arXiv subjects

Robert W. Johnson

Publications and source records attributed to Robert W. Johnson.

40 records · Page 3Linked to original sources

arXiv2006

Quantum Mechanics associated with a Finite Group

I describe, in the simplified context of finite groups and their representations, a mathematical model for a physical system that contains both its quantum and classical aspects. The physically observable system is associated with the space containing elements fxf for f an element in the regular representation of a given finite group G. The Hermitian portion of fxf is the Wigner distribution of f whose convolution with a test function leads to a mathematical description of the quantum measurement process. Starting with the Jacobi group that is formed from the semidirect product of the Heisenberg group with its automorphism group SL(2,F{N}) for N an odd prime number I show that the classical phase space is the first order term in a series of subspaces of the Hermitian portion of fxf that are stable under SL(2,F{N}). I define a derivative that is analogous to a pseudodifferential operator to enable a treatment that parallels the continuum case. I give a new derivation of the Schrodinger-Weil representation of the Jacobi group. Keywords: quantum mechanics, finite group, metaplectic. PACS: 03.65.Fd; 02.10.De; 03.65.Ta.

quant-ph↗

arXiv2002

Spin Resolution of Glueballs in 2+1 Dimensional Lattice Gauge Theory

Conventional lattice gauge theory assigns the lowest spin compatible with the symmetry channel of a given operator to the state coupling to that operator. Operators on a cubic lattice, however, are only defined on angles of pi/2, hence states with spin equal modulo 4 may overlap significantly. This paper explores a new technique for generating lattice operators that may be placed onto the lattice at angles other than pi/2, thereby resolving this modulo 4 ambiguity. Calculations of the mass of states with spin equal t o 0, 2, and 4 are performed in the positive parity and charge conjugation channe l and compared to the spectrum from previous lattice calculations. These masses compare well for spin 0 and 2, and for spin 4 the mass agrees with a state conv entionally assigned spin 0, raising the possibility of mis-identification of the spin of states coupling to some traditional operators.

hep-lat↗

arXiv2002

String models of glueballs and the spectrum of SU(N) gauge theories in 2+1 dimensions

The spectrum of glueballs in 2+1 dimensions is calculated within an extended class of Isgur-Paton flux tube models and is compared to lattice calculations of the low-lying SU(N) glueball mass spectra. Our modifications of the model include a string curvature term and different ways of dealing with the flux tube width. We find that the generic model is remarkably successful at reproducing the positive charge conjugation, C=+, sector of the spectrum. The only large (and robust) discrepancy involves the 0-+ state. This raises the interesting possibility that the lattice spin identification is mistaken and that this state is in fact 4-+. In addition, the Isgur-Paton model does not incorporate any mechanism for splitting C=+ from C=- (in contrast to the case in 3+1 dimensions), while the `observed' spectrum shows a substantial splitting. We explore several modifications of the model in an attempt to incorporate this physics in a natural way. At the qualitative level we find that this constrains our choice to a picture in which the C=+/- splitting is driven by mixing with new states built on closed loops of adjoint flux. However a detailed numerical comparison suggests that a model incorporating an additional direct mixing between loops of opposite orientation is likely to work better; and that, in any case, a non-zero curvature term will be required. We also point out that a characteristic of any string model of glueballs is that the SU(N=infinity) mass spectrum will consist of multiple towers of states that are scaled up copies of each other. To test this will require a lattice mass spectrum that extends to somewhat larger masses than currently available.

hep-ph↗

arXiv2000

Fiber with Intrinsic Action on a 1+1 Dimensional Spacetime

I construct an algebraic model for a typical fiber on a 1+1 dimensional spacetime. The vector space comprising the fiber is composed of elements formed from the direct product of two copies of an element x in the D2=C2xC2 finite group algebra over the real numbers. The fiber contains subspaces whose elements are associated with the tangent and momentum vectors of trajectories in the manifold. The fiber also contains a subspace whose elements are associated with the local flow of action of each trajectory. The condition of minimum action translates into a constraint on the original vector x in the direct product structure.

math.DG↗