2,185 research outputs found
Light scalar at LHC: the Higgs or the dilaton?
It is likely that the LHC will observe a color- and charge-neutral scalar
whose decays are consistent with those of the Standard Model (SM) Higgs boson.
The Higgs interpretation of such a discovery is not the only possibility. For
example, electroweak symmetry breaking (EWSB) could be triggered by a
spontaneously broken, nearly conformal sector. The spectrum of states at the
electroweak scale would then contain a narrow scalar resonance, the
pseudo-Goldstone boson of conformal symmetry breaking, with Higgs-like
properties. If the conformal sector is strongly coupled, this pseudo-dilaton
may be the only new state accessible at high energy colliders. We discuss the
prospects for distinguishing this mode from a minimal Higgs boson at the LHC
and ILC. The main discriminants between the two scenarios are (1) cubic
self-interactions and (2) a potential enhancement of couplings to massless SM
gauge bosons. A particularly interesting situation arises when the scale f of
conformal symmetry breaking is approximately the electroweak scale v~246 GeV.
Although in this case the LHC may not be able to tell apart a pseudo-dilaton
from the Higgs boson, the self-interactions differ in a way that depends only
on the scaling dimension of certain operators in the conformal sector. This
opens the possibility of using dilaton pair production at future colliders as a
probe of EWSB induced by nearly conformal new physics.Comment: 7 pages, LaTe
Standard Model couplings and collider signatures of a light scalar
The electroweak symmetry breaking (EWSB) sector of the Standard Model can be
far richer and more interesting than the usual single scalar doublet model. We
explore scenarios where the EWSB sector is nearly scale invariant and
consequently gives rise to a light CP even scalar particle. The one-doublet SM
is in that category, as are many other models with either weakly or strongly
coupled sectors that trigger EWSB. We study the couplings of the light scalar
to the SM particles that can arise from the explicit breaking of scale
invariance focusing on the possible differences with the minimal SM. The
couplings of the light scalar to light fermions, as well as to the massless
gauge bosons, can be significantly enhanced. We find possible new discovery
channels due to the decays of the conformal scalar into e^+e^- and mu^+mu^-
pairs as well as new production channels via light quark annihilation.Comment: 10 pages, 7 figure
Contamination
Soil contamination occurs when substances are added to soil, resulting in increases in concentrations
above background or reference levels. Pollution may follow from contamination when contaminants
are present in amounts that are detrimental to soil quality and become harmful to the environment or
human health. Contamination can occur via a range of pathways including direct application to land and
indirect application from atmospheric deposition.
Contamination was identified by SEPA (2001) as a significant threat to soil quality in many parts of
Scotland. Towers et al. (2006) identified four principal contamination threats to Scottish soils: acidification;
eutrophication; metals; and pesticides. The Scottish Soil Framework (Scottish Government, 2009) set out
the potential impact of these threats on the principal soil functions.
Severe contamination can lead to “contaminated land” [as defined under Part IIA of the Environmental
Protection Act (1990)]. This report does not consider the state and impacts of contaminated land on
the wider environment in detail. For further information on contaminated land, see ‘Dealing with Land
Contamination in Scotland’ (SEPA, 2009).
This chapter considers the causes of soil contamination and their environmental and socio-economic
impacts before going on to discuss the status of, and trends in, levels of contaminants in Scotland’s soils
Grain and plant protein types fed to weaned piglets influence the apparent digestibility of carbohydrates and crude protein when measured at the terminal ileum
Diets based on cooked white rice fed to weaned piglets have a higher apparent ileal digestibility of starch than diets based on wheat (Pluske et al., 2007). The diets based on cooked white rice have used predominately animal sources of protein, however in Europe these are banned or excluded by retailer's specifications (except for milk proteins), and plant proteins are widely used instead. This study examined the interactive effects of cereal types and plant protein types on the apparent ileal digestibility of protein and carbohydrates to test the proposition that suitable sources of plant protein could ensure high digestibility coefficients in the small intestine
Investigating uptake of N2O in agricultural soils using a high-precision dynamic chamber method
Uptake (or negative flux) of nitrous oxide (N2O)in agricultural soils is a controversial issue which has proved
difficult to investigate in the past due to constraints such
as instrumental precision and methodological uncertainties.
Using a recently developed high-precision quantum cascade
laser gas analyser combined with a closed dynamic chamber,
a well-defined detection limit of 4 μg N2O-N m could
be achieved for individual soil flux measurements. 1220 mea-
surements of N2O flux were made from a variety of UK
soils using this method, of which 115 indicated uptake by the soil (i.e. a negative flux in the micrometeorological sign convention). Only four of these apparently negative fluxes were greater than the detection limit of the method, which suggests that the vast majority of reported negative fluxes from such measurements are actually due to instrument noise. As such, we suggest that the bulk of negative N2O fluxes reported for agricultural fields are most likely due to limits in detection of a particular flux measurement methodology and not a result of microbiological activity consuming atmospheric N2O
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