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Parton Distributions and Spin-Orbital Correlations

Description: In this talk, I summarize a recent study showing that the large-x parton distributions contain important information on the quark orbital angular momentum of nucleon. This contribution could explain the conflict between the experimental data and the theory predictions for the polarized quark distributions. Future experiments at JLab shall provide further test for our predictions.
Date: September 24, 2007
Creator: Yuan, Feng
Partner: UNT Libraries Government Documents Department

Global polarization measurement in Au+Au collisions

Description: The system created in non-central relativisticnucleus-nucleus collisions possesses large orbital angular momentum. Dueto spin-orbit coupling, particles produced in such a system could becomeglobally polarized along the direction of the system angular momentum. Wepresent the results of Lambda and anti-Lambda hyperon global polarizationmeasurements in Au+Au collisions at sqrt sNN=62.4 GeV and 200 GeVperformed with the STAR detector at RHIC. The observed globalpolarization of Lambda and anti-Lambda hyperons in the STAR acceptance isconsistent with zero within the precision of the measurements. Theobtained upper limit, lbar P Lambda, anti-Lambda rbar<= 0.02, iscompared to the theoretical values discussed recently in theliterature.
Date: August 2, 2007
Creator: Abelev, B.I.; Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett,J.; Anderson, B.D. et al.
Partner: UNT Libraries Government Documents Department

Excited charmed mesons

Description: The experimental status of excited charmed mesons is reviewed and is compared to theoretical expectations. Six states have been observed and their properties are consistent with those predicted for excited charmed states with orbital angular momentum equal to one.
Date: May 1, 1995
Creator: Butler, J.N. & Shukla, S.
Partner: UNT Libraries Government Documents Department

PARTON DISTRIBUTIONS AND SPIN-ORBITAL CORRELATIONS.

Description: In this talk, the author summarizes a recent study showing that the large-x parton distributions contain important information on the quark orbital angular momentum of nucleon. This contribution could explain the conflict between the experimental data and the theory predictions for the polarized quark distributions. Future experiments at JLAB shall provide further test for our predictions.
Date: May 21, 2007
Creator: FENG,Y.
Partner: UNT Libraries Government Documents Department

SUGGEL: A Program Suggesting the Orbital Angular Momentum of a Neutron Resonance from the Magnitude of its Neutron Width

Description: The SUGGEL computer code has been developed to suggest a value for the orbital angular momentum of a neutron resonance that is consistent with the magnitude of its neutron width. The suggestion is based on the probability that a resonance having a certain value of g{Gamma}{sub n} is an l-wave resonance. The probability is calculated by using Bayes' theorem on the conditional probability. The probability density functions (pdf's) of g{Gamma}{sub n} for up to d-wave (l=2) have been derived from the {chi}{sup 2} distribution of Porter and Thomas. The pdf's take two possible channel spins into account. This code is a tool which evaluators will use to construct resonance parameters and help to assign resonance spin. The use of this tool is expected to reduce time and effort in the evaluation procedure, since the number of repeated runs of the fitting code (e.g., SAMMY) may be reduced.
Date: February 2, 2001
Creator: Oh, S.Y.
Partner: UNT Libraries Government Documents Department

Global quark polarization in non-central A+A collisions

Description: Partons produced in the early stage of non-central heavy-ioncollisionscan develop a longitudinal fluid shear because of unequal localnumber densities of participant target and projectile nucleons. Undersuch fluid shear, local parton pairs with non-vanishing impact parameterhave finite local relative orbital angular momentum along the directionopposite to the reaction plane. Such finite relative orbitalangularmomentum among locally interacting quark pairs can lead to global quarkpolarization along the same direction due to spin-orbital coupling. Locallongitudinal fluid shear is estimated within both Landau fireball andBjorken scaling model of initial parton production. Quark polarizationthrough quark-quark scatterings with the exchange of a thermal gluon iscalculated beyond small-angle scattering approximation in a quark-gluonplasma. The polarization is shown to have a non-monotonic dependence onthe local relative orbital angular momentum dictated by the interplaybetween electric and magnetic interaction. It peaks at a value ofrelative orbital angular momentum which scales with the magnetic mass ofthe exchanged gluons. With the estimated small longitudinal fluid shearin semi-peripheral Au+Au collisions at the RHIC energy, the final quarkpolarization is found to be small left hbar P_q right hbar<0.04 inthe weak coupling limit. Possible behavior of the quark polarization inthe strong coupling limit and implications on the experimental detectionof such global quark polarization at RHIC and LHC are alsodiscussed.
Date: October 12, 2007
Creator: Gao, Jian-Hua; Chen, Shou-Wan; Deng, Wei-tian; Tang, Zuo-Tang; Wang, Qun & Wang, Xin-Nian
Partner: UNT Libraries Government Documents Department

The transverse momentum dependent distribution functions in the bag model

Description: Leading and subleading twist transverse momentum dependent parton distribution functions (TMDs) are studied in a quark model framework provided by the bag model. A complete set of relations among different TMDs is derived, and the question is discussed how model-(in)dependent such relations are. A connection of the pretzelosity distribution and quark orbital angular momentum is derived. Numerical results are presented, and applications for phenomenology discussed. In particular, it is shown that in the valence-x region the bag model supports a Gaussian Ansatz for the transverse momentum dependence of TMDs.
Date: January 29, 2010
Creator: Avakian, Harut; Efremov, Anatoly; Schweitzer, Peter & Yuan, Feng
Partner: UNT Libraries Government Documents Department

Orbitally Excited Baryon Spectroscopy in the 1/Nc Expansion

Description: The discussion of the 70-plet of negative parity baryons illustrates the large N{sub c} QCD approach to orbitally excited baryons. In the case of the l = 1 baryons the existing data allows to make numerous predictions to first order in the SU(3) symmetry breaking. New relations between splittings are found that follow from the spin-flavor symmetry breaking. The Lambda(1405) is well described as a three-quark state and a spin-orbit partner of the Lambda(1520). Singlet states with higher orbital angular momentum l are discussed.
Date: April 1, 2002
Creator: Schat, C.L.
Partner: UNT Libraries Government Documents Department

Phases of resonant amplitudes: {pi}N {Yields} {pi}{delta}

Description: The phases of resonant amplitudes in pi N yields pi DELTA are studied in a modified version of SU(6)w in which amplitudes involving different relative orbital angular momenta l are uncoupled from one another. This form of SU(6)/sub W/ is equivalent to one studied recently by Melosh, in which the set of selection rules for decays is extended to allow for more types of transition than in the original version of this symmetry. The predictions are compared with a recent preliminary analysis by Herndon et al. Even the extended (''l-broken'') version of SU(6)/sub W/ is found to disagree with the present experimental solution. If this solution persists, it constitutes the strongest present evidence against such a symmetry. (auth)
Date: May 23, 1973
Creator: Faiman, D. & Rosner, J.
Partner: UNT Libraries Government Documents Department

Gauge/Gravity Duality and Hadron Physics in the Light-Front

Description: We discuss some remarkable features of the light-front holographic mapping of classical gravity in anti-de Sitter space modified by a confining dilaton background. In particular, we show that a positive-sign dilaton solution exp(+k{sup 2}z{sup 2}) has better chances to describe the correct hadronic phenomenology than the negative solution exp (-k{sup 2}z{sup 2}) extensively studied in the literature. We also show that the use of twist-scaling dimensions, instead of canonical dimensions, is required to give a good description of the spectrum and form factors of hadrons. Another key element is the explicit connection of AdS modes of total angular momentum J with the internal structure of hadrons and the proper identification of the orbital angular momentum of the constituents.
Date: August 25, 2010
Creator: de Teramond, Guy F.; U., /Costa Rica; Brodsky, Stanley J. & /SLAC /Southern Denmark U., CP3-Origins
Partner: UNT Libraries Government Documents Department

Observation of the Upsilon(13DJ ) Bottomonium State through Decays to pi+pi-Upsilon(1S)

Description: Based on 122X10{sup 6} {upsilon}(3S) events collected with the BABAR detector, we have observed the {upsilon}(1{sup 3}D{sub J}) bottomonium state through the {upsilon}(3S){yields}{gamma}{gamma}{upsilon}(1{sup 3}D{sub J}){yields}{gamma}{gamma}{pi}{sub +}{pi}{sub -}{upsilon}(1S) decay chain. The significance is 6.2 standard deviations including systematic uncertainties. The mass of the J = 2 member of the {upsilon}(1{sup 3}D{sub J}) triplet is determined to be 10164.5{-+}0.8 (stat.) {-+} 0.5 (syst.) MeV/c{sup 2}. We use the {pi}{sup +}{pi}{sup -} invariant mass and decay angular distributions to confirm the consistency of the observed state with the orbital angular momentum and parity assignments of the {upsilon}(1{sup 3}D{sub J}).
Date: June 2, 2010
Creator: del Amo Sanchez, P.; Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; /Annecy, LAPP et al.
Partner: UNT Libraries Government Documents Department

Charm Spectroscopy from B Factories

Description: A brief review of the excited D{sub s} and D mesons is presented. A precision measurement of the D{sub s1}(2536) mass and width parameters is reported by BABAR. Finally, a recent BABAR study of the D{pi} and D*{pi} final states shows first observations of the radial excitations of the D{sup 0}, D*{sup 0}, and D*{sup +}, as well as the L = 2 excited states of the D{sup 0} and D{sup +}, where L is the orbital angular momentum of the quarks.
Date: February 7, 2011
Creator: Benitez, J.
Partner: UNT Libraries Government Documents Department

Statistics of physical properties of dark matter clusters

Description: We have identified over 2000 well resolved cluster halos, and also their associated bound subhalos, from the output of 1024{sup 3} particle cosmological N-body simulation (of box size 320h{sup -1}Mpc and softening length 3.2h{sup -1}kpc). We present an algorithm to identify those halos still in the process of relaxing into dynamical equilibrium, and a detailed analysis of the integral and internal physical properties for all the halos in our sample. The majority are prolate, and tend to rotate around their minor principle axis. We find there to be no correlation between the spin and virial mass of the clusters halos and that the higher mass halos are less dynamically relaxed and have a lower concentration. Additionally, the orbital angular momentum of the substructure is typically well aligned with the rotational angular momentum of the ''host'' halo. There is also evidence of the transfer of angular momentum from subhalos to their host. Overall, we find that measured halo properties are often significantly influenced by the fraction of mass contained within substructure. Dimensionless properties do depend weakly on the ratio of halo mass (M{sub h}) to our characteristic mass scale (M{sub *} = 8 x 10{sup 14}h{sup -1}M{sub {circle_dot}}). This lack of self-similarity is in the expected sense in that, for example, ''old halos'' with M{sub h}/M{sub *} &lt;&lt; 1 have less substructure than ''young halos'' with M{sub h}/M{sub *} &gt;&gt; 1.
Date: September 1, 2005
Creator: Shaw, Laurie; Weller, Jochen; Ostriker, Jeremiah P. & Bode, Paul
Partner: UNT Libraries Government Documents Department

Case A Binary Evolution

Description: We undertake a comparison of observed Algol-type binaries with a library of computed Case A binary evolution tracks. The library consists of 5500 binary tracks with various values of initial primary mass M{sub 10}, mass ratio q{sub 0}, and period P{sub 0}, designed to sample the phase-space of Case A binaries in the range -0.10 {le} log M{sub 10} {le} 1.7. Each binary is evolved using a standard code with the assumption that both total mass and orbital angular momentum are conserved. This code follows the evolution of both stars until the point where contact or reverse mass transfer occurs. The resulting binary tracks show a rich variety of behavior which we sort into several subclasses of Case A and Case B. We present the results of this classification, the final mass ratio and the fraction of time spent in Roche Lobe overflow for each binary system. The conservative assumption under which we created this library is expected to hold for a broad range of binaries, where both components have spectra in the range G0 to B1 and luminosity class III - V. We gather a list of relatively well-determined observed hot Algol-type binaries meeting this criterion, as well as a list of cooler Algol-type binaries where we expect significant dynamo-driven mass loss and angular momentum loss. We fit each observed binary to our library of tracks using a {chi}{sup 2}-minimizing procedure. We find that the hot Algols display overall acceptable {chi}{sup 2}, confirming the conservative assumption, while the cool Algols show much less acceptable {chi}{sup 2} suggesting the need for more free parameters, such as mass and angular momentum loss.
Date: March 28, 2001
Creator: Nelson, C A & Eggleton, P P
Partner: UNT Libraries Government Documents Department

Sivers and Boer-Mulders functions in Light-Cone Quark Models

Description: Results for the naive-time-reversal-odd quark distributions in a light-cone quark model are presented. The final-state interaction effects are generated via single-gluon exchange mechanism. The formalism of light-cone wave functions is used to derive general expressions in terms of overlap of wave-function amplitudes describing the different orbital angular momentum components of the nucleon. In particular, the model predictions show a dominant contribution from S- and P-wave interference in the Sivers function and a significant contribution also from the interference of P and D waves in the Boer-Mulders function. The favourable comparison with existing phenomenological parametrizations motivates further applications to describe azimuthal asymmetries in hadronic reactions.
Date: January 29, 2010
Creator: Pasquini, Barbara & Yuan, Feng
Partner: UNT Libraries Government Documents Department

Globally Polarized Quark-gluon Plasma in Non-central A+ACollisions

Description: Produced partons have large local relative orbital angular momentum along the direction opposite to the reaction plane in the early stage of non-central heavy-ion collisions. Parton scattering is shown to polarize quarks along the same direction due to spin-orbital coupling.Such global quark polarization will lead to many observable consequences,such as left-right asymmetry of hadron spectra, global transverse polarization of thermal photons, dileptons and hadrons. Hadrons from the decay of polarized resonances will have azimuthal asymmetry similar to the elliptic flow. Global hyperon polarization is predicted with indifferent hadronization scenarios and can be easily tested.
Date: October 1, 2004
Creator: Liang, Zuo-tang & Wang, Xin-Nian
Partner: UNT Libraries Government Documents Department

Current quarks, constituent quarks, and symmetries of resonance decays

Description: The transformation between ''current'' quarks and ''constituent'' quarks recently suggested by Melosh is examined with respect to its predictions for pionic decays of resonances. It implies the use of SU(6)/sub W/ for classifying particle states but not for describing decay processes. lnstead, pion emission proceeds via DELTA L/sub z/ = 0, plus or minus 1, where L is the internal (''quark'') orbital angular momentum. This decay symmetry is called SU(6)/sub W/ (DELTA L/sub z/ = 0, plus or minus 1). It is proven equivalent for any decay A yields B + pi (where A, B are arbitrary qq-bar or qqq hadrons) to the /sup 3/P/sub 0/ quark-pair creation model for such decays, as formulated by Micu, Colglazier, Petersen and Rosner. The roles of final orbital angular momenta l and of SU(3) x SU(3) subgroups of SU(6)w are also discussed, and some new predictions are made for decays of meson resonances below 1700 MeV. (auth)
Date: April 18, 1973
Creator: Hey, A.J.G.; Rosner, J.L. & Weyers, J.
Partner: UNT Libraries Government Documents Department

Observation of new resonances decaying to $D\pi$ and $D^*\pi$ in inclusive $e^ e^-$ collisions near $\sqrt{s}

Description: The authors present a study of the D{sup +}{pi}{sup -}, D{sup 0}{pi}{sup +}, and D*{sup +}{pi}{sup -} systems in inclusive e{sup +}e{sup -} {yields} c{bar c} interactions in a search for new excited D meson states. they use a dataset, consisting of {approx} 454 fb{sup -1}, collected at center-of-mass energies near 10.58 GeV by the BABAR detector at the SLAC PEP-II asymmetric-energy collider. They observe, for the first time, candidates for the radial excitations of the D{sup 0}, D*{sup 0}, and D*{sup +}, as well as the L = 2 excited states of the D{sup 0} and D{sup +}, where L is the orbital angular momentum of the quarks.
Date: September 14, 2010
Creator: del Amo Sanchez, P.; Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; /Annecy, LAPP et al.
Partner: UNT Libraries Government Documents Department

AdS/QCD and Its Holographic Light-Front Partonic Representation

Description: Starting from the Hamiltonian equation of motion in QCD we find a single variable light-front equation for QCD which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. This light-front wave equation is equivalent to the equations of motion which describe the propagation of spin-J modes on anti-de Sitter (AdS) space.
Date: November 12, 2008
Creator: de Teramond, Guy F. & Brodsky, Stanley J.
Partner: UNT Libraries Government Documents Department