7,775 research outputs found
The Experiment: First Determination of the Weak Charge of the Proton
The Collaboration has completed a challenging measurement of the
parity-violating asymmetry in elastic electron-proton (p) scattering
at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). The
initial result reported here is extracted from the commissioning part of the
experiment, constituting about 4% of the full data set. The parity-violating
asymmetry at a low momentum transfer =0.025 GeV is = -279
35 (stat) 31 (syst) ppb, which is the smallest and most precise
asymmetry ever measured in p scattering. This result allowed the first
determination of the weak charge of the proton from a global fit of
parity-violating elastic scattering (PVES) results from nuclear targets, where
earlier data at higher constrain uncertainties of hadronic structure. The
value extracted from the global fit is (PVES) = 0.064 0.012, in
agreement with the standard model prediction (SM) = 0.0710
0.0007. The neutral weak charges of up and down quarks are extracted from a
combined fit of the PVES results with a previous atomic parity violation (APV)
measurement on Cs. The analysis of the full data is ongoing
and expected to yield a value for the asymmetry within 10 ppb of precision.
Because of the suppression of , such a high precision measurement will
place significant constraints to models of physics beyond the standard model.Comment: Talk presented at CIPANP2015. 8 pages, LaTeX, 4 eps figure
THE VALUE OF \beta FROM THE LG AND ABELL CLUSTER PECULIAR VELOCITIES
Comparing the observed peculiar velocities of the Local Group and of nearby
Abell clusters of galaxies with those predicted using linear perturbation
theory and the 3-D reconstruction algorithm of Branchini \& Plionis (1995) the
value of can be estimated. I show that the anisotropy that causes the
LG motion does not only extend to very large depths ( Mpc)
but it is also very coherent, which suggests that the value of , obtained from the LG velocity, should not be significantly
affected by cosmic variance. Comparing the Abell cluster and QDOT galaxy
dipoles in real space their relative biasing factor are estimated to be
. Finally, using a suitable set of available cluster
peculiar velocities I obtain a somewhat lower value of but with a large uncertainty () when weighted by the large
observational errors.Comment: 4 pages self unpacking compressed postscript file containing figures.
Contribution to the XVth MORIOND astrophysics meeting (March 1995
Acceptance Rates in Physical Review Letters: No Seasonal Bias
Are editorial decisions biased? A recent discussion in Learned Publishing has
focused on one aspect of potential bias in editorial decisions, namely seasonal
(e.g., monthly) variations in acceptance rates of research journals. In this
letter, we contribute to the discussion by analyzing data from Physical Review
Letters (PRL), a journal published by the American Physical Society. We studied
the 190,106 papers submitted to PRL from January 1990 until September 2012. No
statistically significant variations were found in the monthly acceptance
rates. We conclude that the time of year that the authors of a paper submit
their work to PRL has no effect on the fate of the paper through the review
process.Comment: Scheduled to appear in Learned Publishin
The Large-Scale Environment of Groups & Clusters of Galaxies
It appears that the dynamical status of clusters and groups of galaxies is
related to the large-scale structure of the Universe. A few interesting trends
have been established:
(1) The Cluster Substructure - Alignment Connection, by which clusters show a
strong correlation between their tendency to be aligned with their neighbors
and their dynamical state (as indicated by the existence of significant
substructres). (2) The Cluster Dynamics -Cluster Clustering Connection, by
which dynamically young clusters are more clustered than the overall cluster
population. (3) The Cluster- Supercluster Alignment Connection, by which
clusters of galaxies show a statistical significant tendency to be aligned with
the projected major axis orientation of their parent supercluster. (4) The
Galaxy Alignment - Cluster Dynamics Connection, by which red-sequence cluster
bright galaxies show a significant trend to be aligned with their parent
cluster major axis, especially in dynamically young clusters. (5) The Group
Richness - Shape Connection, by which groups of galaxies are flatter the poorer
they are.
These are strong indications that clusters develop in a hierarchical fashion
by anisotropic merging of smaller units along the large-scale filamentary
structures within which they are embedded.Comment: Invited Talk in IAU colloquium 195 (Torino, March 12-16 2004
Highlighting Impact and the Impact of Highlighting: PRB Editors' Suggestions
Associate Editor Manolis Antonoyiannakis discusses the highlighting, as
Editors' Suggestions, of a small percentage of the papers published each week.
We highlight papers primarily for their importance and impact in their
respective fields, or because we find them particularly interesting or elegant.
It turns out that the additional layer of scrutiny involved in the selection of
papers as Editors' Suggestions is associated with a significantly elevated and
sustained citation impact.Comment: Editoria
The Cluster Substructure - Alignment Connection
Using the APM cluster data we investigate whether the dynamical status of
clusters is related to the large-scale structure of the Universe. We find that
cluster substructure is strongly correlated with the tendency of clusters to be
aligned with their nearest neighbour and in general with the nearby clusters
that belong to the same supercluster. Furthermore, dynamically young clusters
are more clustered than the overall cluster population. These are strong
indications that cluster develop in a hierarchical fashion by anisotropy
merging along the large-scale filamentary superclusters within which they are
embedded.Comment: To appear in the Proceedings of `Galaxy Clusters and the High
Redshift Universe Observed in X-rays', XXIth Moriond Astrophysics Meeting
(March 2001), Eds. Doris Neumann et a
Representations of the Mapping Class Group of the Two Punctured Torus on the Space of \hat {sl}(2,C) Spin1/2-Spin1/2 Kac-Moody Blocks
The integral representations of the Spin 1/2 - Spin 1/2
Kac-Moody Blocks on the torus, arising from the free field representation of
the Kac-Moody algebra of Wakimoto and Bernard and Felder, are
used to derive an infinite class of representations of the mapping class group
of the two punctured torus.Comment: 13 pages LaTeX, requires epsf, replaced TeX symbols in abstrac
Method and apparatus for automatic text input insertion in digital devices with a restricted number of keys
A device which contains number of symbol input keys, where the number of
available keys is less than the number of symbols of an alphabet of any given
language, screen, and dynamic reordering table of the symbols which are mapped
onto those keys, according to a disambiguation method based on the previously
entered symbols. The device incorporates a previously entered keystrokes
tracking mechanism, and the key selected by the user detector, as well as a
mechanism to select the dynamic symbol reordering mapped onto this key
according to the information contained to the reordering table. The reordering
table occurs from a disambiguation method which reorders the symbol appearance.
The reordering information occurs from Bayesian Belief network construction and
training from text corpora of the specific language.Comment: European patent offic
Incomplete Information in RDF
We extend RDF with the ability to represent property values that exist, but
are unknown or partially known, using constraints. Following ideas from the
incomplete information literature, we develop a semantics for this extension of
RDF, called RDFi, and study SPARQL query evaluation in this framework
The Substructure-Alignment Connection
Using a sample of 903 APM clusters we investigate whether their dynamical
status, as evidenced by the presence of significant substructures, is related
to the large-scale structure of the Universe. We find that the cluster
dynamical activity is strongly correlated with the tendency of clusters to be
aligned with their nearest neighbour and in general with the nearby clusters
that belong to the same supercluster. Furthermore, dynamically active clusters
are more clustered than the overall cluster population. These are strong
indications that clusters develop in a hierarchical fashion by anisotropic
merging along the large-scale filaments within which they are embedded.Comment: 5 pages, accepted for publication in MNRAS pink page
- …