4,800 research outputs found
Will at least one of the Higgs bosons of the next-to-minimal supersymmetric extension of the Standard Model be observable at LEP2 or the LHC?
We demonstrate that there are regions of parameter space in the
next-to-minimal (i.e. two-Higgs-doublet, one-Higgs-singlet superfield)
supersymmetric extension of the SM for which none of the Higgs bosons are
observable either at LEP2 with and an integrated luminosity
of or at the LHC with .Comment: 6 pages, full postscript file also available via anonymous ftp at
ftp://ucdhep.ucdavis.edu/gunion/nmssm_sm96.ps To appear in ``Proceedings of
the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics'
Quantum coherence in the presence of unobservable quantities
State representations summarize our knowledge about a system. When
unobservable quantities are introduced the state representation is typically no
longer unique. However, this non-uniqueness does not affect subsequent
inferences based on any observable data. We demonstrate that the inference-free
subspace may be extracted whenever the quantity's unobservability is guaranteed
by a global conservation law. This result can generalize even without such a
guarantee. In particular, we examine the coherent-state representation of a
laser where the absolute phase of the electromagnetic field is believed to be
unobservable. We show that experimental coherent states may be separated from
the inference-free subspaces induced by this unobservable phase. These physical
states may then be approximated by coherent states in a relative-phase Hilbert
space
Partial Observability and its Consistency for PDEs
In this paper, a quantitative measure of partial observability is defined for
PDEs. The quantity is proved to be consistent if the PDE is approximated using
well-posed approximation schemes. A first order approximation of an
unobservability index using an empirical Gramian is introduced. Several
examples are presented to illustrate the concept of partial observability,
including Burgers' equation and a one-dimensional nonlinear shallow water
equation.Comment: 5 figures, 25 pages. arXiv admin note: substantial text overlap with
arXiv:1111.584
Non Abelian gauge symmetries induced by the unobservability of extra-dimensions in a Kaluza-Klein approach
In this work we deal with the extension of the Kaluza-Klein approach to a
non-Abelian gauge theory; we show how we need to consider the link between the
n-dimensional model and a four-dimensional observer physics, in order to
reproduce fields equations and gauge transformations in the four-dimensional
picture. More precisely, in fields equations any dependence on
extra-coordinates is canceled out by an integration, as consequence of the
unobservability of extra-dimensions. Thus, by virtue of this extra-dimensions
unobservability, we are able to recast the multidimensional Einstein equations
into the four-dimensional Einstein-Yang-Mills ones, as well as all the right
gauge transformations of fields are induced. The same analysis is performed for
the Dirac equation describing the dynamics of the matter fields and, again, the
gauge coupling with Yang-Mills fields are inferred from the multidimensional
free fields theory, together with the proper spinors transformations.Comment: 5 pages, no figures, to appear in Mod. Phys. Lett.
The Consistency of Partial Observability for PDEs
In this paper, a new definition of observability is introduced for PDEs. It
is a quantitative measure of partial observability. The quantity is proved to
be consistent if approximated using well posed approximation schemes. A first
order approximation of an unobservability index using empirical gramian is
introduced. For linear systems with full state observability, the empirical
gramian is equivalent to the observability gramian in control theory. The
consistency of the defined observability is exemplified using a Burgers'
equation.Comment: 28 pages, 3 figure
Chern-kernels and anomaly cancellation in M-theory
This paper deals with magnetic equations of the type dH=J where the current J
is a delta-function on a brane worldvolume and H a p-form field strength. In
many situations in M-theory this equation needs to be solved for H in terms of
a potential. A standard universality class of solutions, involving
Dirac-branes, gives rise to strong intermediate singularities in H which in
many physically relevant cases lead to inconsistencies. In this paper we
present an alternative universality class of solutions for magnetic equations
in terms of Chern-kernels, and provide relevant applications, among which the
anomaly-free effective action for open M2-branes ending on M5-branes. The
unobservability of the Dirac-brane requires a Dirac quantization condition; we
show that the requirement of ``unobservability'' of the Chern-kernel leads in
M-theory to classical gravitational anomalies which cancel precisely their
quantum counterparts.Comment: LaTex, 39 pages, references and comments adde
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