Bulletin of the American Physical Society
APS April Meeting 2015
Volume 60, Number 4
Saturday–Tuesday, April 11–14, 2015; Baltimore, Maryland
Session H4: Mini-symposium on Partonic Structure beyond Densities: Orbital Motion, Correlations, Fluctuations I |
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Sponsoring Units: DNP Chair: Peter Schweitzer, University of Connecticut Room: Holiday 3 |
Sunday, April 12, 2015 8:30AM - 9:06AM |
H4.00001: Quark-gluon dynamics: what we don't know Invited Speaker: Feng Yuan We have learnt a lot on the internal structure of nucleon through decades of investigations in high energy experiments, including parton distributions, quark and gluon helicity distributions, and some aspects of the generalized parton distributions and transverse momentum distributions. In this talk, we will summarize what we don't know on the partonic structure of nucleon, focusing on new phenomena, new structure, new dynamics which we can obtain in the planned experiments in the future. [Preview Abstract] |
Sunday, April 12, 2015 9:06AM - 9:18AM |
H4.00002: Studies of Transverse Momentum Dependent Parton Distributions and Bessel Weighting Leonard Gamberg We present a new technique for analysis of transverse momentum dependent parton distribution functions, based on the Bessel weighting formalism. Advantages of employing Bessel weighting are that transverse momentum weighted asymmetries provide a means to disentangle the convolutions in the cross section in a model independent way. The resulting compact expressions immediately connect to work on evolution equations for transverse momentum dependent parton distribution and fragmentation functions. As a test case, we apply the procedure to studies of the double longitudinal spin asymmetry in SIDIS using a dedicated Monte Carlo generator which includes quark intrinsic transverse momentum within the generalized parton model. Using a fully differential cross section for the process, the effect of four momentum conservation is analyzed using various input models for transverse momentum distributions and fragmentation functions. We observe a few percent systematic offset of the Bessel-weighted asymmetry obtained from Monte Carlo extraction compared to input model calculations. Bessel weighting provides a powerful and reliable tool to study the Fourier transform of TMDs with controlled systematics due to experimental acceptances and resolutions with different TMD model inputs. [Preview Abstract] |
Sunday, April 12, 2015 9:18AM - 9:30AM |
H4.00003: Measuring transversity in polarized p+p collisions with di-hadron correlations at $\sqrt{s} = $ 200 and 500 GeV at the STAR experiment Keith Landry The transversity distribution $h_1(x)$ of a transversely polarized proton describes the fraction of partons with polarization parallel to the parent proton, carrying a momentum fraction $x$ of the parent proton. This distribution is fundamental for our understanding of the proton spin structure but still very much unknown for values of $x$ larger than about 0.15. In order to understand transversity better, we study transversely spin-polarized proton collisions at STAR, as polarized p+p collisions at RHIC can access this $x$ region and, with a higher scale and transverse momentum, probe a different kinematic regime than SIDIS. We find sizable spin asymmetries in di-hadron correlations, which can be used to directly probe the transversity distribution of quarks inside protons because they arise from a transversely spin polarized quark fragmenting into two hadrons by the Interference Fragmentation Function. This talk will present precision measurements of di-hadron correlations which from the STAR experiment at RHIC, which are sensitive to transversity. [Preview Abstract] |
Sunday, April 12, 2015 9:30AM - 9:42AM |
H4.00004: Phenomenology of Transverse spin: Nucleon Tensor Charge determination Alexei Prokudin, Zhong-Bo Kang, Feng Yuan, Peng Sun We will discuss the present status of the Phenomenology of Transverse spin. In particular we will illustrate the first extraction of the nucleon tensor charge from current experiments by a combined analysis of the Collins asymmetries in two hadron production in $e^+e^-$ annihilations and single inclusive hadron production in deep inelastic scattering processes. The transverse momentum dependent evolution is taken into account, for the first time, in the global fit of the Collins fragmentation functions and the quark transversity distributions at the approximate next-to-leading logarithmic order. We obtain the nucleon tensor charge contribution from up and down quarks as: $\delta u=+0.30^{+0.12}_{-0.11}$ and $\delta d=-0.20_{-0.13}^{+0.35}$ at 90\% of confidence level for momentum fraction $0.0065 \le x_B \le 0.35$ and $Q^2=$ 10 GeV$^2$. [Preview Abstract] |
Sunday, April 12, 2015 9:42AM - 9:54AM |
H4.00005: New results from the Transversity Experiment (E06-010) at JLab Yuxiang Zhao The Transversity Experiment (E06-010) was performed in Hall A at Jeffeson Lab using a longitudinally polarized 5.9 GeV electron beam and transversely polarized $^3$He target. Two spectrometers were employed to detect the outgoing particles: the BigBite spectrometer was set at $30^{\circ}$ on the beam right to detect scattered electrons with momentum from 0.6 to 2.5 GeV; the left HRS spectrometer was set at $16^{\circ}$ on beam left to detect the produced hadrons ($\pi^{\pm}$, $K^{\pm}$ and proton) with a central momentum of 2.35 GeV. Initial results, including target single spin asymmetries (SSA) and beam-target double spin asymmetries (DSA) in semi-inclusive deep inelastic scattering (SIDIS) process, N$^{\uparrow}$(e, e$' \pi^{\pm}$)X, have been reported. In this talk, I will report our latest results, including SSA measurement in the $^3$He$^{\uparrow}$(e, e$' K^{\pm}$)X process, SSA and DSA measurements in the inclusive hadron productions and inclusive DIS process. [Preview Abstract] |
Sunday, April 12, 2015 9:54AM - 10:06AM |
H4.00006: ABSTRACT WITHDRAWN |
Sunday, April 12, 2015 10:06AM - 10:18AM |
H4.00007: Di-hadron production at Jefferson Laboratory Sergio Anefalos Pereira Semi-inclusive deep inelastic scattering (SIDIS) has been used extensively in recent years as an important testing ground for QCD. Studies so far have concentrated on better determination of parton distribution functions, distinguishing between the quark and antiquark contributions, and understanding the fragmentation of quarks into hadrons. Pair of hadrons (di-hadron) SIDIS provides information on the nucleon structure and hadronization dynamics that complements single-hadron SIDIS. The study of di-hadrons allow us to study higher twist distribution functions and Dihadron Fragmentation Functions (DiFF). Together with the twist-2 PDFs ($f$1~,~$g$1~,~$h$1), the Higher Twist (HT)~$e$~and~\textit{hL}~functions are very interesting because they offer insights into the physics of the largely unexplored quark-gluon correlations which provide direct and unique insights into the dynamics inside hadrons. The CLAS spectrometer, installed in Hall-B at Jefferson Lab, has collected data using the CEBAF 6 GeV longitudinally polarized electron beam on longitudinally polarized solid NH3 targets. Preliminary results on beam-, target- and double-spin asymmetries will be presented. [Preview Abstract] |
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