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P. Maraner

Publications and source records attributed to P. Maraner.

10 recordsLinked to original sources
arXiv2001

Dimensional Reduction by a Two-Form (another alternative to compactification)

It is shown that the local coupling of a higher dimensional graviton to a closed degenerate two-form produces dimensional reduction by spontaneous breakdown of extra-dimensional translational symmetry. Four dimensional Poincaré invariance emerges as residual symmetry. As a specific example, a six dimensional geometry coupled to a closed rank 2 two-form yields the `ground state' $$ds^2={\rm e}^{-|ξ|^2/4l^2}η_{μν}dx^μdx^ν+δ_{ij} dξ^i dξ^j$$ with $l$ a fundamental length scale. At low energies, space-time reduces to four observable dimensions and general relativistic gravity is reproduced.

hep-th↗
arXiv2000

Fermion Quantum Numbers and Families Replication from an Extension of Space-Time Relativity

The fermionic sector of the Standard Model of Elementary Particles emerges as the low energy limit of a single fermionic field freely propagating in a higher dimensional background. The local geometrical framework is obtained by enforcing at a space-time level the whole gauge group SO(1,3) x U(1) x SU(2) x SU(3) associated to fundamental interactions; equivalently, by assuming that internal gauge transformations are indeed local space-time transformations. The geometry naturally embodies freedoms corresponding to gravitational and non-gravitational gauge fields. As a consequence of the fact that the structural group is in part unitary, the motion of test particles gets automatically squeezed on an effective 1+3 space-time. Dimensional reduction takes place without compactification. In close analogy to the special relativistic mass-energy relation, the theory associates to every elementary particle an intrinsic energy presumably of the order of the Planck scale. The theory predicts the existence of a right-handed component of the neutrino and indicates the possibility of an extra U(1) gauge interaction.

hep-th↗
arXiv1998

Effective Dynamics on a Line

The effective classical/quantum dynamics of a particle constrained on a closed line embedded in a higher dimensional configuration space is analyzed. By considering explicit examples it is shown how different reduction mechanisms produce unequivalent dynamical behaviors. The relation with a formal treatment of the constraint is discussed. While classically it is always possible to strictly enforce the constraint by setting to zero the energy stored in the motion normal to the constraint surface, the quantum description is far more sensitive to the reduction mechanism. Not only quantum dynamics is plagued by the usual ambiguities inherent to the quantization procedure, but also in some cases the constraint's equations do not contain all the necessary information to reconstruct the effective motion.

hep-th↗
arXiv1998

Charged Particles in a 2+1 Curved Background

The coupling to a 2+1 background geometry of a quantized charged test particle in a strong magnetic field is analyzed. Canonical operators adapting to the fast and slow freedoms produce a natural expansion in the inverse square root of the magnetic field strength. The fast freedom is solved to the second order. At any given time, space is parameterized by a couple of conjugate operators and effectively behaves as the `phase space' of the slow freedom. The slow Hamiltonian depends on the magnetic field norm, its covariant derivatives, the scalar curvature and presents a peculiar coupling with the spin-connection.

hep-th↗
arXiv1996

Dynamics as Shadow of Phase Space Geometry

Starting with the generally well accepted opinion that quantizing an arbitrary Hamiltonian system involves picking out some additional structure on the classical phase space (the {\sl shadow} of quantum mechanics in the classical theory), we describe classical as well as quantum dynamics as a purely geometrical effect by introducing a {\sl phase space metric structure}. This produces an ${\cal O}(\hbar)$ modification of the classical equations of motion reducing at the same time the quantization of an arbitrary Hamiltonian system to standard procedures. Our analysis is carried out in analogy with the adiabatic motion of a charged particle in a curved background (the additional metric structure) under the influence of a universal magnetic field (the classical symplectic structure). This allows one to picture dynamics in an unusual way, and reveals a dynamical mechanism that produces the selection of the right set of physical quantum states.

quant-ph↗
arXiv1996

Quantum Charged Spinning Particles in a Strong Magnetic Field (a Quantal Guiding Center Theory)

A quantal guiding center theory allowing to systematically study the separation of the different time scale behaviours of a quantum charged spinning particle moving in an external inhomogeneous magnetic filed is presented. A suitable set of operators adapting to the canonical structure of the problem and generalizing the kinematical momenta and guiding center operators of a particle coupled to a homogenous magnetic filed is constructed. The Pauli Hamiltonian rewrites in this way as a power series in the magnetic length $l_B= \sqrt{\hbar c/eB}$ making the problem amenable to a perturbative analysis. The first two terms of the series are explicitly constructed. The effective adiabatic dynamics turns to be in coupling with a gauge filed and a scalar potential. The mechanism producing such magnetic-induced geometric-magnetism is investigated in some detail.

hep-th↗
arXiv1995

Adiabatic Motion of a Quantum Particle in a Two-Dimensional Magnetic Field

The adiabatic motion of a charged, spinning, quantum particle in a two - dimensional magnetic field is studied. A suitable set of operators generalizing the cinematical momenta and the guiding center operators of a particle moving in a homogeneous magnetic field is constructed. This allows us to separate the two degrees of freedom of the system into a {\sl fast} and a {\sl slow} one, in the classical limit, the rapid rotation of the particle around the guiding center and the slow guiding center drift. In terms of these operators the Hamiltonian of the system rewrites as a power series in the magnetic length $\lb=\sqrt{\hbar c\over eB}$ and the fast and slow dynamics separates. The effective guiding center Hamiltonian is obtained to the second order in the adiabatic parameter $\lb$ and reproduces correctly the classical limit.

hep-th↗