1,366 research outputs found
Non-Pauli Effects from Noncommutative Spacetimes
Noncommutative spacetimes lead to nonlocal quantum field theories (qft's)
where spin-statistics theorems cannot be proved. For this reason, and also
backed by detailed arguments, it has been suggested that they get corrected on
such spacetimes leading to small violations of the Pauli principle. In a recent
paper \cite{Pauli}, Pauli-forbidden transitions from spacetime noncommutativity
were calculated and confronted with experiments. Here we give details of the
computation missing from this paper. The latter was based on a spacetime
different from the Moyal plane. We argue that it
quantizes time in units of . Energy is then conserved only mod
. Issues related to superselection rules raised by non-Pauli
effects are also discussed in a preliminary manner.Comment: 15 Pages, 1 Table, Full details and further developments of
arXiv:1003.2250. This version is close to the one accepted by JHE
Scalar Field Theory on Fuzzy S^4
Scalar fields are studied on fuzzy and a solution is found for the
elimination of the unwanted degrees of freedom that occur in the model. The
resulting theory can be interpreted as a Kaluza-Klein reduction of CP^3 to S^4
in the fuzzy context.Comment: 16 pages, LaTe
Continuous Time-Dependent Measurements: Quantum Anti-Zeno Paradox with Applications
We derive differential equations for the modified Feynman propagator and for
the density operator describing time-dependent measurements or histories
continuous in time. We obtain an exact series solution and discuss its
applications. Suppose the system is initially in a state with density operator
and the projection operator is measured
continuously from to , where is a projector obeying and a unitary operator obeying and some smoothness
conditions in . Then the probability of always finding from to is unity. Generically and the watched system is sure to
change its state, which is the anti-Zeno paradox noted by us recently. Our
results valid for projectors of arbitrary rank generalize those obtained by
Anandan and Aharonov for projectors of unit rank.Comment: 16 pages, latex; new material and references adde
Chemical composition of essential oil from the leaves of Premna coriacea Clarke
In this study, the chemical composition of the essential oil of Premna coriacea leaves was investigated. Extraction by hydrodistillation followed by gas chromatography and mass spectrometry (GC-MS) yielded 27 compounds representing 99.89% of the oil. The major volatile components of the oil were aromadendrene (23.51), caryophyllene (19.27), tetracontane (11.90), 17-pentatriacontene (6.61), 3',8,8'-trimethoxy-3-piperidyl-2,2'- binaphthalene-1,1',4,4'-tetrone (4.68), cis-α-bisabolene (4.65), octadecane, 3-ethyl-5-(2-ethylbutyl)- (4.21), 2-mercaptobenzothiazole (3.17) and tetratetracontane (2.38).Keywords: Premna coriacea, essential oil, aromadendrene, caryophylleneAfrican Journal of Biotechnology Vol. 12(20), pp. 2914-291
Phase Space Reduction and Vortex Statistics: An Anyon Quantization Ambiguity
We examine the quantization of the motion of two charged vortices in a
Ginzburg--Landau theory for the fractional quantum Hall effect recently
proposed by the first two authors. The system has two second-class constraints
which can be implemented either in the reduced phase space or
Dirac-Gupta-Bleuler formalism. Using the intrinsic formulation of statistics,
we show that these two ways of implementing the constraints are inequivalent
unless the vortices are quantized with conventional statistics; either
fermionic or bosonic.Comment: 14 pages, PHYZZ
Causality and statistics on the Groenewold-Moyal plane
Quantum theories constructed on the noncommutative spacetime called the
Groenewold-Moyal plane exhibit many interesting properties such as Lorentz and
CPT noninvariance, causality violation and twisted statistics. We show that
such violations lead to many striking features that may be tested
experimentally. These theories predict Pauli forbidden transitions due to
twisted statistics, anisotropies in the cosmic microwave background radiation
due to correlations of observables in spacelike regions and Lorentz and CPT
violations in scattering amplitudes.Comment: 12 pages, 1 figure. Based on the talk given by APB at the Workshop
"Theoretical and Experimental Aspects of the Spin Statisics Connection and
Related Symmetries", Stazione Marittima Conference Center, Trieste, Italy
from the 21st to the 25th of October 200
A hierarchical adaptive nonlinear model predictive control approach for maximizing tire force usage in autonomous vehicles
The ability to reliably maximize tire force usage would improve the safety of
autonomous vehicles, especially in challenging edge cases. However, vehicle
control near the limits of handling has many challenges, including robustly
contending with tire force saturation, balancing model fidelity and
computational efficiency, and coordinating inputs with the lower level chassis
control system. This work studies Nonlinear Model Predictive Control for limit
handling, specifically adapting to changing tire-road conditions and maximally
allocating tire force utilization. We present a novel hierarchical framework
that combines a single-track model with longitudinal weight transfer dynamics
in the predictive control layer, with lateral brake distribution occurring at
the chassis control layer. This vehicle model is simultaneously used in an
Unscented Kalman Filter for online friction estimation. Comparative experiments
on a full-scale vehicle operating on a race track at up to 95% of maximum tire
force usage demonstrate the overall practical effectiveness of this approach.Comment: Preprint of accepted paper in Field Robotic
Dynamical generation of a nontrivial index on the fuzzy 2-sphere
In the previous paper hep-th/0312199 we studied the 't Hooft-Polyakov (TP)
monopole configuration in the U(2) gauge theory on the fuzzy 2-sphere and
showed that it has a nonzero topological charge in the formalism based on the
Ginsparg-Wilson relation. In this paper, by showing that the TP monopole
configuration is stabler than the U(2) gauge theory without any condensation in
the Yang-Mills-Chern-Simons matrix model, we will present a mechanism for
dynamical generation of a nontrivial index. We further analyze the instability
and decay processes of the U(2) gauge theory and the TP monopole configuration.Comment: Latex2e, 30 pages, 4 figures, the topological charge for a monopole
configuration is corrected, reference added, the final version to appear in
Physical Review D (the typos mentioned in the erratum are corrected
Unusual Thermodynamics on the Fuzzy 2-Sphere
Higher spin Dirac operators on both the continuum sphere() and its fuzzy
analog() come paired with anticommuting chirality operators. A
consequence of this is seen in the fermion-like spectrum of these operators
which is especially true even for the case of integer-spin Dirac operators.
Motivated by this feature of the spectrum of a spin 1 Dirac operator on
, we assume the spin 1 particles obey Fermi-Dirac statistics. This
choice is inspite of the lack of a well defined spin-statistics relation on a
compact surface such as . The specific heats are computed in the cases of
the spin and spin 1 Dirac operators. Remarkably the specific heat
for a system of spin particles is more than that of the spin 1
case, though the number of degrees of freedom is more in the case of spin 1
particles. The reason for this is inferred through a study of the spectrums of
the Dirac operators in both the cases. The zero modes of the spin 1 Dirac
operator is studied as a function of the cut-off angular momentum and is
found to follow a simple power law. This number is such that the number of
states with positive energy for the spin 1 and spin system become
comparable. Remarks are made about the spectrums of higher spin Dirac operators
as well through a study of their zero-modes and the variation of their spectrum
with degeneracy. The mean energy as a function of temperature is studied in
both the spin and spin 1 cases. They are found to deviate from
the standard ideal gas law in 2+1 dimensions.Comment: 19 pages, 7 figures. The paper has been significantly modified. Main
results are unchange
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