5,932 research outputs found
Comment on "Classical interventions in quantum systems II. Relativistic invariance"
In a recent paper [Phys. Rev. A 61, 022117 (2000)], quant-ph/9906034, A.
Peres argued that quantum mechanics is consistent with special relativity by
proposing that the operators that describe time evolution do not need to
transform covariantly, although the measurable quantities need to transform
covariantly. We discuss the weaknesses of this proposal.Comment: 4 pages, to appear in Phys. Rev.
Infinite matrices may violate the associative law
The momentum operator for a particle in a box is represented by an infinite
order Hermitian matrix . Its square is well defined (and diagonal),
but its cube is ill defined, because . Truncating these
matrices to a finite order restores the associative law, but leads to other
curious results.Comment: final version in J. Phys. A28 (1995) 1765-177
Revising Limits on Neutrino-Majoron Couplings
Any theory that have a global spontaneously broken symmetry will imply the
existence of very light neutral bosons or massless bosons (sometimes called
Majorons). For most of these models we have neutrino-Majoron couplings, that
appear as additional branching ratios in decays of mesons and leptons. Here we
present an updated limits on the couplings between the electron, muon and tau
neutrinos and Majorons. For such we analyze the possible effects of Majoron
emission in both meson and lepton decays. In the latter we also include an
analysis of the muon decay spectrum. Our results are
, and
at 90 % C. L., where .Comment: 12 pages, 5 figure
Spacings and pair correlations for finite Bernoulli convolutions
We consider finite Bernoulli convolutions with a parameter
supported on a discrete point set, generically of size . These sequences
are uniformly distributed with respect to the infinite Bernoulli convolution
measure , as tends to infinity. Numerical evidence suggests that for
a generic , the distribution of spacings between appropriately rescaled
points is Poissonian. We obtain some partial results in this direction; for
instance, we show that, on average, the pair correlations do not exhibit
attraction or repulsion in the limit. On the other hand, for certain algebraic
the behavior is totally different.Comment: 17 pages, 6 figure
Quantum mechanics explained
The physical motivation for the mathematical formalism of quantum mechanics
is made clear and compelling by starting from an obvious fact - essentially,
the stability of matter - and inquiring into its preconditions: what does it
take to make this fact possible?Comment: 29 pages, 5 figures. v2: revised in response to referee comment
Bell's inequality with Dirac particles
We study Bell's inequality using the Bell states constructed from four
component Dirac spinors. Spin operator is related to the Pauli-Lubanski pseudo
vector which is relativistic invariant operator. By using Lorentz
transformation, in both Bell states and spin operator, we obtain an observer
independent Bell's inequality, so that it is maximally violated as long as it
is violated maximally in the rest frame.Comment: 7 pages. arXiv admin note: text overlap with arXiv:quant-ph/0308156
by other author
Charge and Spin Transport in the One-dimensional Hubbard Model
In this paper we study the charge and spin currents transported by the
elementary excitations of the one-dimensional Hubbard model. The corresponding
current spectra are obtained by both analytic methods and numerical solution of
the Bethe-ansatz equations. For the case of half-filling, we find that the
spin-triplet excitations carry spin but no charge, while charge -spin
triplet excitations carry charge but no spin, and both spin-singlet and charge
-spin-singlet excitations carry neither spin nor charge currents.Comment: 24 pages, 14 figure
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