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John Collins (Penn State University)28/04/2015, 09:00WG6 Spin PhysicsIn using transverse-momentum-dependent (TMD) parton densities and fragmentation functions, important non-perturbative information is at large transverse position $b_T$. This concerns both the TMD functions and their evolution. Fits to high energy data tend to predict too rapid evolution when extrapolated to low energies where larger values of $b_T$ dominate. I summarize a new analysis...Go to contribution page
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Prof. Yuji Koike (Niigata University)28/04/2015, 09:25WG6 Spin PhysicsIn this talk, I will present an overview on the current status of the analyses of the spin asymmetries, in particular, single spin asymmetries, using the framework of the collinear twist-3 (CT3) factorization. In this framework, twist-3 quark-gluon or three-gluon correlation functions in the initial nucleon and the twist-3 fragmentation function for the final hadron play a critical...Go to contribution page
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Daniel Pitonyak (Brookhaven National Lab)28/04/2015, 09:50WG6 Spin PhysicsTransverse single-spin asymmetries (TSSAs), denoted A_N, in single-inclusive hard scattering processes are fundamental observables to test perturbative QCD that have been around for almost 40 years. However, many open issues remain as to the origin of TSSAs. Currently two theoretical formalisms are widely used: collinear twist-3 (CT3) factorization and the Generalized Parton Model (GPM). We...Go to contribution page
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Anselm Vossen (Indiana University)28/04/2015, 10:45WG6 Spin PhysicsFragmentation functions are fundamental objects that describe the process by which partons hadronize to colorless hadrons. Precision measurements of fragmentation functions are necessary for the extraction of most aspects of the nucleon structure from semi-inclusive deep inelastic scattering and p+p collision data. Examples are transverse polarization dependent fragmentation functions that...Go to contribution page
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Isabella Garzia (INFN)28/04/2015, 11:10WG6 Spin PhysicsInclusive hadron production cross sections and angular distributions in e+e- collisions shed light on fundamental questions of hadronization and fragmentation processes. We present measurements of the so-called Collins azimuthal asymmetries in inclusive production of hadron pairs, in the e+e- -> h1 h2 X annihilation process, where the two hadrons (either kaon or pions) are produced in...Go to contribution page
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Isabella Garzia (INFN)28/04/2015, 11:35WG6 Spin PhysicsThere has been increasing interest in understanding the spin phenomena in the nucleon, such as the transverse spin structure (the so-called transversity). The semi-inclusive observables in SIDIS experiments are only connected to the product of quark transversity distribution and the Collins fragmentation function (FF). An independent measurement of the Collins FFs in e+e- annihilation makes...Go to contribution page
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Dr Erin SEDER (CEA Saclay, DSM/IRFU/SPhN)28/04/2015, 12:00WG6 Spin PhysicsThe latest measurements of $K^{\pm}$ multiplicities in semi-inclusive deep-inelastic scattering from the COMPASS experiment at CERN are presented. The data were collected using a $160$ $GeV$ muon beam incident on an isoscalar $^{6}LiD$ target. The large statistics collected cover a wide kinematic range and the results are presented in 3-dimensional bins of $x_{Bjorken}$, $y$, and $z$. These...Go to contribution page
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Wenjuan Mao (Southeast University)28/04/2015, 14:00WG6 Spin PhysicsWe study the single-spin asymmetries with the $\sin\phi_S$ and $\sin(2\phi_h -\phi_S)$ angular dependencies of pion production in semi-inclusive deep inelastic scattering off a transversely polarized proton target. We investigate the role of the distributions $f_T$, $h_T$ and $h_T^\perp$ in the $\sin\phi_S$ asymmetry, as well as the role of the distributions $f_T^\perp$, $h_T$ and $h_T^\perp$...Go to contribution page
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Mr Peter Lowdon (University of Zurich)28/04/2015, 14:25WG6 Spin PhysicsThe decomposition of nucleon spin into spin and orbital angular momentum contributions from partons is revisited in the context of quantum field theory. It is shown that commonly used decompositions rely on classical-type arguments for their justification, and that these arguments may no longer hold in the full quantum theory, in particular with respect to the treatment of boundary terms. The...Go to contribution page
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Dr LINGYUN DAI (Indiana University)28/04/2015, 14:50WG6 Spin PhysicsWe study the Sivers asymmetry in semi-inclusive hadron production in deep inelastic scattering. In particular, we concentrate on the contribution from the photon-gluon fusion channel, where the three-gluon correlation functions play the major role within a twist-3 collinear factorization formalism. We establish the matching between such a formalism and the usual transverse momentum dependent...Go to contribution page
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Harleen Dahiya (Dr. B.R. Ambedkar National Institute of Technology)28/04/2015, 15:15WG6 Spin PhysicsThe axial-vector form factors of the low lying octet baryons ($N$, $\Sigma$, $\Xi$ and $\Lambda$) have been studied for the implications of chiral symmetry breaking and SU(3) symmetry breaking for the singlet ($g^0_{A}$) and non-singlet ($g^3_{A}$ and $g^8_{A}$) axial-vector coupling constants. In addition to studying the total strange singlet and non-singlet contents ($G_s^0(Q^2)$,...Go to contribution page
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Mr giulio sbrizzai (Trieste University and INFN)28/04/2015, 16:15WG6 Spin PhysicsRecent results on the transverse spin azimuthal asymmetries in semi-inclusive DIS reactions extracted by the COMPASS Collaboration from the data collected with a transversely polarised proton target are presented. In particular, the interesting kinematical dependencies shown by the Collins and Sivers asymmetries have been further investigated in a multi-dimensional analysis in x, Q^2, z...Go to contribution page
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Dr Salvatore Fazio (Brookhaven National Laboratory)28/04/2015, 16:40WG1 Structure Functions and Parton DensitiesWe present the status and preliminary results on the analysis of kinematically fully reconstructed weak bosons at the STAR experiment. The transverse single spin asymmetry ($A_{N}$) has been measured in transversely polarized proton-proton collisions at $\sqrt{s} = 500$~GeV, with a recorded integrated luminosity of $25~\text{pb}^{-1}$. The measured observable is sensitive to the...Go to contribution page
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J. Osvaldo Gonzalez H. (University of Turin)28/04/2015, 17:05WG6 Spin PhysicsIn order to describe SIDIS over a wide region of transverse momentum qT , one must confront both the perturbative and non-perturbative regimes. In this sense, when extracting the non-perturbative TMDs from experimental data, one should ensure that there exists a smooth transition between the soft gluon resummation regime and the pQCD predictions, at large qT. We present recent results on the...Go to contribution page
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Aurore Courtoy (IFPA)28/04/2015, 17:30WG6 Spin PhysicsWe present an updated extraction of the valence transversity PDF using the most recent COMPASS data with identified pion pairs. The new analysis was carried out using the replica method for both the chiral-odd DiFF and the transversity PDF. This picture represents the current most realistic estimate of the uncertainties on our knowledge of the valence components of the transversity function...Go to contribution page
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Prof. simonetta liuti (university of virginia)29/04/2015, 08:30WG6 Spin PhysicsWe discuss the canonical (Ji) and kinetic/mechanical (Jaffe and Manohar) definitions of partonic orbital angular momentum (OAM). It was recently shown by Hatta and Burkardt that the two definitions correspond to the second moment in intrinsic k_T of the same generalized transverse momentum distribution (GTMD), while they differ in their gauge link structure. At the same time, as...Go to contribution page
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Philipp Karl Jorg (Albert-Ludwigs-Universitaet Freiburg (DE))29/04/2015, 08:55WG6 Spin PhysicsA major part of the COMPASS-II program will be dedicated to the investigation of generalized parton distributions (GPDs) and transverse momentum dependent parton distributions (TMDs), which aim for the most complete description of the partonic structure of the nucleon. GPDs are experimentally accessible via lepton-induced exclusive reactions, in particular the Deeply Virtual Compton...Go to contribution page
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Carlos Munoz Camacho29/04/2015, 09:20WG6 Spin PhysicsDeeply Virtual Compton Scattering (DVCS) is the easiest reaction that probes the Generalized Parton Distributions (GPDs) of the nucleon. GPDs offer the exciting possibility of mapping the 3-D internal structure of protons and neutrons by providing a transverse image of the constituents as a function of their longitudinal momentum. An extensive experimental program is currently pursued at...Go to contribution page
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Mr Maxime DEFURNE (CEA)29/04/2015, 09:45WG6 Spin PhysicsThe deeply virtual $\pi^0$ production cross section can be decomposed according to the polarization of the virtual photon. \begin{equation} \frac{d\sigma}{dt}=\frac{d\sigma_T}{dt}+\epsilon \frac{d\sigma_L}{dt}+\sqrt{2\epsilon (\epsilon+1)}\frac{d\sigma_{TL}}{dt} \cos(\phi)+\epsilon \frac{d\sigma_{TT}}{dt} \cos(2\phi) \end{equation} where $\epsilon$ represents the degree of polarization of...Go to contribution page
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Kazuhiro Tanaka29/04/2015, 10:45WG6 Spin PhysicsThe measurement of exclusive mesoproduction of lepton pair, $\pi^- p \to \ell^+ \ell^- n$, may be performed using the high-intensity pion beams at J-PARC in the near future. The leading hard exclusive amplitude for this process was obtained by E.R. Berger, M. Diehl, and B. Pire [Phys. Lett. B 523 (2001) 265] in terms of the partonic subprocess convoluted with the relevant nonperturbative...Go to contribution page
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Pawel Sznajder (National Centre for Nuclear Research (PL))29/04/2015, 11:10WG6 Spin PhysicsHard exclusive leptoproduction of mesons on nucleons has played an important role in studies of the hadron structure and recently gained a renewed interest as it allows an access to generalised parton distributions (GPDs). The GPDs provide a novel and comprehensive description of the nucleon partonic structure and contain a wealth of new information. In particular, the GPDs give a description...Go to contribution page
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Andreas Metz (Temple University, Philadelphia)29/04/2015, 11:35WG6 Spin PhysicsIn this talk we will address new theoretical work on twist-3 spin asymmetries for the process l + N -> h + X, for which recent data have been obtained. Specifically, we will address the longitudinal-transverse double-spin asymmetry A_LT, and the transverse single-spin asymmetry A_N for a polarized final state hyperon. Open questions and future prospects will be mentioned as well.Go to contribution page
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Carlos Granados (Uppsala University)29/04/2015, 12:00WG6 Spin PhysicsThe nucleon's peripheral transverse charge and magnetization densities are computed in chiral effective field theory in the light--front formulation. The densities are represented in first--quantized form, as overlap integrals of chiral light--front wave functions describing the transition of the nucleon to soft pion--nucleon intermediate states. The new representation leads to a simple...Go to contribution page
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Hari Guragain (PHENIX Collaboration)29/04/2015, 14:00WG6 Spin PhysicsOne of the major objectives of the RHIC spin program at BNL is the measurement of the gluon helicity contribution, $\Delta G$, to the proton spin via measuring the double longitudinal spin asymmetry ($A_{LL}$) in various channels. In PHENIX (Pioneering High Energy Nuclear Interaction eXperiment) the $A_{LL}$ in $\pi^{0}$, $\eta$, $J/\psi$ etc. are measured in wide...Go to contribution page
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Dr Xuan Li (Temple University)29/04/2015, 14:25WG6 Spin PhysicsInclusive jet- and di-jet productions in polarized p+p collisions at $\sqrt{s} = 200$ GeV and $\sqrt{s} = 500$ GeV provide powerful probes to study gluons inside the proton. Inclusive jet production is sensitive to the integral of the gluon distribution over a broad range of $x$. Di-jet production provides better sensitivity to $x$ dependence of gluons. The Solenoidal Tracker at RHIC (STAR)...Go to contribution page
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DEVIKA S GUNARATHNE (urn:Google)29/04/2015, 14:50WG6 Spin PhysicsDevika Gunarathne for the STAR Collaboration Temple University, Philadelphia, PA, USA Email: devika.gunarathne@temple.edu $W^\pm$ boson production in longitudinally polarized $p+p$ collisions provides unique and clean access to the individual helicity polarizations of $u$ / $d$ quarks and anti-quarks. Due to maximal violation of parity, $W$ bosons couple to left-handed quarks and...Go to contribution page
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Mike Beaumier (urn:Google)29/04/2015, 15:15WG6 Spin PhysicsOver the past ten years, the RHIC spin program has deepened our knowledge of proton spin structure as part of a worldwide effort to solve the proton spin puzzle. While we now precisely understand the contribution of valence quarks to the total proton spin, large uncertainties still dominate the predictions describing the contributions of the sea of anti-up and anti-down quarks. In 2013, PHENIX...Go to contribution page
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Dr Nobuo Sato (Jefferson Lab)29/04/2015, 16:15WG6 Spin PhysicsA new global QCD analysis of spin-dependent PDFs has been performed by the JAM (Jefferson Lab Angular Momentum) Collaboration, including all available data on inclusive spin structure functions from CERN, SLAC, DESY and JLab. In particular, we explore the impact of recent high-precision JLab data at high x and low *Q*^2 on the determination of large-*x* PDFs and the extraction of higher...Go to contribution page
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Nilanga Liyanage (University of Virginia (US))29/04/2015, 16:40WG6 Spin PhysicsJefferson lab is well known for its high quality, high polarization electron beam. Jefferson lab polarized beam, combined with the range of polarized proton, deuteron and 3He targets in experimental halls A, B and C, allows for high precision exploration of spin structures of both proton and neutron in the low to intermediate Q2 region. The impact of Jefferson lab precision spin data is...Go to contribution page
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Tomas Kasemets (DESY)29/04/2015, 17:05WG6 Spin PhysicsWe discuss the impact of double parton scattering at the LHC. In particular we focus on the impact of polarization, arising from the spin correlations between two partons inside an unpolarized proton. We demonstrate that the effects can be large in certain kinematic regions and processes and compare our results to data. We further discuss angular asymmetries and similarities as well as...Go to contribution page
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Cristian Pisano (Vrije Universiteit Amsterdam)29/04/2015, 17:30WG6 Spin PhysicsWe consider Higgs plus jet production as a process that is sensitive to the linear polarization of gluons inside the unpolarized protons of the LHC. The leading order expressions for the transverse momentum distribution of the Higgs plus jet pair are calculated in terms of transverse momentum dependent quark and gluon distributions. Both angular independent and azimuthal angular dependent...Go to contribution page
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Matthias Burkardt (NMSU)30/04/2015, 10:45WG6 Spin PhysicsTransverse single-spin asymmetries are not the only observable where the transverce force on quarks in DIS plays a role. For example, higher-twist effects in polarized inclusive DIS can be related to that force. Furthermore the torque due to that force is relevant when comparing the Jaffe-Manohar with the Ji definition for quark orbital angular momentum. I explain the origin of that force in...Go to contribution page
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Dr Kalyan Allada (Massachusetts Institute of Technology)30/04/2015, 11:10WG6 Spin PhysicsSemi-inclusive deep inelastic scattering (SIDIS) is a powerful tool to explore the 3-d structure of nucleon in momentum space. Through a combination of polarized/unpolarized lepton beam and nucleon target one can study various transverse-momentum dependent parton distribution functions (TMDs) that appear in the SIDIS cross-section. TMDs provide a description of nucleon structure in terms of...Go to contribution page
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Kenneth Barish (UC Riverside)30/04/2015, 11:35WG6 Spin Physics(for the PHENIX Collaboration) Transverse single-spin asymmetries (TSSA) provide valuable information about the spin structure of the nucleon. Here, we report results of TSSA in $\eta$ and single-muon production channels in p+p collision. Non-vanishing TSSA in eta meson production channel has been reported for Run-2008 data (Phys. Rev. D 90, 072008), in the forward rapidity region, which...Go to contribution page
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Dr James L. Drachenberg (Valparaiso University)30/04/2015, 12:00WG6 Spin PhysicsCurrent knowledge of nucleon transverse-polarization structure comes from measurements of transverse single-spin asymmetries (SSAs) from semi-inclusive deep inelastic scattering (SIDIS). These measurements, combined with those of $e^{+}e^{-}$ collisions, have allowed the first extraction of transversity with limited constraints at higher values of Bjorken-$x$. One avenue to enrich...Go to contribution page
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