49,196 research outputs found
Light composite Higgs boson from the normalized Bethe-Salpeter equation
Scalar composite boson masses have been computed in QCD and Technicolor
theories with the help of the homogeneous Bethe-Salpeter equation (BSE),
resulting in a scalar mass that is twice the dynamically generated fermion or
technifermion mass (). We show that in the case of walking (or
quasi-conformal) technicolor theories, where the behavior with the
momenta may be quite different from the one predicted by the standard operator
product expansion, this result is incomplete and we must consider the effect of
the normalization condition of the BSE to determine the scalar masses. We
compute the composite Higgs boson mass for several groups with technifermions
in the fundamental and higher dimensional representations and comment about the
experimental constraints on these theories, which indicate that models based on
walking theories with fermions in the fundamental representation may, within
the limitations of our approach, have masses quite near the actual direct
exclusion limit.Comment: 9 pages, 4 figures, minor corrections, to appear in Physical Review
An approach for the detection of point-sources in very high resolution microwave maps
This paper deals with the detection problem of extragalactic point-sources in
multi-frequency, microwave sky maps that will be obtainable in future cosmic
microwave background radiation (CMB) experiments with instruments capable of
very high spatial resolution. With spatial resolutions that can be of order of
0.1-1.0 arcsec or better, the extragalactic point-sources will appear isolated.
The same holds also for the compact structures due to the Sunyaev-Zeldovich
(SZ) effect (both thermal and kinetic). This situation is different from the
maps obtainable with instruments as WMAP or PLANCK where, because of the
smaller spatial resolution (approximately 5-30 arcmin), the point-sources and
the compact structures due to the SZ effect form a uniform noisy background
(the "confusion noise"). Hence, the point-source detection techniques developed
in the past are based on the assumption that all the emissions that contribute
to the microwave background can be modeled with homogeneous and isotropic
(often Gaussian) random fields and make use of the corresponding spatial
power-spectra. In the case of very high resolution observations such an
assumption cannot be adopted since it still holds only for the CMB. Here, we
propose an approach based on the assumption that the diffuse emissions that
contribute to the microwave background can be locally approximated by
two-dimensional low order polynomials. In particular, two sets of numerical
techniques are presented containing two different algorithms each. The
performance of the algorithms is tested with numerical experiments that mimic
the physical scenario expected for high Galactic latitude observations with the
Atacama Large Millimeter/Submillimeter Array (ALMA).Comment: Accepted for publication on "Astronomy & Astrophysics". arXiv admin
note: substantial text overlap with arXiv:1206.4536 Replaced version is the
accepted one and published in A&
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