Bulletin of the American Physical Society
2006 APS April Meeting
Saturday–Tuesday, April 22–25, 2006; Dallas, TX
Session P8: Minisymposium: Parton Distributions at Larger X : Data and Challenges |
Hide Abstracts |
Sponsoring Units: DNP Chair: Cynthia Keppel, Hampton University/Jefferson Lab Room: Hyatt Regency Dallas Cumberland A |
Monday, April 24, 2006 10:45AM - 11:21AM |
P8.00001: The CTEQ Global Fitting Project and the Impact of PDF's at Large-x Invited Speaker: The status of CTEQ global fitting activities is reviewed with a special emphasis on the large-x region. The impact of new data sets included in the fits will be discussed along with the importance of reducing the errors on the distribution functions at large values of x. Specific topics include nuclear corrections, next-to-next-to leading order evolution, and recent applications of resummation techniques. [Preview Abstract] |
Monday, April 24, 2006 11:21AM - 11:33AM |
P8.00002: QCD results from NuTeV and some remarks on target mass corrections Voica Radescu NuTeV is a precision Neutrino-Nucleon DIS experiment that took place at Fermilab in the 1996-97 fixed target run. Its unique design allowed us to obtain high statistics samples of separate $\nu$ and $\overline{\nu}$ beams. The kinematic range in $x$ goes from $0.01> x> 0.8$ with an average $Q^2\sim 20~GeV^2 $. We report here a new determination of $\alpha_S$ from scaling violations of the structure functions $F_2$ and $xF_3$ using NLO QCD models. The fit requires a correction for the target mass effect. This correction proved to create some confusion and we will also discuss this. [Preview Abstract] |
Monday, April 24, 2006 11:33AM - 11:45AM |
P8.00003: Neutron Structure Functions at Large x: Status of the BONUS Experiment Ioana Niculescu While an impressive amount of high quality nucleon structure function data exists, there nonetheless remain unmeasured areas. Most notably, the lack of a neutron target has made direct comparisons between proton and neutron structure functions nearly impossible both in the resonance region and at large x. The ``Barely off Shell Nucleon Structure (BONUS) Collaboration'' has constructed a novel radial time projection chamber (RTPC) that uses a gas electron multiplier readout to detect slow, backward- going spectator protons resulting from electron-deuteron interactions. Spectator protons in the RTPC are detected in coincidence with electrons in the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B at Jefferson Lab, thereby ensuring an inclusive electron-neutron scattering event. Two months of data (roughly 900 million triggers) were collected in late 2005 at beam energies from 1.1 to 5.3 GeV. Preliminary neutron elastic and resonance results will be discussed, focusing on the performance of the RTPC in CLAS. [Preview Abstract] |
Monday, April 24, 2006 11:45AM - 11:57AM |
P8.00004: Probing the Large-$x$ Structure of the Proton with Drell-Yan Scattering at Fermilab Paul E Reimer The Drell-Yan reaction can be used to probe the parton distribution of the interaction hadrons. In a fixed target environment, where the detector acceptance selects only large-$x_F$ events, Drell-Yan probes the high-$x$ (Bjorken-$x$) valence distributions of the beam and the low- to intermediate-$x$ sea antiquark distributions of the target. Fermilab E866/NuSea has measured the Drell-Yan absolute cross section of 800 GeV/c protons on hydrogen and deuterium targets. These data are the first measurements of the Drell-Yan cross section in $pp$ collisions over a broad kinematic region and the most extensive study to date of the Drell-Yan cross section in $pd$ collisions. The absolute cross sections, with full radiative corrections, will be presented and comparisons made with with next-to-leading order calculations based on modern parton distributions. The results show that recent global parton distribution fits provide a good description of the light antiquark sea in the nucleon over the range $0.03 < x_\textrm{target} < 0.15$. When projected against $x_\textrm{beam}$ the data indicate that most modern parton distributions appear to overestimate the valence parton distributions at large-$x$. We plan to extend these studies in Fermilab E906, which will use a 120 GeV/c proton beam from the Fermilab Main Injector to collect better statistics at even larger values of $x_\textrm{beam}$. [Preview Abstract] |
Monday, April 24, 2006 11:57AM - 12:09PM |
P8.00005: Measurements of Hydrogen and Deuterium Inclusive Resonance Cross Sections at Intermediate Q$^{2}$ for Parton-Hadron Duality Studies. Simona Malace Results from the Jefferson Lab E00-116 experiment that ran in Summer of 2003 will be presented. The experiment extended to higher Q$^{2}$ the precision measurements of inclusive nucleon resonance electroproduction cross sections from hydrogen and deuterium targets. The data cover a kinematic range of (3.9 -- 7.2) GeV$^{2}$ in Q$^{2}$ and (0.5 -- 0.9) in x, and will be used in conjunction with the elastic and inelastic data for precision experimental tests of parton-hadron (Bloom-Gilman) duality in the structure functions. E00-116 data that access the high x region will also be used to constrain higher moments of the structure functions and to extract matrix elements of higher-twist operators. This data will also provide a constraint for the F$_{2}^{d}$/F$_{2}^{p}$ ratio and therefore possibly be of utility in reducing the uncertainties on pdf curves at high x. [Preview Abstract] |
Monday, April 24, 2006 12:09PM - 12:21PM |
P8.00006: Monitoring the Transition from Perturbative to Non-perturbative QCD through Parton-Hadron Duality Simonetta Liuti Parton-hadron duality, or the similarity between hadronic cross sections in the deep inelastic region and in the resonance region, encompasses a range of phenomena where one expects to observe a trasmogrification from partonic to hadronic degrees of freedom. A fully satisfactory theoretical description of this phenomenon, that became to be accepted as a ``natural'' feature of hadronic interactions, is still nowadays very difficult to obtain. In this contribution, by conducting an analysis of the most recent polarized and unpolarized inclusive electron scattering data, we present evidence that standard perturbative QCD approaches might not be adequate in order to describe parton-hadron duality. In particular, we unravel a discrepancy in the behavior of the extracted power corrections in the DIS and resonance regions, respectively. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700