5,554 research outputs found
Resonance saturation in the odd-intrinsic parity sector of low-energy QCD
Using the large N_C approximation we have constructed the most general chiral
resonance Lagrangian in the odd-intrinsic parity sector that can generate low
energy chiral constants up to O(p^6). Integrating out the resonance fields
these O(p^6) constants are expressed in terms of resonance couplings and
masses. The role of eta' is discussed and its contribution is explicitly
factorized. Using the resonance basis we have also calculated two QCD Green
functions of currents: and and found, imposing high energy
constraints, additional relations for resonance couplings. We have studied
several phenomenological implications based on these correlators from which let
us mention here our prediction for the pi0-pole contribution to the muon g-2
factor: .Comment: 42 pages, 3 figure
Commuting symmetry operators of the Dirac equation, Killing-Yano and Schouten-Nijenhuis brackets
In this paper we derive the most general first-order symmetry operator
commuting with the Dirac operator in all dimensions and signatures. Such an
operator splits into Clifford even and Clifford odd parts which are given in
terms of odd Killing-Yano and even closed conformal Killing-Yano inhomogeneous
forms respectively. We study commutators of these symmetry operators and give
necessary and sufficient conditions under which they remain of the first-order.
In this specific setting we can introduce a Killing-Yano bracket, a bilinear
operation acting on odd Killing-Yano and even closed conformal Killing-Yano
forms, and demonstrate that it is closely related to the Schouten-Nijenhuis
bracket. An important non-trivial example of vanishing Killing-Yano brackets is
given by Dirac symmetry operators generated from the principal conformal
Killing-Yano tensor [hep-th/0612029]. We show that among these operators one
can find a complete subset of mutually commuting operators. These operators
underlie separability of the Dirac equation in Kerr-NUT-(A)dS spacetimes in all
dimensions [arXiv:0711.0078].Comment: 37 pages, no figure
Variability of fundamental constants
If the fine structure constant is not really constant, is this due to a
variation of , , or ? It is argued that the only reasonable
conclusion is a variable speed of light.Comment: preliminary draft, comments welcom
Dualities between Poisson brackets and antibrackets
Recently it has been shown that antibrackets may be expressed in terms of
Poisson brackets and vice versa for commuting functions in the original
bracket. Here we also introduce generalized brackets involving higher
antibrackets or higher Poisson brackets where the latter are of a new type. We
give generating functions for these brackets for functions in arbitrary
involutions in the original bracket. We also give master equations for
generalized Maurer-Cartan equations. The presentation is completely symmetric
with respect to Poisson brackets and antibrackets.Comment: 24 pages,Latexfile,corrected (2.7-8) and removed text between (2.9)
and (2.10
Nondestructive readout for a superconducting flux qubit
We present a new readout method for a superconducting flux qubit, based on
the measurement of the Josephson inductance of a superconducting quantum
interference device that is inductively coupled to the qubit. The intrinsic
flux detection efficiency and back-action are suitable for a fast and
nondestructive determination of the quantum state of the qubit, as needed for
readout of multiple qubits in a quantum computer. We performed spectroscopy of
a flux qubit and we measured relaxation times of the order of 80 .Comment: 4 pages, 4 figures; modified content, figures and references;
accepted for publication in Phys. Rev. Let
Low-crosstalk bifurcation detectors for coupled flux qubits
We present experimental results on the crosstalk between two AC-operated
dispersive bifurcation detectors, implemented in a circuit for high-fidelity
readout of two strongly coupled flux qubits. Both phase-dependent and
phase-independent contributions to the crosstalk are analyzed. For proper
tuning of the phase the measured crosstalk is 0.1 % and the correlation between
the measurement outcomes is less than 0.05 %. These results show that
bifurcative readout provides a reliable and generic approach for multi-partite
correlation experiments.Comment: Copyright 2010 American Institute of Physics. This article may be
downloaded for personal use only. Any other use requires prior permission of
the author and the American Institute of Physics. The following article
appeared in Applied Physics Letters and may be found at
http://link.aip.org/link/?apl/96/12350
Do Killing-Yano tensors form a Lie Algebra?
Killing-Yano tensors are natural generalizations of Killing vectors. We
investigate whether Killing-Yano tensors form a graded Lie algebra with respect
to the Schouten-Nijenhuis bracket. We find that this proposition does not hold
in general, but that it does hold for constant curvature spacetimes. We also
show that Minkowski and (anti)-deSitter spacetimes have the maximal number of
Killing-Yano tensors of each rank and that the algebras of these tensors under
the SN bracket are relatively simple extensions of the Poincare and (A)dS
symmetry algebras.Comment: 17 page
Inner topological structure of Hopf invariant
In light of -mapping topological current theory, the inner topological
structure of Hopf invariant is investigated. It is revealed that Hopf invariant
is just the winding number of Gauss mapping. According to the inner structure
of topological current, a precise expression for Hopf invariant is also
presented. It is the total sum of all the self-linking and all the linking
numbers of the knot family.Comment: 13pages, no figure. Accepted by J.Math.Phy
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