3,047 research outputs found
Full one-loop electroweak corrections to e+e- to 3 jets at linear colliders
We describe the impact of the full one-loop electroweak terms of O(alpha_s
alpha_EM^3) entering the electron-positron into three-jet cross-section from
sqrt(s)=M_Z to TeV scale energies. We include both factorisable and
non-factorisable virtual corrections and photon bremsstrahlung. Their
importance for the measurement of alpha_S from jet rates and shape variables is
explained qualitatively and illustrated quantitatively, also in presence of
b-tagging.Comment: 6 pages, to appear in the proceedings of the workshop "LC09 -- e+e-
Physics at the TeV scale and the Dark Matter Connection", 21-24 September
2009, Perugia (Italy). Minor corrections, references added
Is the anomalous decay ratio of D_{sJ}(2632) due to isospin breaking?
Quark pair annihilation into gluons is suppressed at large momenta due to the
asymptotic freedom. As a consequence, mass eigenvalues of heavy states should
be almost diagonal with respect to up and down quark masses, thereby breaking
isospin. We suggest the particle observed by the SELEX Collaboration,
D_{sJ}(2632) to be to a good extent a [cd][dbar sbar] state, which would
explain why its D^0 K^+ mode is anomalously suppressed with respect to D_s eta.
Predictions for the rates of the yet unobserved modes D_s pi^0 and D^+ K^0 are
given.Comment: 3 pages, 1 figur
Higgs decay into four charged leptons in the presence of dimension-six operators
We study the indirect effects of New Physics in the Higgs decay into four
charged leptons, using an Effective Field Theory (EFT) approach to Higgs
interactions. We evaluate the deviations induced by the EFT dimension-six
operators in observables like partial decay width and various kinematic
distributions, including angular observables, and compare them with the
contribution of the full SM electroweak corrections. The calculation is
implemented in an improved version of the event generator Hto4l, which can
provide predictions in terms of different EFT-bases and is available for data
analysis at the LHC. We also perform a phenomenological study in order to
assess the benefits coming from the inclusion of differential information in
the future analyses of very precise data which will be collected during the
high luminosity phase of the LHC.Comment: 31 pages, 8 figures, 1 table. Version to appear on JHEP, expanded
phenomenological section including an analysis for HL-LH
A new look at scalar mesons
Light scalar mesons are found to fit rather well a diquark-antidiquark
description. The resulting nonet obeys mass formulae which respect, to a good
extent, the OZI rule. OZI allowed strong decays are reasonably reproduced by a
single amplitude describing the switch of a qbar-q pair, which transforms the
state into two colourless pseudoscalar mesons. Predicted heavy states with one
or more quarks replaced by charm or beauty are briefly described; they should
give rise to narrow states with exotic quantum numbers.Comment: 4 pages, 1 figure, misprints corrected, references added, accepted
for publication in Phys. Rev. Let
DAMPening Inflammation by Modulating TLR Signalling
Damage-associated molecular patterns (DAMPs) include endogenous intracellular molecules released by activated or necrotic cells and extracellular matrix (ECM) molecules that are upregulated upon injury or degraded following tissue damage. DAMPs are vital danger signals that alert our immune system to tissue damage upon both infectious and sterile insult. DAMP activation of Toll-like receptors (TLRs) induces inflammatory gene expression to mediate tissue repair. However, DAMPs have also been implicated in diseases where excessive inflammation plays a key role in pathogenesis, including rheumatoid arthritis (RA), cancer, and atherosclerosis. TLR activation by DAMPs may initiate positive feedback loops where increasing tissue damage perpetuates pro-inflammatory responses leading to chronic inflammation. Here we explore the current knowledge about distinct signalling cascades resulting from self TLR activation. We also discuss the involvement of endogenous TLR activators in disease and highlight how specifically targeting DAMPs may yield therapies that do not globally suppress the immune system
Electronic, optical and thermal properties of the hexagonal and fcc Ge2Sb2Te5 chalcogenide from first-principle calculations
We present a comprehensive computational study on the properties of
face-centered cubic and hexagonal chalcogenide Ge2Sb2Te5. We calculate the
electronic structure using density functional theory (DFT); the obtained
density of states (DOS) compares favorably with experiments, also looking
suitable for transport analysis. Optical constants including refraction index
and absorption coefficient capture major experimental features, aside from an
energy shift owed to an underestimate of the band gap that is typical of DFT
calculations. We also compute the phonon DOS for the hexagonal phase, obtaining
a speed of sound and thermal conductivity in good agreement with the
experimental lattice contribution. The calculated heat capacity reaches ~ 1.4 x
106 J/(m3 K) at high temperature, in agreement with experimental data, and
provides insight into the low-temperature range (< 150 K), where data are
unavailable.Comment: 19 pages, 8 figure
Diquark-Antidiquarks with Hidden or Open Charm and the Nature of X(3872)
Heavy-light diquarks can be the building blocks of a rich spectrum of states
which can accommodate some of the newly observed charmonium-like resonances not
fitting a pure c-cbar assignment. We examine this possibility for hidden and
open charm diquark-antidiquark states deducing spectra from constituent quark
masses and spin-spin interactions. Taking the X(3872) as input we predict the
existence of a 2++ state that can be associated to the X(3940) observed by
Belle and re-examine the state claimed by SELEX, X(2632). The possible
assignment of the previously discovered states D_s(2317) and D_s(2457) is
discussed. We predict X(3872) to be made of two components with a mass
difference related to (m_u-m_d) and discuss the production of X(3872) and of
its charged partner X^(+-) in the weak decays of B^(+,0).Comment: 11 pages, 2 figures, revtex, minor typos correcte
The systematic integration of Human Factors into safety analyses: an integrated engineering approach
The performance of the human reliability analysis (HRA) and integration of its outcomes into quantitative risk assessment schemes remains quite a difficult and complex task to perform. Even worse is the assessment of organisational reliability assessment. The reasons of this difficulty mainly lay on the absence of a generically accepted paradigm that enables engineers to include systematically human and organisational factors (H&OF) into the analysis. Broadly speaking, engineering approaches very often account for error of omission forgetting the errors of commission (EOC), and, on top of that, they do not make any macro distinction between pre- and post-initiating human failures. This paper offers a paradigm on how to integrate H&OF into safety analysis by means of the recursive operability analysis (ROA), which has been adapted to accommodate H&OF, and renamed integrated recursive operability analysis (IROA). By means of a practical example, the method will illustrate how to account for H&OF in a systematic and consistent manner using an engineering approach. The paper will even provide a paradigm for the construction of integrated fault trees consistent with the IROA framewor
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