2,728 research outputs found
Muon anomaly and a lower bound on higgs mass due to a light stabilized radion in the Randall-Sundrum model
We investigate the Randall-Sundrum model with a light stabilized radion
(required to fix the size of the extra dimension) in the light of muon
anomalous magnetic moment . Using the recent data
(obtained from the E821 experiment of the BNL collaboration) which differs by
from the Standard Model result, we obtain constraints on radion
mass \mphi and radion vev \vphi. In the presence of a radion the beta
functions \beta(\l) and of higgs quartic coupling (\l) and
top-Yukawa coupling () gets modified. We find these modified beta
functions. Using these beta functions together with the anomaly constrained
\mphi and \vphi, we obtain lower bound on higgs mass . We compare our
result with the present LEP2 bound on .Comment: Version to be appeared in IJMP
Maximum Significance at the LHC and Higgs Decays to Muons
We present a new way to define and compute the maximum significance
achievable for signal and background processes at the LHC, using all available
phase space information. As an example, we show that a light Higgs boson
produced in weak--boson fusion with a subsequent decay into muons can be
extracted from the backgrounds. The method, aimed at phenomenological studies,
can be incorporated in parton--level event generators and accommodate
parametric descriptions of detector effects for selected observables.Comment: 7 pages, 2 figures, changes to wording and new references, published
versio
Lyapunov exponent and natural invariant density determination of chaotic maps: An iterative maximum entropy ansatz
We apply the maximum entropy principle to construct the natural invariant
density and Lyapunov exponent of one-dimensional chaotic maps. Using a novel
function reconstruction technique that is based on the solution of Hausdorff
moment problem via maximizing Shannon entropy, we estimate the invariant
density and the Lyapunov exponent of nonlinear maps in one-dimension from a
knowledge of finite number of moments. The accuracy and the stability of the
algorithm are illustrated by comparing our results to a number of nonlinear
maps for which the exact analytical results are available. Furthermore, we also
consider a very complex example for which no exact analytical result for
invariant density is available. A comparison of our results to those available
in the literature is also discussed.Comment: 16 pages including 6 figure
Discovery potential of top-partners in a realistic composite Higgs model with early LHC data
Composite Higgs models provide a natural, non-supersymmetric solution to the
hierarchy problem. In these models, one or more sets of heavy top-partners are
typically introduced. Some of these new quarks can be relatively light, with a
mass of a few hundred GeV, and could be observed with the early LHC collision
data expected to be collected during 2010. We analyse in detail the collider
signatures that these new quarks can produce. We show that final states with
two (same-sign) or three leptons are the most promising discovery channels.
They can yield a 5 sigma excess over the Standard Model expectation already
with the 2010 LHC collision data. Exotic quarks of charge 5/3 are a distinctive
feature of this model. We present a new method to reconstruct their masses from
their leptonic decay without relying on jets in the final state.Comment: 28 pages 11 Figures 7 Tables, minor changes, added references,
matches published versio
3d-4f heterometallic complexes by the reduction of transition metal carbonyls with bulky Ln amidinates
The redox chemistry between divalent lanthanide complexes bearing bulky amidinate ligands has been studied with 3d transition metal carbonyl complexes (iron and cobalt). The reaction of [(DippForm)Sm(thf)] (DippForm = N,N′-bis(2,6-diisopropylphenyl)formamidinate) with [Co(CO)] resulted in the formation of a tetranuclear Sm–Co complex, [{(DippForm)Sm(thf)}{(μ-CO)Co(CO)}]. The product of the reaction of [(DippForm)Yb(thf)] and [Co(CO)] gives the dinuclear Yb–Co complex [{(DippForm)Yb(thf)}{(μ-CO)Co(CO)}] in toluene. The reaction of [(DippForm)Sm(thf)] was also carried with the neighbouring group 8 carbonyl complexes [Fe(CO)] and [Fe(CO)], resulting in a pentanuclear Sm–Fe complex, [{(DippForm)Sm}{(μ-CO)Fe(CO)}], featuring a triangular iron carbonyl cluster core
Experiment Simulation Configurations Used in DUNE CDR
The LBNF/DUNE CDR describes the proposed physics program and experimental
design at the conceptual design phase. Volume 2, entitled The Physics Program
for DUNE at LBNF, outlines the scientific objectives and describes the physics
studies that the DUNE collaboration will perform to address these objectives.
The long-baseline physics sensitivity calculations presented in the DUNE CDR
rely upon simulation of the neutrino beam line, simulation of neutrino
interactions in the far detector, and a parameterized analysis of detector
performance and systematic uncertainty. The purpose of this posting is to
provide the results of these simulations to the community to facilitate
phenomenological studies of long-baseline oscillation at LBNF/DUNE.
Additionally, this posting includes GDML of the DUNE single-phase far detector
for use in simulations. DUNE welcomes those interested in performing this work
as members of the collaboration, but also recognizes the benefit of making
these configurations readily available to the wider community.Comment: 9 pages, 4 figures, configurations in ancillary file
The effects of climatic fluctuations and extreme events on running water ecosystems
Most research on the effects of environmental change in freshwaters has focused on incremental changes in average conditions, rather than fluctuations or extreme events such as heatwaves, cold snaps, droughts, floods or wildfires, which may have even more profound consequences. Such events are commonly predicted to increase in frequency, intensity and duration with global climate change, with many systems being exposed to conditions with no recent historical precedent. We propose a mechanistic framework for predicting potential impacts of environmental fluctuations on running water ecosystems by scaling up effects of fluctuations from individuals to entire ecosystems. This framework requires integration of four key components: effects of the environment on individual metabolism, metabolic and biomechanical constraints on fluctuating species interactions, assembly dynamics of local food webs and mapping the dynamics of the meta-community onto ecosystem function. We illustrate the framework by developing a mathematical model of environmental fluctuations on dynamically assembling food webs. We highlight (currently limited) empirical evidence for emerging insights and theoretical predictions. For example, widely supported predictions about the effects of environmental fluctuations are: high vulnerability of species with high per capita metabolic demands such as large-bodied ones at the top of food webs; simplification of food web network structure and impaired energetic transfer efficiency; reduced resilience and top-down relative to bottom-up regulation of food web and ecosystem processes. We conclude by identifying key questions and challenges that need to be addressed to develop more accurate and predictive bio-assessments of the effects of fluctuations, and implications of fluctuations for management practices in an increasingly uncertain world
Further Evidence for the Decay K+ to pi+ neutrino-antineutrino
Additional evidence for the rare kaon decay K+ to pi+ neutrino-antineutrino
has been found in a new data set with comparable sensitivity to the previously
reported result. One new event was observed in the pion momentum region
examined, 211<P<229 MeV/c, bringing the total for the combined data set to two.
Including all data taken, the backgrounds were estimated to contribute 0.15 pm
0.05 events. The branching ratio is B=1.57^{+1.75}_{-0.82} 10^{-10}.Comment: 10 pages, 2 figure
Operational experience, improvements, and performance of the CDF Run II silicon vertex detector
The Collider Detector at Fermilab (CDF) pursues a broad physics program at
Fermilab's Tevatron collider. Between Run II commissioning in early 2001 and
the end of operations in September 2011, the Tevatron delivered 12 fb-1 of
integrated luminosity of p-pbar collisions at sqrt(s)=1.96 TeV. Many physics
analyses undertaken by CDF require heavy flavor tagging with large charged
particle tracking acceptance. To realize these goals, in 2001 CDF installed
eight layers of silicon microstrip detectors around its interaction region.
These detectors were designed for 2--5 years of operation, radiation doses up
to 2 Mrad (0.02 Gy), and were expected to be replaced in 2004. The sensors were
not replaced, and the Tevatron run was extended for several years beyond its
design, exposing the sensors and electronics to much higher radiation doses
than anticipated. In this paper we describe the operational challenges
encountered over the past 10 years of running the CDF silicon detectors, the
preventive measures undertaken, and the improvements made along the way to
ensure their optimal performance for collecting high quality physics data. In
addition, we describe the quantities and methods used to monitor radiation
damage in the sensors for optimal performance and summarize the detector
performance quantities important to CDF's physics program, including vertex
resolution, heavy flavor tagging, and silicon vertex trigger performance.Comment: Preprint accepted for publication in Nuclear Instruments and Methods
A (07/31/2013
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