104 research outputs found
Handbook for Surveillance and Monitoring of European Habitats. First Edition
The primary objective of this Handbook is to describe the methodology appropriate for coordinating information on habitats in order to obtain statistically robust estimates of their extent and associated changes in biodiversity. Such detailed rules are necessary if surveillance; i.e., recording information at a point in time; is to be repeated subsequently as monitoring, otherwise real changes cannot be separated reliably from background noise. The BioHab procedure will also map all Pan-European classifications, such as EUNIS, where possible, as a basis for their surveillance and monitoring throughout Europe. The basis of the General Habitat Categories is the classification of plant Life Forms produced by the Danish botanist Raunkiaer early in the 20th century. These Life Forms e.g. annuals or trees, transcend species. They are based on the scientific hypothesis that habitat structure is related to the environment. The BioHab General Habitat Categories cover the pan-European region (except Turkey) with 130 GHC¿s derived from 16 Life Forms (LF¿s). They have been field tested in all the environmental zones in Europe. Variation within a General Habitat Category is then expressed by environmental and global qualifiers, which are combinations of soil humidity, nutrient status, acidity and other habitat characteristics. Important additional information is given by adding codes from predefined lists of site and management qualifiers
SU(3) Predictions for Weak Decays of Doubly Heavy Baryons -- including SU(3) breaking terms
We find expressions for the weak decay amplitudes of baryons containing two b
quarks (or one b and one c quark -- many relationship are the same) in terms of
unknown reduced matrix elements. This project was originally motivated by the
request of the FNAL Run II b Physics Workshop organizers for a guide to
experimentalists in their search for as yet unobserved hadrons. We include an
analysis of linear SU(3) breaking terms in addition to relationships generated
by unbroken SU(3) symmetry, and relate these to expressions in terms of the
complete set of possible reduced matrix elements.Comment: 49 page
Studying Kaon-pion S-wave scattering in K-matrix formalism
We generalize our previous work on \pi\pi scattering to K\pi scattering, and
re-analyze the experiment data of K\pi scattering below 1.6 GeV. Without any
free parameter, we explain K\pi I=3/2 S-wave phase shift very well by using
t-channel rho and u-channel K^* meson exchange. With the t-channel and
u-channel meson exchange fixed as the background term, we fit the K\pi I=1/2
S-wave data of the LASS experiment quite well by introducing one or two
s-channel resonances. It is found that there is only one s-channel resonance
between K\pi threshold and 1.6 GeV, i.e., K_0^*(1430) with a mass around
1438~1486 MeV and a width about 346 MeV, while the t-channel rho exchange gives
a pole at (450-480i) MeV for the amplitude.Comment: REVTeX4 file, 11 pages and 3 figure
Strange form factors in the context of SAMPLE, HAPPEX, and A4 experiments
The strange properties of the nucleon are investigated within the framework
of the SU(3) chiral quark-soliton model assuming isospin symmetry and applying
the symmetry conserving SU(3) quantization. We present the form factors
, and the electric and magnetic strange form
factors incorporating pion and kaon asymptotics. The results
show a fairly good agreement with the recent experimental data from the SAMPLE
and HAPPEX collaborations. We also present predictions for future measurements
including the A4 experiment at MAMI (Mainz).Comment: 10 pages with four figures. RevTeX4 is used. Few lines are changed.
Accepted for publication in Phys.Rev.
Loop effects and non-decoupling property of SUSY QCD in
One-loop SUSY QCD radiative correction to cross section is
calculated in the Minimal Supersymmetric Standard Model. We found that SUSY QCD
is non-decoupling if the gluino mass and the parameter , or
are at the same order and get large. The non-decoupling contribution can be
enhanced by large and therefore large corrections to the hadronic
production rates at the Tevatron and LHC are expected in the large
limit. The fundamental reason for such non-decoupling behavior is found to be
some couplings in the loops being proportional to SUSY mass parameters.Comment: 15 pages, 5 PS figures. A proof of non-decouplings of SUSY-QCD,
Comments on corresponding QCD correction and references adde
Reevaluation of the role of nuclear uncertainties in experiments on atomic parity violation with isotopic chains
In light of new data on neutron distributions from experiments with
antiprotonic atoms [ Trzcinska {\it et al.}, Phys. Rev. Lett. 87, 082501
(2001)], we reexamine the role of nuclear-structure uncertainties in the
interpretation of measurements of parity violation in atoms using chains of
isotopes of the same element. With these new nuclear data, we find an
improvement in the sensitivity of isotopic chain measurements to ``new
physics'' beyond the standard model. We compare possible constraints on ``new
physics'' with the most accurate to date single-isotope probe of parity
violation in the Cs atom. We conclude that presently isotopic chain experiments
employing atoms with nuclear charges Z < 50 may result in more accurate tests
of the weak interaction.Comment: 6 pages, 1 fig., submitted to Phys. Rev.
Detection of Supernova Neutrinos by Neutrino-Proton Elastic Scattering
We propose that neutrino-proton elastic scattering, ,
can be used for the detection of supernova neutrinos in scintillator detectors.
Though the proton recoil kinetic energy spectrum is soft, with , and the scintillation light output from slow, heavily ionizing
protons is quenched, the yield above a realistic threshold is nearly as large
as that from . In addition, the measured proton
spectrum is related to the incident neutrino spectrum, which solves a
long-standing problem of how to separately measure the total energy and
temperature of , , , and .
The ability to detect this signal would give detectors like KamLAND and
Borexino a crucial and unique role in the quest to detect supernova neutrinos.Comment: 10 pages, 9 figures, revtex
Rare charm meson decays D->Pl^+l^- and c->ul^+l^- in SM and MSSM
We study the nine possible rare charm meson decays D->Pl^+l^-
(P=pi,K,eta,eta') using the Heavy Meson Chiral Lagrangians and find them to be
dominated by the long distance contributions. The decay D^+ -> pi^+l^+l^- with
the branching ratio 1*10^(-6) is expected to have the best chances for an early
experimental discovery. The short distance contribution in the five Cabibbo
suppressed channels arises via the c->ul^+l^- transition; we find that this
contribution is detectable only in the D->pi l^+l^- decay, where it dominates
the differential spectrum at high-q^2. The general Minimal Supersymmetric
Standard Model can enhance the c->ul^+l^- rate by up to an order of magnitude;
its effect on the D->Pl^+l^- rates is small since the c->ul^+l^- enhancement is
sizable in low-q^2 region, which is inhibited in the hadronic decay.Comment: 17 page
Extra Families, Higgs Spectrum and Oblique Corrections
The standard model accommodates, but does not explain, three families of
leptons and quarks, while various extensions suggest extra matter families. The
oblique corrections from extra chiral families with relatively light
(weak-scale) masses, , are analyzed and used to constrain the
number of extra families and their spectrum. The analysis is motivated, in
part, by recent N = 2 supersymmetry constructions, but is performed in a
model-independent way. It is shown that the correlations among the
contributions to the three oblique parameters, rather than the contribution to
a particular one, provide the most significant bound. Nevertheless, a single
extra chiral family with a constrained spectrum is found to be consistent with
precision data without requiring any other new physics source. Models with
three additional families may also be accommodated but only by invoking
additional new physics, most notably, a two-Higgs-doublet extension. The
interplay between the spectra of the extra fermions and the Higgs boson(s) is
analyzed in the case of either one or two Higgs doublets, and its implications
are explored. In particular, the precision bound on the SM-like Higgs boson
mass is shown to be significantly relaxed in the presence of an extra
relatively light chiral family.Comment: 20 pages, 8 figures, version for PR
Do solar neutrinos decay?
Despite the fact that the solar neutrino flux is now well-understood in the
context of matter-affected neutrino mixing, we find that it is not yet possible
to set a strong and model-independent bound on solar neutrino decays. If
neutrinos decay into truly invisible particles, the Earth-Sun baseline defines
a lifetime limit of \tau/m \agt 10^{-4} s/eV. However, there are many
possibilities which must be excluded before such a bound can be established.
There is an obvious degeneracy between the neutrino lifetime and the mixing
parameters. More generally, one must also allow the possibility of active
daughter neutrinos and/or antineutrinos, which may partially conceal the
characteristic features of decay. Many of the most exotic possibilities that
presently complicate the extraction of a decay bound will be removed if the
KamLAND reactor antineutrino experiment confirms the large-mixing angle
solution to the solar neutrino problem and measures the mixing parameters
precisely. Better experimental and theoretical constraints on the B
neutrino flux will also play a key role, as will tighter bounds on absolute
neutrino masses. Though the lifetime limit set by the solar flux is weak, it is
still the strongest direct limit on non-radiative neutrino decay. Even so,
there is no guarantee (by about eight orders of magnitude) that neutrinos from
astrophysical sources such as a Galactic supernova or distant Active Galactic
Nuclei will not decay.Comment: Very minor corrections, corresponds to published versio
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