46,811 research outputs found
Asymptotic SER and Outage Probability of MIMO MRC in Correlated Fading
This letter derives the asymptotic symbol error rate (SER) and outage
probability of multiple-input multiple-output (MIMO) maximum ratio combining
(MRC) systems. We consider Rayleigh fading channels with both transmit and
receive spatial correlation. Our results are based on new asymptotic
expressions which we derive for the p.d.f. and c.d.f. of the maximum eigenvalue
of positive-definite quadratic forms in complex Gaussian matrices. We prove
that spatial correlation does not affect the diversity order, but that it
reduces the array gain and hence increases the SER in the high SNR regime.Comment: 10 pages, 2 figures, to appear in IEEE Signal Processing Letter
Current experimental constraints on NMSSM with large lambda
The next-to-minimal supersymmetric model (NMSSM) with a large lambda (the
mixing parameter between the singlet and doublet Higgs fields) is well
motivated since it can significantly push up the upper bound on the SM-like
Higgs boson mass to solve the little hierarchy problem. In this work we examine
the current experimental constraints on the NMSSM with a large lambda, which
include the direct search for Higgs boson and sparticles at colliders, the
indirect constraints from precision electroweak measurements, the cosmic dark
matter relic density, the muon anomalous magnetic moment, as well as the
stability of the Higgs potential. We find that, with the increase of lambda,
parameters like tan-beta, M_A, mu and M_2 are becoming more stringently
constrained. It turns out that the maximal reach of lambda is limited by the
muon anomalous magnetic moment, and for smuon masses of 200 GeV (500 GeV) the
parameter space with lambda > 1.5 (0.6) is excluded.Comment: Version in PRD (figs and discussions added
Thermodynamics of lattice QCD with 2 flavours of colour-sextet quarks: A model of walking/conformal Technicolor
QCD with two flavours of massless colour-sextet quarks is considered as a
model for conformal/walking Technicolor. If this theory possess an infrared
fixed point, as indicated by 2-loop perturbation theory, it is a
conformal(unparticle) field theory. If, on the other hand, a chiral condensate
forms on the weak-coupling side of this would-be fixed point, the theory
remains confining. The only difference between such a theory and regular QCD is
that there is a range of momentum scales over which the coupling constant runs
very slowly (walks). In this first analysis, we simulate the lattice version of
QCD with two flavours of staggered quarks at finite temperatures on lattices of
temporal extent and 6. The deconfinement and chiral-symmetry
restoration couplings give us a measure of the scales associated with
confinement and chiral-symmetry breaking. We find that, in contrast to what is
seen with fundamental quarks, these transition couplings are very different.
for each of these transitions increases significantly from
and as expected for the finite temperature transitions of an
asymptotically-free theory. This suggests a walking rather than a conformal
behaviour, in contrast to what is observed with Wilson quarks. In contrast to
what is found for fundamental quarks, the deconfined phase exhibits states in
which the Polyakov loop is oriented in the directions of all three cube roots
of unity. At very weak coupling the states with complex Polyakov loops undergo
a transition to a state with a real, negative Polyakov loop.Comment: 21 pages, 9 figures, Revtex with postscript figures. One extra
reference was added; text is unchanged. Corrected typographical erro
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