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Gluon density in nuclei

Description: In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab.
Date: October 1996
Creator: Ayala, A. L.; Ducati, M. B. G. & Levin, E. M.
Partner: UNT Libraries Government Documents Department

Theoretical description of heavy quark production in DIS

Description: We present results from a new event-generator Monte Carlo program for semi- inclusive DIS heavy quark production computed in a composite 3-flavor/4-flavor scheme, which is applicable over a wider range of energy scales than existing calculations. We compare the semi-inclusive distributions in p{sub t}, Q{sup 2} and W at O ({alpha}{sup 1}{sub s}) with recent HERA results. We also compare the inclusive F{sup charm}{sub 2} with the data and the existing O ({alpha}{sup 2}{sub s}) 3-flavor scheme calculation. Both calculations agree will with current HERA data, but the resummed O ({alpha}{sup 1}{sub s}) composite scheme calculation is simpler and more efficient by an order of magnitude.
Date: July 1, 1998
Creator: Amundson, J., FERMI
Partner: UNT Libraries Government Documents Department

Effective field theory for the small-x evolution

Description: The small-x behavior of structure functions in the saturation region is determined by the non-linear generalization of the BFKL equation. I suggest the effective field theory for the small-x evolution which solves formally this equation. The result is the 2+1 functional integral for the structure functions at small x.
Date: May 1, 2001
Creator: Balitsky, Ian
Partner: UNT Libraries Government Documents Department

Hard diffraction

Description: An introduction to the rapidly developing subject of diffractive processes containing jets is given, with emphasis on an s-channel picture of the dynamics.
Date: March 1, 1994
Creator: Bjorken, J.D.
Partner: UNT Libraries Government Documents Department

A Measurement of {chi}F{nu over 3}-{chi}F{nubar over 3} and R with the CCFR Detector

Description: We report on a measurement of the neutrino-nucleon and antineutrino-nucleon differential cross sections in the CCFR detector. The measurement of the differential cross sections over a wide range of energies allows {Delta}xF<sub>3</sub> = xF<sup>{nu}</sup><sub>3</sub> -xF<sup>{anti {nu}}</sup><sub>3</sub> and R to be extracted. {Delta}xF</sub>3</sub> is related to the difference between the contributions of the strange and charm seas in the nucleon to production of massive charm quark. The results for {Delta}xF</sub>3</sub> are compared to various massive charm NLO QCD models. The Q&sup2; dependence of R for x < 0.1 has been measured for the first time.
Date: July 12, 1999
Creator: al., U.K. Yang et
Partner: UNT Libraries Government Documents Department

Antiquark distributions in the proton

Description: This is the final report of a three-year Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The study of quark and antiquark distributions in the nucleon has been a major endeavor in nuclear and particle physics. Results from a recent deep-inelastic scattering experiment suggest the surprising possibility that the up and down antiquark distributions in the proton are not symmetric. A sensitive and direct determination of the antiquark distributions in the proton can be made by comparing the Drell-Yan cross sections on hydrogen versus deuterium targets. The authors have proposed a new experiment (E866) at Fermilab to carry out such measurements. E866 has been taking data since September 1996. Preliminary results show that the apparatus is working very well. The authors anticipate having seven months of beam in 1997, which would allow them to achieve the sensitivities for a definitive measurement of flavor symmetry of sea quarks in the proton.
Date: July 1, 1997
Creator: Brooks, M.; Carey, T. & Garvey, G.
Partner: UNT Libraries Government Documents Department

Relativistic Theory of Few Body Systems

Description: Very significant advances have been made in the relativistic theory of few body systems since I visited Peter Sauer and his group in Hannover in 1983. This talk provides an opportunity to review the progress in this field since then. Different methods for the relativistic calculation of few nucleon systems are briefly described. As an example, seven relativistic calculations of the deuteron elastic structure functions, A, B, and T{sub 20}, are compared. The covariant SPECTATOR {copyright} theory, among the more successful and complete of these methods, is described in more detail.
Date: November 1, 2002
Creator: Gross, Franz
Partner: UNT Libraries Government Documents Department

Quark-Hadron Duality in Inclusive Electron-Nucleus Scattering

Description: Recent inclusive electron-nucleus scattering data have been utilized for precision tests of quark-hadron duality. The data are in the resonance and quasielastic regions and cover a range in Q{sup 2} from 0.5 to 7 (GeV/c){sup 2}. The Q{sup 2} dependence of the moments of the F{sub 2} structure function were investigated and indicate that duality holds for nuclei, even at low Q{sup 2}.
Date: March 1, 2002
Creator: Arrington, J.; Crowder, J.; Ent, R.; Keppel, C. & Niculescu, I.
Partner: UNT Libraries Government Documents Department

Test of structure functions using lepton pairs: W-charge asymmetry and Drell-Yan production at CDF

Description: The charge asymmetry of leptons from W-bosons and the Drell-Yan cross section of massive charged lepton pairs from {gamma}*/Z-bosons produced in p{anti p} collisions are measured using 110 pb{sup -1} of collisions taken by the Collider Detector at Fermilab (CDF) during 1992-95. The W-asymmetry measurement provides a precise constraint of the slope of the quark distribution ratio, d(x)/u(x), over the x range of 0.006 to 0.34. The Drell-Yan measurement spans the mass range of 11 to 500 GeV/c{sup 2}, and QCD calculations using recent parton distribution functions are in good agreement with it.
Date: October 1, 1998
Creator: Sakumoto, W.
Partner: UNT Libraries Government Documents Department

Parton distributions from SMC and SLAC data

Description: We have extracted spin-weighted parton distributions in a proton from recent data at CERN and SLAC. The valence, sea quark and Antiquark spin-weighted distributions are determined separately. The data are all consistent with a small to moderate polarized gluon distribution, so that the anomaly term is not significant in the determination of the constituent contributions to the spin of the proton. We have analyzed the consistency of the results obtained from various sets of data and the Biorken sum rule. Although all data are consistent with the sum rule, the polarized distributions from different experiments vary, even with higher order QCD corrections taken into account. Results split into two models, one set implying a large polarized strange sea which violates the positivity bound, and the other set yielding a smaller polarized strange sea. Only further experiments which extract information about the polarized sea will reconcile these differences. We suggest specific experiments which can be performed to determine the size of the polarized sea and gluons.
Date: January 4, 1996
Creator: Ramsey, G. P. & Goshtasbpour, M.
Partner: UNT Libraries Government Documents Department

Determination of {alpha}{ sub s}} and Measurements of R{sub L}, k and |V{sub cs}| from {nu} - N DIS at CCFR

Description: We present recent QCD results in {nu}-N scattering at the Fermilab CCFR experiment. We present the latest Next-to-Next-to-Leading order strong coupling constant, {alpha}s , extracted from Gross-Llewellyn-Smith sum rule. The value of {alpha}s from this measurement, at the mass of Z boson, is {alpha}{sup NNLO}{sub s} (M{sup 2}{sub Z} ) = 0:114 {sup +0 : 009}{sub -0.012} Measurements of charged current neutrino and anti-neutrino nucleon interactions in the CCFR detector are used to extract the structure functions, F2, xF{sup {nu}}{sub 3} , xF{sup {anti{nu}}}{sub 3} and R(longitudinal) in the kinematic region 0:01 < x < 0:6 and 1 < Q 2 < 300 GeV{sup 2}. The new measurements of R in the x < 0:1 region provide a constraint on the level of the gluon distribution. The x and Q{sup 2} dependence of R is compared with a QCD based fit to previous data. The CKM matrix element jVcs j is extracted from a combined analysis of xF3 and dimuon data.
Date: October 1, 1998
Creator: al., Jae Yu et
Partner: UNT Libraries Government Documents Department

Superfluidity, Bose condensation and neutron scattering in liquid {sup 4}He

Description: The relation between superfluidity and Bose condensation in {sup 4}He provides lessons that may be valuable in understanding the strongly correlated electron system of high {Tc} superconductivity. Direct observation of a Bose condensate in the superfluid by deep inelastic neutron scattering measurements has been attempted over many years. But the impulse approximation, which relates momentum distributions to neutron scattering structure functions, is broadened by final state effects. Nevertheless, the excellent quantitative agreement between ab initio quantum many body theory and high precision neutron experiments provides confidence in the connection between superfluidity and Bose condensation.
Date: April 1, 1997
Creator: Silver, R.N.
Partner: UNT Libraries Government Documents Department

Measurements of the longitudinal structure function and |V{sub cs}| in the CCFR experiment

Description: Measurements of charged current neutrino and anti-neutrino nucleon interactions in the CCFR detector are used to extract the structure functions, F{sub 2}, xF{sub 3}{sup {nu}} , xF{sub 3}{sup {anti {nu}}} and R(longitudinal) in the kinematic region 0.01 < x < 0.6 and 1 < Q{sup 2} < 300 GeV{sup 2}. The new measurements of R in the x < 0.1 region provide a constraint on the level of the gluon distribution. The x and Q{sup 2} dependence of R is compared with a QCD based fit to previous data. The CKM matrix element {vert_bar}V{sub cs}{vert_bar} is extracted from a combined analysis of xF{sub 3} and dimuon data.
Date: July 1, 1998
Creator: Yang, U.K.
Partner: UNT Libraries Government Documents Department

Calculation of the QED correction to the recoil proton polarization by the electron structure function method

Description: Model independent radiative correction to the recoil proton polarization for the elastic electron-proton scattering is calculated within method of electron structure functions. The explicit expressions for the recoil proton polarization are represented as a contraction of the electron structure and the hard part of the polarization dependent contribution into cross-section. The calculation of the hard part with first order radiative correction is performed. The obtained representation includes the leading radiative corrections in all orders of perturbation theory and the main part of the second order next-to-leading ones. Numerical calculations illustrate our analytical results.
Date: December 1, 2000
Creator: Afanasev, A.V.; Akushevich, I. & Merenkov, N.P.
Partner: UNT Libraries Government Documents Department

Quark-Hadron Duality in Structure Functions

Description: While quark-hadron duality is well-established experimentally, the current theoretical understanding of this important phenomenon is quite limited. To expose the essential features of the dynamics behind duality, we use a simple model in which the hadronic spectrum is dominated by narrow resonances made of valence quarks. We qualitatively reproduce the features of duality as seen in electron scattering data within our model. We show that in order to observe duality, it is essential to use the appropriate scaling variable and scaling function. In addition to its great intrinsic interest in connecting the quark-gluon and hadronic pictures, an understanding of quark-hadron duality could lead to important benefits in extending the applicability of scaling into previously inaccessible regions.
Date: April 1, 2001
Creator: Isgur, Nathan; Jeschonnek, Sabine; Melnitchouk, Wally & Orden, J.W. Van
Partner: UNT Libraries Government Documents Department

PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP CIRCUM-PAN-PACIFIC RIKEN SYMPOSIUM ON HIGH ENERGY SPIN PHYSICS, VOLUME 25

Description: The Circum-Pan-Pacific Riken Symposium on High Energy Spin Physics was held at Oukouchi Memorial Hall in Riken from November 3 through 6, 1999. It was held as a joint meeting of the 2nd Circum-Pan-Pacific Symposium on High Energy Spin Physics and the 3rd of the series of Riken Symposia related to the RHIC-SPIN. The 1st Circum-Pan-Pacific Symposium on High Energy Spin Physics was held at Kobe in 1996 and the RHIC-SPIN Riken Symposia had been held every two years since 1995. As Prof. Ozaki mentioned in his talk at the beginning of this meeting, the RHIC was ready for the first beam, physics experiments scheduled in 2000, and the RHIC-SPIN would start in 2001. It was therefore considered to be very timely for the researchers in the field of high energy spin physics to get together, clarifying the present status of the field and discussing interesting and important topics as well as experimental subjects to be pursued. It is especially important for the success of the RHIC-SPIN project that the researchers in the neighboring countries surrounding the Pacific are actively involved in it. This is why the above two series were joined in this. symposium. The subjects discussed in the symposium include: Hard processes probing spin-structure functions, polarization mechanisms in high energy reactions, lattice studies of polarized structure functions, theoretical models for the nucleon and its spin structure, RHIC and RHIC-SPIN projects, results and future projects of existing experimental facilities. Totally 73 scientists participated in the symposium, 27 from abroad and 46 from Japan. it consisted of 13 main sessions, with 33 invited and contributed talks, and 4 discussion sessions covering recent experimental and theoretical developments and important topics in high energy spin physics and closely related fields.
Date: June 28, 2000
Creator: Kumano, S.; Shibata, T. A. & Yazaki, K.
Partner: UNT Libraries Government Documents Department

GAS CURTAIN EXPERIMENTAL TECHNIQUE AND ANALYSIS METHODOLOGIES

Description: The qualitative and quantitative relationship of numerical simulation to the physical phenomena being modeled is of paramount importance in computational physics. If the phenomena are dominated by irregular (i. e., nonsmooth or disordered) behavior, then pointwise comparisons cannot be made and statistical measures are required. The problem we consider is the gas curtain Richtmyer-Meshkov (RM) instability experiments of Rightley et al. (13), which exhibit complicated, disordered motion. We examine four spectral analysis methods for quantifying the experimental data and computed results: Fourier analysis, structure functions, fractal analysis, and continuous wavelet transforms. We investigate the applicability of these methods for quantifying the details of fluid mixing.
Date: January 1, 2001
Creator: KAMM, J. R. & AL, ET
Partner: UNT Libraries Government Documents Department

Moments of the proton F{sub 2} structure function at low Q{sup 2}

Description: The authors review the status of inclusive electron-proton scattering F{sub 2} structure function data in both the nucleon resonance region and the deep inelastic region, at momentum transfers below 5 (GeV/c){sup 2}. From these data they construct moments of F{sub 2}, down to momentum transfers of Q{sup 2}{approx}0.1(GeV/c){sup 2}. The second moment is only slowly varying with Q{sup 2} down to Q{sup 2}{approx}1, which is a reflection of duality. Below Q{sup 2} of 1 (GeV/c){sup 2}, the Q{sup 2} dependence of the moments is predominantly governed by the elastic contribution, whereas the inelastic channels still seem governed by local duality.
Date: May 1, 2000
Creator: Armstrong, C.S.; Ent, R.; Keppel, C.E.; Liuti, S.; Niculescu, G. & Niculescu, I.
Partner: UNT Libraries Government Documents Department

Recent QCD results in {nu} - N deep-inelastic-scattering at CCFR/NUTEV

Description: We present recent QCD results in {nu}-N scattering at the Fermilab CCFR/NuTeV experiments. We present the latest Next-to-Next-Leading order strong coupling constant, {alpha}{sub s}, extracted from Gross-Llewellyn-Smith sum rule. The value of {alpha}{sub s} from this measurement, at the mass of Z boson, is {alpha}{sub s}{sup NNLO}(M{sub Z}{sup 2})=0.114{sub -0.012}{sup +0.009}. We also present a preliminary result of the CCFR F{sub 2} at large-x. This measurement of F{sub 2} is compared to other experiments and various models that provide nuclear effects. We discuss the previous strange sea quark measurement from the CCFR experiment and the prospects for improvements of the measurement in the NuTeV experiment.
Date: August 1, 1998
Creator: Yu, Jaehoon
Partner: UNT Libraries Government Documents Department

Neutron structure function and A=3 mirror nuclei

Description: The authors demonstrate that the free neutron structure function can be extracted in deep-inelastic scattering from A=3 mirror nuclei, with nuclear effects canceling to within 2% for x {approx_lt} 0.85.
Date: June 1, 2000
Creator: Afnan, I.R.; Bissey, F.; Gomez, J.; Katramatou, A.T.; Melnitchouk, W.; Petratos, G.G. et al.
Partner: UNT Libraries Government Documents Department

Effective neutron targets

Description: Because of the lack of a free neutron target, deuterium targets have been used extensively in studying the neutron structure. The unique spin structure of the {sup 3}He ground state wave function and the recent developments in laser technologies made polarized {sup 3}He targets widely used in many experiments from neutron electromagnetic form factor studies to nucleon spin structure function measurements at all major electron accelerator facilities. In this talk, the current status of the polarized {sup 3}He targets will be reviewed. The author will focus on neutron electromagnetic form factor studies using polarized {sup 3}He targets. The polarized nucleon spin structure function measurements using polarized {sup 3}He targets will also be discussed.
Date: July 1, 1997
Creator: Gao, H.
Partner: UNT Libraries Government Documents Department

Polarized structure functions of the nucleon in the resonance region

Description: Aspects of the spin structure functions of proton and neutrons at low momentum transfer Q{sup 2} and energy transfer, {nu}, i.e. in the region of the nucleon resonances are discussed. Experiments to measure A{sub 1}{sup p}, A{sub 2}{sup p} and A{sub 1}{sup n} structure functions at CEBAF in a Q{sup 2} range from 0.15 to 2.0 GeV{sup 2}, and a W range from threshold to 2.2 GeV are presented.
Date: January 1, 1994
Creator: Burkert, Volker
Partner: UNT Libraries Government Documents Department