1,469 research outputs found
Measurement of the Transverse Single Spin Asymmetry of + + at = 200 GeV
The measurement of transverse single spin asymmetries () provides
insight into the structure of the nucleon. Several mechanisms have been
proposed that attempt to explain based on QCD, and additional
measurements of for different processes further constrain these models.
Using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC), we
study transversely polarized p+p collisions. Results from PHENIX and other
experiments show significant asymmetries in the forward region, which could be
due to contributions from both the Sivers and the Collins effects. Studying the
species as well as the kinematic dependencies of these transverse single spin
asymmetries will help to disentangle the origin of the observed asymmetries.
Therefore, measurements of with inclusive mesons at forward
rapidities are an important tool for the understanding of these asymmetries. In
2008, the PHENIX experiment collected 5.2 pb integrated luminosity in
collisions at = 200 GeV. The status of the asymmetry
analysis of mesons at forward rapidity will be shown.Comment: 4 pages, 3 figure
Study of congenital Morgagnian cataracts in Holstein calves
Cataracts are focal to diffuse opacities of the eye lens causing impaired vision or complete blindness. For bilateral congenital cataracts in Red Holsteins a perfectly cosegregating mutation within the CPAMD8 gene (CPAMD8:g.5995966C>T) has been reported. We genotyped the CPAMD8:g.5995966C>T variant in Holstein calves affected by congenital bilateral congenital cataracts, their unaffected relatives and randomly selected herd mates. Ophthalmological examinations were performed in all affected individuals to confirm a congenital cataract. Whole genome sequencing was employed to screen variants in candidate genes for the Morgagnian cataract phenotype. In the present study, 3/35 cases were confirmed as homozygous mutated and 6/14 obligate carriers. Further 7/46 unaffected animals related with these cases were heterozygous mutated for the CPAMD8:g.5995966C>T variant. However 32 cases with a congenital cataract showed the wild type for the CPAMD8 variant. We did not identify variants in the candidate genes CPAMD8 and NID1 or in their close neighborhood as strongly associated with the congenital cataract phenotype in Holstein calves with the CPAMD8 wild type. In conclusion, the CPAMD8:g.5995966C>T variant is insufficient to explain the majority of Morgagnian congenital cataract phenotypes in Holsteins. It is very likely that congenital bilateral cataracts may be genetically heterogeneous and not yet known variants in genes other than CPAMD8 and NID1 are involved
New developments in the statistical approach of parton distributions
We recall how parton distributions are constructed in a statistical physical
picture of the nucleon. The chiral properties of QCD lead to strong relations
between quarks and antiquarks distributions and the importance of the Pauli
exclusion principle is also emphasized. A global next-to-leading order QCD
analysis of unpolarized and polarized deep-inelastic scattering data allows to
determine a small number of free parameters. Some predictions are compared to
recent experimental results and we discuss the prospects of this physical
framework.Comment: 10 pages, 12 figures. Invited talk presented at the " Corfu Summer
Institute on EPP,CORFU2005, Corfu, Greece, September 4-26, 2005. To be
published in Journal of Physics, Conference Series (2006
Generation of scenarios from calibrated ensemble forecasts with a dynamic ensemble copula coupling approach
Generation of scenarios from calibrated ensemble forecasts with a dual ensemble copula coupling approach
Probabilistic forecasts in the form of ensemble of scenarios are required for
complex decision making processes. Ensemble forecasting systems provide such
products but the spatio-temporal structures of the forecast uncertainty is lost
when statistical calibration of the ensemble forecasts is applied for each lead
time and location independently. Non-parametric approaches allow the
reconstruction of spatio-temporal joint probability distributions at a low
computational cost. For example, the ensemble copula coupling (ECC) method
rebuilds the multivariate aspect of the forecast from the original ensemble
forecasts. Based on the assumption of error stationarity, parametric methods
aim to fully describe the forecast dependence structures. In this study, the
concept of ECC is combined with past data statistics in order to account for
the autocorrelation of the forecast error. The new approach, called d-ECC, is
applied to wind forecasts from the high resolution ensemble system COSMO-DE-EPS
run operationally at the German weather service. Scenarios generated by ECC and
d-ECC are compared and assessed in the form of time series by means of
multivariate verification tools and in a product oriented framework.
Verification results over a 3 month period show that the innovative method
d-ECC outperforms or performs as well as ECC in all investigated aspects
Extracting Nuclear Transparency from p-A Cross sections
We study nuclear structure effects on the transparency in high transverse
momentum and reactions. We show that in the DWIA-eikonal
approximation, even when correlations are included, one can get a factorized
expression for the transparency. This depends only on the average nucleon
density and a correlation function. We develop a technique to include
correlations in a Monte-Carlo Glauber type calculation. We compare calculations
of using the eikonal formalism and a continuous density, with a Monte Carlo
method based on discrete nucleons.Comment: 22 pages, 9 postscript figures. LaTeX with epsf styl
Measuring transversity densities in singly polarized hadron-hadron and lepton-hadron collisions
We show how the transverse polarization of a quark initiating a jet can be
probed by the azimuthal distribution of two hadrons (of large ) in the jet.
This permits a twist 2 asymmetry in hard processes when only one of the initial
particles is polarized transversely. Applications to hadron-hadron and
lepton-hadron scattering are discussed.Comment: 16 pages, LaTeX + EPSF, 2 postscript figures. PSU/TH/10
Glauber theory of initial- and final-state interactions in (p,2p) scattering
We develop the Glauber theory description of initial- and final-state
interactions (IFSI) in quasielastic A(p,2p) scattering. We study the
IFSI-distortion effects both for the inclusive and exclusive conditions. In
inclusive reaction the important new effect is an interaction between the two
sets of the trajectories which enter the calculation of IFSI-distorted one-body
density matrix for inclusive (p,2p) scattering and are connected with
incoherent elastic rescatterings of the initial and final protons on spectator
nucleons. We demonstrate that IFSI-distortions of the missing momentum
distribution are large over the whole range of missing momentum both for
inclusive and exclusive reactions and affect in a crucial way the
interpretation of the BNL data on (p,2p) scattering. Our numerical results show
that in the region of missing momentum p_{m}\lsim 100-150 MeV/c the
incoherent IFSI increase nuclear transparency by 5-10\%. The incoherent IFSI
become dominant at p_{m}\gsim 200 MeV/c.Comment: Accepted in Z. Phys.A, Latex, 26 pages, uuencoded 9 figure
Natural Color Transparency in High Energy (p,pp) Reactions
New parameter free calculations including a variety of necessary kinematic
and dynamic effects show that the results of BNL measurements are
consistent with the expectations of color transparency.Comment: latex file, 13 pages, 4 figures appended as ps files, look for "cut
here ..." 1993 Univ. of Washington preprint 404427-00-N93-1
- …
