4,684 research outputs found
Graphical statistics to explore the natural and anthropogenic processes influencing the inorganic quality of drinking water, ground water and surface water
Plots of cumulative distribution functions (CDF) are a simple but powerful exploratory data analysis (EDA) tool to evaluate and compare statistical data distributions. Here, empirical CDF plots are used to compare results of four large (476 to 884 samples) national- to continental-scale inorganic water chemistry data sets: (1) European surface water, (2) European tap water, (3) European bottled waters as a proxy for groundwater and (4) Norwegian crystalline bedrock rock groundwater, all analysed at the same laboratory, albeit at different times. For many parameters (e.g., Ba, Cl-, K, SO4
2-) median values and ranges are, given the differing origins and, in some cases, treatment processes of the waters, surprisingly comparable. Unusually high concentrations of some other elements (e.g., B, Be, Br, Cs, F-, Ge, Li, Rb, Te and Zr) appear to be characteristic of deeper-seated, mature groundwaters. Other influences that can be inferred include contamination from well construction or plumbing materials (Cu, Pb, Zn – in tap waters, bottled waters and Norwegian groundwaters), water treatment (Fe, Mn – in tap- and Norwegian groundwater), bottle materials (Sb - bottled waters). The empirical CDF plots also reveal analytical issues for some elements (excessive rounding, element interferences). The best reference for natural and uncontaminated ’water’ is probably provided by the mineral water samples, representing ’deep groundwater’ at the European scale
Radiative Symmetry Breaking of the Minimal Left-Right Symmetric Model
Under the assumption of classical conformal invariance, we study the
Coleman-Weinberg symmetry breaking mechanism in the minimal left-right
symmetric model. This model is attractive as it provides a natural framework
for small neutrino masses and the restoration of parity as a good symmetry of
nature. We find that, in a large fraction of the parameter space, the parity
symmetry is maximally broken by quantum corrections in the Coleman-Weinberg
potential, which are a consequence of the conformal anomaly. As the left-right
symmetry breaking scale is connected to the Planck scale through the
logarithmic running of the dimensionless couplings of the scalar potential, a
large separation of the two scales can be dynamically generated. The symmetry
breaking dynamics of the model was studied using a renormalization group
analysis. Electroweak symmetry breaking is triggered by the breakdown of
left-right symmetry, and the left-right breaking scale is therefore expected in
the few TeV range. The phenomenological implications of the symmetry breaking
mechanism are discussed.Comment: 23 pages, 1 figure; version as published in journal; title changed,
changes in abstract, introduction and conclusion
The Flavor Structure of the Three-Site Higgsless Model
We study the flavor structure of the three-site Higgsless model and evaluate
the constraints on the model arising from flavor physics. We find that current
data constrain the model to exhibit only minimal flavor violation at tree
level. Moreover, at the one-loop level, by studying the leading chiral
logarithmic corrections to chirality-preserving Delta F = 1 and Delta F = 2
processes from new physics in the model, we show that the combination of
minimal flavor violation and ideal delocalization ensures that these
flavor-changing effects are sufficiently small that the model remains
phenomenologically viable.Comment: 23 pages, 22 pdf figures include
Z to b bbar and Chiral Currents in Higgsless Models
In this note we compute the flavor-dependent chiral-logarithmic corrections
to the decay Z to b bbar in the three site Higgsless model. We compute these
corrections diagrammatically in the "gaugeless" limit in which the electroweak
couplings vanish. We also compute the chiral-logarithmic corrections to the
decay Z to b bbar using an RGE analysis in effective field theory, and show
that the results agree. In the process of this computation, we compute the form
of the chiral current in the gaugeless limit of the three-site model, and
consider the generalization to the N-site case. We elucidate the Ward-Takahashi
identities which underlie the gaugeless limit calculation in the three-site
model, and describe how the result for the Z to b bbar amplitude is obtained in
unitary gauge in the full theory. We find that the phenomenological constraints
on the three-site Higgsless model arising from measurements of Z to b bbar are
relatively mild, requiring only that the heavy Dirac fermion be heavier than 1
TeV or so, and are satisfied automatically in the range of parameters allowed
by other precision electroweak data.Comment: 19 pages, 7 embedded eps figures (additional reference added
Minimum Degree up to Local Complementation: Bounds, Parameterized Complexity, and Exact Algorithms
The local minimum degree of a graph is the minimum degree that can be reached
by means of local complementation. For any n, there exist graphs of order n
which have a local minimum degree at least 0.189n, or at least 0.110n when
restricted to bipartite graphs. Regarding the upper bound, we show that for any
graph of order n, its local minimum degree is at most 3n/8+o(n) and n/4+o(n)
for bipartite graphs, improving the known n/2 upper bound. We also prove that
the local minimum degree is smaller than half of the vertex cover number (up to
a logarithmic term). The local minimum degree problem is NP-Complete and hard
to approximate. We show that this problem, even when restricted to bipartite
graphs, is in W[2] and FPT-equivalent to the EvenSet problem, which
W[1]-hardness is a long standing open question. Finally, we show that the local
minimum degree is computed by a O*(1.938^n)-algorithm, and a
O*(1.466^n)-algorithm for the bipartite graphs
Baryon masses at O(a^2) in chiral perturbation theory
The chiral Lagrangian for the Symanzik action through O(a^2) for baryons is
obtained. We consider two flavor unquenched and partially quenched lattice
theories, allowing for mixed actions in the latter. As an application, we
calculate masses to O(a^2) for the nucleons and deltas, and investigate the
corrections due to the violation of O(4) rotational invariance. These results
are contrasted with those in the meson sector for lattice simulations using
mixed and unmixed actions of Wilson and Ginsparg-Wilson quarks.Comment: 27 pages, 2 figures, revise
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