1,333 research outputs found
Quark Mixing, CKM Unitarity
In the Standard Model of elementary particles, quark-mixing is expressed in
terms of a 3 x 3 unitary matrix V, the so called Cabibbo-Kobayashi-Maskawa
(CKM) matrix. Significant unitarity checks are so far possible for the first
row of this matrix. This article reviews the experimental and theoretical
information on these matrix elements. On the experimental side, we find a 2.2
sigma to 2.7 sigma deviation from unitarity, which conflicts with the Standard
Model.Comment: accepted by EPJ
Fast computation by block permanents of cumulative distribution functions of order statistics from several populations
The joint cumulative distribution function for order statistics arising from
several different populations is given in terms of the distribution function of
the populations. The computational cost of the formula in the case of two
populations is still exponential in the worst case, but it is a dramatic
improvement compared to the general formula by Bapat and Beg. In the case when
only the joint distribution function of a subset of the order statistics of
fixed size is needed, the complexity is polynomial, for the case of two
populations.Comment: 21 pages, 3 figure
Not all surveillance data are created equal—A multi‐method dynamic occupancy approach to determine rabies elimination from wildlife
1. A necessary component of elimination programmes for wildlife disease is effective surveillance. The ability to distinguish between disease freedom and non‐detection can mean the difference between a successful elimination campaign and new epizootics. Understanding the contribution of different surveillance methods helps to optimize and better allocate effort and develop more effective surveillance programmes.
2. We evaluated the probability of rabies virus elimination (disease freedom) in an enzootic area with active management using dynamic occupancy modelling of 10 years of raccoon rabies virus (RABV) surveillance data (2006–2015) collected from three states in the eastern United States. We estimated detection probability of RABV cases for each surveillance method (e.g. strange acting reports, roadkill, surveillance‐trapped animals, nuisance animals and public health samples) used by the USDA National Rabies Management Program.
3. Strange acting, found dead and public health animals were the most likely to detect RABV when it was present, and generally detectability was higher in fall– winter compared to spring–summer. Found dead animals in fall–winter had the highest detection at 0.33 (95% CI: 0.20, 0.48). Nuisance animals had the lowest detection probabilities (~0.02).
4. Areas with oral rabies vaccination (ORV) management had reduced occurrence probability compared to enzootic areas without ORV management. RABV occurrence was positively associated with deciduous and mixed forests and medium to high developed areas, which are also areas with higher raccoon (Procyon lotor) densities. By combining occupancy and detection estimates we can create a probability of elimination surface that can be updated seasonally to provide guidance on areas managed for wildlife disease.
5. Synthesis and applications. Wildlife disease surveillance is often comprised of a combination of targeted and convenience‐based methods. Using a multi‐method analytical approach allows us to compare the relative strengths of these methods, providing guidance on resource allocation for surveillance actions. Applying this multi‐method approach in conjunction with dynamic occupancy analyses better informs management decisions by understanding ecological drivers of disease occurrence
Studies of parton thermalization at RHIC
We consider the evolution of a parton system which is formed in the central
region just after a relativistic heavy ion collision. The parton consist of
mostly gluons, minijets, which are produced by elastic scattering between
constituent partons of the colliding nuclei. We assume the system can be
described by a semi-classical Boltzmann transport equation, which we solve by
means of the test particle Monte-Carlo method including retardation. The
partons proliferate via secondary radiative processes until the
thermalization is reached for some assumptions. The extended system is
thermalized at about fm/ with MeV and stays in equilibrium
for about 2 fm/ with breaking temperature MeV in the rapidity
central region.Comment: 14 page
Towards a rhizomatic understanding of the desistance journey
Although the ‘desistance as a (zigzag) journey’ metaphor has proved useful in terms of translating theory into practice, this article makes the case that it is insufficient for conveying the truly complex, social, unpredictable and ‘messy’ process of desistance from crime. The article uses what we know about the process of desistance to discuss the utility of Deleuze and Guattari’s (2013) rhizomatic theory in recasting the desistance journey metaphor. In doing so it is suggested that the desistance journey should be understood in terms of its endless and multiplicitous nature, a symbol of metamorphosis, and it argues that our focus should be on understanding the ‘desister as nomad’. This, the article concludes, holds important ramifications for the way in which we understand and implement desistance-focused practice in the criminal justice system
Commissioning of the vacuum system of the KATRIN Main Spectrometer
The KATRIN experiment will probe the neutrino mass by measuring the
beta-electron energy spectrum near the endpoint of tritium beta-decay. An
integral energy analysis will be performed by an electro-static spectrometer
(Main Spectrometer), an ultra-high vacuum vessel with a length of 23.2 m, a
volume of 1240 m^3, and a complex inner electrode system with about 120000
individual parts. The strong magnetic field that guides the beta-electrons is
provided by super-conducting solenoids at both ends of the spectrometer. Its
influence on turbo-molecular pumps and vacuum gauges had to be considered. A
system consisting of 6 turbo-molecular pumps and 3 km of non-evaporable getter
strips has been deployed and was tested during the commissioning of the
spectrometer. In this paper the configuration, the commissioning with bake-out
at 300{\deg}C, and the performance of this system are presented in detail. The
vacuum system has to maintain a pressure in the 10^{-11} mbar range. It is
demonstrated that the performance of the system is already close to these
stringent functional requirements for the KATRIN experiment, which will start
at the end of 2016.Comment: submitted for publication in JINST, 39 pages, 15 figure
Interaction of a TeV Scale Black Hole with the Quark-Gluon Plasma at LHC
If the fundamental Planck scale is near a TeV, then parton collisions with
high enough center-of-mass energy should produce black holes. The production
rate for such black holes has been extensively studied for the case of a
proton-proton collision at \sqrt s = 14 TeV and for a lead-lead collision at
\sqrt s = 5.5 TeV at LHC. As the parton energy density is much higher at
lead-lead collisions than in pp collisions at LHC, one natural question is
whether the produced black holes will be able to absorb the partons formed in
the lead-lead collisions and eventually `eat' the quark-gluon plasma formed at
LHC. In this paper, we make a quantitative analysis of this possibility and
find that since the energy density of partons formed in lead-lead collisions at
LHC is about 500 GeV/fm^3, the rate of absorption for one of these black holes
is much smaller than the rate of evaporation. Hence, we argue that black holes
formed in such collisions will decay very quickly, and will not absorb very
many nearby partons. More precisely, we show that for the black hole mass to
increase via parton absorption at the LHC the typical energy density of quarks
and gluons should be of the order of 10^{10} GeV/fm^3. As LHC will not be able
to produce such a high energy density partonic system, the black hole will not
be able to absorb a sufficient number of nearby partons before it decays. The
typical life time of the black hole formed at LHC is found to be a small
fraction of a fm/c.Comment: 7 pages latex (double column), 3 eps figure
Operator Product Expansion and Quark-Hadron Duality: Facts and Riddles
We review the status of the practical operator product expansion (OPE), when
applied to two-point correlators of QCD currents which interpolate to mesonic
resonances, in view of the violations of local quark-hadron duality. Covered
topics are: a mini-review of mesonic QCD sum rules in vacuum, at finite
temperature, or at finite baryon density, a comparison of model calculations of
current-current correlation functions in 2D and 4D with the OPE expression, a
discussion of meson distribution amplitudes in the light of nonperturbatively
nonlocal modifications of the OPE, and a reorganization of the OPE which
(partially) resums powers of covariant derivatives.Comment: now 68 pages, 29 figures (1 figure added), habilitation thesis, mild
restructuring, typos corrected, about 30 references and corresponding text
added, version to be published in Prog. Part. Nucl. Phy
Technological Change in Economic Models of Environmental Policy: A Survey
This paper provides an overview of the treatment of technological change in economic models of environmental policy. Numerous economic modeling studies have confirmed the sensitivity of mid- and long-run climate change mitigation cost and benefit projections to assumptions about technology costs. In general, technical progress is considered to be a noneconomic, exogenous variable in global climate change modeling. However, there is overwhelming evidence that technological change is not an exogenous variable but to an important degree endogenous, induced by needs and pressures. Hence, some environmenteconomy models treat technological change as endogenous, responding to socio-economic variables. Three main elements in models of technological innovation are: (i) corporate investment in research and development, (ii) spillovers from R&D, and (iii) technology learning, especially learning-by-doing. The incorporation of induced technological change in different types of environmental-economic models tends to reduce the costs of environmental policy, accelerates abatement and may lead to positive spillover and negative leakage
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