158 research outputs found
Nuclear Physics without High-Momentum Potentials: Constructing the Nuclear Effective Interaction Directly from Scattering Observables
The traditional approach to nuclear physics encodes phase shift information
in a nucleon-nucleon (NN) potential, producing a nucleon-level interaction that
captures the sub-GeV consequences of QCD. A further reduction to the nuclear
scale is needed to produce an effective interaction for soft Hilbert spaces,
such as those employed in the shell model. Here we describe an alternative
construction of this effective interaction, from QCD directly to the nuclear
scale, that is direct and precise. This eliminates the need for constructing
and renormalizing the high-momentum NN potential. Instead, continuum phase
shifts and mixing angles are used directly at the nuclear scale. The method
exploits the analytic continuity in energy of HOBET (Harmonic-Oscillator-Based
Effective Theory) to connect bound states to continuum solutions at specific
energies. The procedure is systematic, cutoff independent, and convergent,
yielding keV accuracy at NNLO or NLO, depending on the channel. Lepage
plots are provided.Comment: 9 page
What can comparative genomics tell us about species concepts in the genus Aspergillus?
Understanding the nature of speciesâ boundaries is a fundamental
question in evolutionary biology. The availability of genomes from several
species of the genus Aspergillus allows us for the first time to
examine the demarcation of fungal species at the whole-genome level. Here, we
examine four case studies, two of which involve intraspecific comparisons,
whereas the other two deal with interspecific genomic comparisons between
closely related species. These four comparisons reveal significant variation
in the nature of species boundaries across Aspergillus. For example,
comparisons between A. fumigatus and Neosartorya fischeri
(the teleomorph of A. fischerianus) and between A. oryzae
and A. flavus suggest that measures of sequence similarity and
species-specific genes are significantly higher for the A. fumigatus
- N. fischeri pair. Importantly, the values obtained from the
comparison between A. oryzae and A. flavus are remarkably
similar to those obtained from an intra-specific comparison of A.
fumigatus strains, giving support to the proposal that A. oryzae
represents a distinct ecotype of A. flavus and not a distinct
species. We argue that genomic data can aid Aspergillus taxonomy by
serving as a source of novel and unprecedented amounts of comparative data, as
a resource for the development of additional diagnostic tools, and finally as
a knowledge database about the biological differences between strains and
species
Measurement of event-shape observables in Zââ+ââ events in pp collisions at â s=7 TeV with the ATLAS detector at the LHC
Event-shape observables measured using charged particles in inclusive
-boson events are presented, using the electron and muon decay modes of the
bosons. The measurements are based on an integrated luminosity of of proton--proton collisions recorded by the ATLAS detector at the
LHC at a centre-of-mass energy TeV. Charged-particle
distributions, excluding the lepton--antilepton pair from the -boson decay,
are measured in different ranges of transverse momentum of the boson.
Distributions include multiplicity, scalar sum of transverse momenta, beam
thrust, transverse thrust, spherocity, and -parameter, which are
in particular sensitive to properties of the underlying event at small values
of the -boson transverse momentum. The Sherpa event generator shows larger
deviations from the measured observables than Pythia8 and Herwig7. Typically,
all three Monte Carlo generators provide predictions that are in better
agreement with the data at high -boson transverse momenta than at low
-boson transverse momenta and for the observables that are less sensitive to
the number of charged particles in the event.Comment: 36 pages plus author list + cover page (54 pages total), 14 figures,
4 tables, submitted to EPJC, All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2014-0
Large expert-curated database for benchmarking document similarity detection in biomedical literature search
Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe
Leaf structure, microanalysis and characterization of the latex protein profile of Pachystroma longifolium (Nees) I.M. Jonhst. (Euphorbiaceae) in a seasonally dry Atlantic Forest
The nuclear collective motion
Current developments in nuclear structure are discussed from a theoretical perspective. First, the progress in theoretical modeling of nuclei is reviewed. This is followed by the discussion of nuclear time scales, nuclear collective modes, and nuclear deformations. Some perspectives on nuclear structure research far from stability are given. Finally, interdisciplinary aspects of the nuclear many-body problem are outlined
Measurement of the lifetime of the meson using the decay mode
The difference in total widths between the and mesons is
measured using 3.0fb of data collected by the LHCb experiment in 7 and 8
TeV centre-of-mass energy proton-proton collisions at the LHC. Through the
study of the time evolution of and
decays, the width difference is measured to be
where the first uncertainty is statistical and the second
systematic. The known lifetime of the meson is used to convert this to a
precise measurement of the lifetime,
where the first uncertainty is
statistical and the second systematic.Comment: 19 pagers, 3 figure
Measurement of the CP-violating phase in decays and limits on penguin effects
Time-dependent CP violation is measured in the channel for each resonant final state using data
collected with an integrated luminosity of 3.0 fb in collisions
using the LHCb detector. The final state with the largest rate,
, is used to measure the CP-violating angle to be . This result can be used to
limit the size of penguin amplitude contributions to CP violation measurements
in, for example, decays. Assuming approximate
SU(3) flavour symmetry and neglecting higher order diagrams, the shift in the
CP-violating phase is limited to be within the interval
[, +] at 95% confidence level. Changes to the limit
due to SU(3) symmetry breaking effects are also discussed.Comment: 18 pages, 6 figures; v2-updated from reviewers comments and added a
figur
Study of the rare B-s(0) and B-0 decays into the pi(+) pi(-) mu(+) mu(-) final state
A search for the rare decays and is performed in a data set corresponding to an integrated
luminosity of 3.0 fb collected by the LHCb detector in proton-proton
collisions at centre-of-mass energies of 7 and 8 TeV. Decay candidates with
pion pairs that have invariant mass in the range 0.5-1.3 GeV/ and with
muon pairs that do not originate from a resonance are considered. The first
observation of the decay and the first
evidence of the decay are obtained and the
branching fractions, restricted to the dipion-mass range considered, are
measured to be and
, where the third
uncertainty is due to the branching fraction of the decay , used as a normalisation.Comment: 21 pages, 3 figures, 2 Table
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