 2 Super Landau Models

We generalize previous results for the superplane Landau model to exhibit an explicit worldline N = 2 supersymmetry for an arbitrary magnetic field on any two-dimensional manifold. Starting from an off-shell N = 2 superfield formalism, we discuss the quantization procedure in the general case characterized by two independent potentials on the manifold and show that the relevant Hamiltonians are factorizable. In the restricted case when both the Gauss curvature and the magnetic field are constant over the manifold and, as a consequence, the underlying potentials are related, the Hamiltonians admit infinite series of factorization chains implying the integrability of the associated systems. We explicitly determine the spectrum and eigenvectors for the particular model with CP^1 as the bosonic manifold.

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