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Mr
Gevorg Karyan
(A.I. Alikhanyan National Science Laboratory)
23/04/2013, 08:50
Spin Physics
Talk in Parallel Session at DIS2013
The HERMES collaboration has measured charge-separated pion and kaon multiplicities in semi-inclusive deep-inelastic scattering using a 27.6 GeV electron or positron beam scattering off a hydrogen or deuterium target. The results are presented as functions of the Bjorken variable x, the negative squared four-momentum transfer Q2, a hadron fractional energy z and the hadron's transverse...
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Nour Makke
(Universita e INFN (IT))
23/04/2013, 09:10
Spin Physics
Talk in Parallel Session at DIS2013
Fragmentation functions (FFs), which turn partons into non-perturbative hadronic bound states in hard-scattering reactions, represent a key ingredient to address proton spin structure in semi-inclusive deep inelastic scattering and proton-proton collisions. Fragmentation functions can not be determined from perturbative Quantum Chromodynamics and have to be extracted from experimental data in...
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Dr
Charlotte Van Hulse
(University of the Basque Country UPV-EHU)
23/04/2013, 09:30
Spin Physics
Talk in Parallel Session at DIS2013
Multiplicities and azimuthal asymmetries were extracted from e+eโ
annihilation data collected with the Belle detector. These data were taken at the KEKB e+eโ collider at a center-of-mass energy of
sqrt(s) = 10.52 GeV. The multiplicities provide the cleanest access to spin-independent fragmentation functions, which describe the hadronization of quarks into final-state hadrons. The low...
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Harold E Jackson Jr
(Argonne National Laboratory)
23/04/2013, 09:50
Spin Physics
Talk in Parallel Session at DIS2013
In 2008 HERMES published the results of an ``isoscalar'' extraction
in leading logarithmic order (LO) in the strong coupling constant of
quantum chromodynamics of the momentum and helicity density distributions of the strange sea in the nucleon from the charged-kaon production in deep-inelastic scattering (DIS) on the deuteron (Phys. Lett. B666, 446 (2008). The shape of the momentum...
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Isabella Garzia
(INFN)
23/04/2013, 10:10
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Hoyoung Kang
(Seoul National University)
23/04/2013, 14:00
Spin Physics
Talk in Parallel Session at DIS2013
In Hall C at the Thomas Jefferson National Laboratory, the Spin Asymmetries of the Nucleon Experiment (SANE, E07-003) measured the spin asymmetries of the proton, using a polarized electron beam and a polarized ammonia target. By rotation of superconducting magnet about the target, parallel and near-perpendicular double spin asymmetries were measured at beam energies of $4.7$ and $5.9 GeV$....
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Vincent Andrieux
(CEA/IRFU, France)
23/04/2013, 14:20
Spin Physics
Talk in Parallel Session at DIS2013
New results on the double spin asymmetry $A_1$ and the spin-dependent structure function of the proton $g_1^p$ as a function of $x_{Bj}$ and $Q^2$ will be presented. They rely on the DIS data collected in 2011 by the COMPASS Collaboration with a polarised muon beam of 200 GeV and a polarised $NH_3$ target. The high energy of the beam allows $A_1$ measurements down to $x_{Bj}$ = 0.0025 for the...
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Alberto Accardi
(Hampton U. and Jefferson Lab)
23/04/2013, 14:40
Spin Physics
Talk in Parallel Session at DIS2013
The Jefferson Lab Angular Momentum (JAM) collaboration is a
new initiative aimed at the study of the angular-momentum-dependent
structure of the nucleon. First results on the determination of
spin-dependent parton distribution functions from world data on
polarized deep-inelastic scattering will be presented and compared
with previous determinations from other groups. Different aspects...
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Sanghwa Park
(Seoul National University)
23/04/2013, 15:00
Spin Physics
Talk in Parallel Session at DIS2013
Measuring the flavor-separated quarks polarization is one of the primary goals in the PHENIX experiment at RHIC in order to understand the proton spin structure. The sea quark parton distriubution fuction (PDF) is not well known while the valence quark PDF is well constrained. The asymmetry of W production $A_{L}$ from polarized proton is sensitive to the helicity distribution of quarks and...
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Prof.
Bernd Surrow
(Temple University)
23/04/2013, 15:20
Spin Physics
Talk in Parallel Session at DIS2013
The STAR experiment at the Relativistic Heavy-Ion Collider at Brookhaven National
Laboratory is carrying out a spin physics program in high-energy polarized proton collisions
at $\sqrt{s}=200\,$GeV and $\sqrt{s}=500\,$GeV
to gain a deeper insight into the spin structure and
dynamics of the proton.
The collision of polarized protons at $\sqrt{s}=500\,$GeV opens a new era of spin-flavor...
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Mr
Emanuele Roberto Nocera
(Universitร degli Studi di Milano & INFN Milano,Italy)
23/04/2013, 15:40
Spin Physics
Talk in Parallel Session at DIS2013
We discuss how a Monte Carlo set of polarized parton distributions, based on inclusive DIS data only, can be supplemented with the experimental information coming from other processes via Bayesian reweighting.
We briefly summarize the features of the reweighting technique and we use it to test the impact of open charm muoproduction and $W^\pm$ production data on a neural network, DIS-based,...
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Mickey Chiu
(Brookhaven National Lab)
23/04/2013, 16:30
Spin Physics
Talk in Parallel Session at DIS2013
Determining the contribution of gluon spin to the proton's total spin is one of the crucial ingredients in resolving the proton spin puzzle. Hints from recent measurements of double longitudinal asymmetries ($A_{LL}$) from the Relativistic Heavy Ion Collider (RHIC) suggest $\Delta g$ is non-zero at moderate values of Bjorken $x \sim 10^{-2}$. In the PHENIX experiment at RHIC, we have a...
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Carl Gagliardi
(Texas A&M University)
23/04/2013, 16:50
Spin Physics
Talk in Parallel Session at DIS2013
One of the primary goals of the RHIC spin program is to determine the gluon polarization distribution within the proton. At leading order, pp collisions involve a mixture of quark-quark, quark-gluon, and gluon-gluon scattering. In RHIC kinematics, the quark-gluon and gluon-gluon contributions dominate, which makes RHIC an ideal tool to explore gluon polarization. The STAR experiment has...
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Dr
Luis Silva
(LIP Lisbon)
23/04/2013, 17:10
Spin Physics
Talk in Parallel Session at DIS2013
In the context of the nucleon spin structure, the contribution from the gluons plays an important role. The so-called gluon polarisation can be determined in DIS through the Photon-Gluon Fusion (PGF) process. In the COMPASS experiment, data were collected with a naturally polarised 160 GeV/c muon beam, impinging on a polarised nucleon. Two analyses aiming at the extraction of the gluon...
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Mr
Grant Webb
(STAR Collaboration)
23/04/2013, 17:30
Spin Physics
Talk in Parallel Session at DIS2013
The STAR Spin program aims to measure the gluon helicity distribution $\Delta g(x)$ in the proton, which remains highly unconstrained at small momentum fractions $x < 0.05$. Dijet reconstruction in polarized proton collisions at $\sqrt s = 500$ GeV will extend these constraints by sampling lower $x$ gluons while also providing more precise information about the partonic kinematics. This...
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Dr
Murad Sarsour
(Georgia State University)
23/04/2013, 17:50
Spin Physics
Talk in Parallel Session at DIS2013
A major emphasis of the RHIC spin program at BNL is to understand the gluon spin contribution, Delta G, to the spin of the proton. The PHENIX experiment at RHIC probes Delta G, utilizing its highly segmented calorimeter, by measuring the double longitudinal spin asymmetry , A_LL, in the production of inclusive channels like pi0 and eta. pi0 data from runs 2005 and 2006 were included in a...
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Dr
Stephen Gliske
(Argonne National lab, for the STAR Collaboration)
23/04/2013, 18:10
Spin Physics
Talk in Parallel Session at DIS2013
The STAR endcap electromagnetic calorimeter (EEMC) was designed to allow measurement of cross sections and spin observables in the forward direction, $1 < \eta < 2$ and with the full azimuth. Using the EEMC to measure double longitudinal spin asymmetries in photonic channels---such as inclusive neutral pions, prompt photon, and prompt photon + jet---allows access to $\Delta G$ covering a lower...
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Sergey Yaschenko
(DESY)
24/04/2013, 08:30
Spin Physics
Talk in Parallel Session at DIS2013
Hard exclusive leptoproduction of real photons, Deeply Virtual Compton Scattering (DVCS), is one of the theoretically cleanest processes to access Generalized Parton Distributions (GPDs). The theoretical framework of GPDs includes information on the correlated transverse spatial and longitudinal momentum distributions of partons in the nucleon. In addition, GPDs may provide a way to...
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Marat Siddikov
(Universidad Santa Maria)
24/04/2013, 08:50
Spin Physics
Talk in Parallel Session at DIS2013
The analysis of deeply virtual meson production is extended to neutrino-production of the pseudo-Goldstone mesons (pions, kaons, eta-mesons) on nucleons, with the flavor content of the recoil baryon either remaining intact, or changing to a hyperon from the SU(3) octet. We rely on the SU(3) relations and express all the cross-sections in terms of the proton generalized parton distributions...
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Jakub Wagner
(Institute for Nuclear Studies)
24/04/2013, 09:10
Spin Physics
Talk in Parallel Session at DIS2013
We study timelike and spacelike virtual Compton scattering in the generalized Bjorken scaling regime at next to leading order in the strong coupling constant, in the medium energy range which will be studied intensely at JLab12 and in the COMPASS-II experiment at CERN. We show that the Born amplitudes get sizeable O(\alpha_s) corrections and, even at moderate energies, the gluonic...
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Dr
Samuel Wallon
(LPT Orsay and UPMC University)
24/04/2013, 09:30
Spin Physics
Talk in Parallel Session at DIS2013
We derive an all order resummation formula for the deeply virtual Compton scattering amplitude, which takes into account soft-collinear gluon exchanges in the partonic (quark gluon) amplitude. We identify at each order of the perturbative series the diagrams responsible in a specific gauge to the leading contributions. An exponentiated expression results in a simple closed expression valid in...
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Bohdan Marianski
(NCBJ)
24/04/2013, 09:50
Spin Physics
Talk in Parallel Session at DIS2013
Spin density matrix elements (SDMEs) have been determined for exclusive
$\omega$ meson production on hydrogen and deuterium targets, in the HERMES
kinematic region of $1.0 < Q^{2} < 10.0$ GeV$^2$ and $3.0 < W < 6.3$ GeV and
$-t'< 0.2 $ GeV$^{2}$. The data, from which SDMEs are determined, were accumulated
with the HERMES forward spectrometer during the running period of 1996- 2007 using...
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Katharina Schmidt
(Albert-Ludwigs-Universitaet Freiburg (DE))
24/04/2013, 10:10
Spin Physics
Talk in Parallel Session at DIS2013
Generalized parton distributions (GPDs) provide a dynamical picture of the nucleon. The exclusive production of $\rho^0$ mesons off a transversely polarised target is sensitive to the nucleon helicity-flip GPDs $E$ which are related to the total angular momentum of quarks and gluons.\\
In 2007 and 2010 the COMPASS experiment at CERN collected data by scattering a 160 GeV/c muon beam on a...
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Markus Diehl
(DESY)
24/04/2013, 11:00
Spin Physics
Talk in Parallel Session at DIS2013
I report on a recent fit of generalized parton distributions to the world data of electromagnetic nucleon form factors.
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Dr
Alexei Prokudin
(JLab)
24/04/2013, 11:20
Spin Physics
Talk in Parallel Session at DIS2013
We examine the QCD evolution of the helicity and transversity parton distribution functions when including also their dependence on transverse momentum. Using an appropriate definition of these polarized transverse momentum distributions (TMDs), we describe their dependence on the factorization scale and rapidity cutoff, which is essential for phenomenological applications.
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Mr
Maarten Buffing
(VU University Amsterdam / Nikhef)
24/04/2013, 11:40
Spin Physics
Talk in Parallel Session at DIS2013
We introduce transverse momentum dependent parton distribution functions (TMDs) for quarks and gluons with definite rank. The rank refers to the azimuthal dependence corresponding to the tensorial structure in transverse momenta multiplying universal functions only depending on x and pT^2. In this way only a finite number of functions of definite rank remains for a target with the number...
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Ignazio Scimemi
(Universidad Complutense de Madrid (UCM))
24/04/2013, 12:00
Spin Physics
Talk in Parallel Session at DIS2013
As a product of the factorization theorem of DY processes one can derive the evolution of TMDPDF at NNLL. An implementation of the evolutor is found which overcomes some difficulties due to the presence of the Landau pole. Final results are compared with phenomenology. Future developments are also discussed.
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Isabella Garzia
(INFN)
24/04/2013, 14:00
Spin Physics
Talk in Parallel Session at DIS2013
We present a measurement of the azimuthal asymmetries
induced by the Collins effect in inclusive production of
charged pion pairs, in the e+e- -> pi pi X annihilation process,
where the two pions are produced in opposite hemispheres.
The data collected by the BABAR detector allows the determination
of the Collins fragmentation function as a function of
hadron fractional energies and...
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Dr
Mher Aghasyan
(LNF, INFN)
24/04/2013, 14:20
Spin Physics
Talk in Parallel Session at DIS2013
Studies of single and double-spin asymmetries in pion electro-production in semi-inclusive deep-inelastic scattering of 5.8 GeV polarized electrons from unpolarized and longitudinally polarized targets at the Thomas Jefferson National Accelerator Facility using CLAS will be discussed. The dependence of these amplitudes on Bjorken x and on the pion transverse momentum has been extracted and is...
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Anna Martin
(Universita e INFN (IT))
24/04/2013, 14:40
Spin Physics
Talk in Parallel Session at DIS2013
COMPASS, a fixed target experiment at the CERN SPS, is measuring the partonic structure of the nucleon since 2002. An important part of this program are the measurements of transverse spin effects in semi-inclusive deep inelastic scattering of high energy muons off transversely polarized deuteron and proton solid state targets. This talk is dedicated to the measurements of the Collins and...
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Dr
Bakur Parsamyan
(University of Turin and INFN Turin (IT))
24/04/2013, 15:00
Spin Physics
Talk in Parallel Session at DIS2013
One of the important objectives of the COMPASS experiment (CERN, Geneva) is the exploration of the transverse spin structure of the nucleon via spin dependent azimuthal asymmetries in single-hadron production in deep inelastic scattering of polarized leptons off transversely polarized target. For this purpose a series of measurements were made in COMPASS, using 160 GeV/c longitudinally...
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Christopher Braun
(Friedrich-Alexander-Univ. Erlangen (DE))
24/04/2013, 15:20
Spin Physics
Talk in Parallel Session at DIS2013
The parton distribution function h1 of a transversely polarized quark inside a transversely polarized nucleon, is chiral-odd and therefore not accessible in deep inelastic scattering. It can only be observed in semi-inclusive deep inelastic scattering (SIDIS) in combination with another chiral-odd function like e.g. the two-hadron interference fragmentation function (IFF) H1. The 160 GeV/c...
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Dr
Stephen Gliske
(Argonne National Lab)
24/04/2013, 15:40
Spin Physics
Talk in Parallel Session at DIS2013
Transverse Momentum Dependent (TMD) dihadron production, including vector meson production, allows access to various TMD distribution and fragmentation functions. Dihadron production is complementary to single hadron semi-inclusive DIS measurements, pairing the same distribution functions with different fragmentation functions. While dihadrons present unique measurement opportunities, the...
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Stefano Melis
(University of Torino and INFN)
24/04/2013, 16:30
Spin Physics
Talk in Parallel Session at DIS2013
We present a global re-analysis of the experimental data on azimuthal asymmetries in semi-inclusive deep inelastic scattering (SIDIS), from the HERMES and COMPASS Collaborations, and in e^+ e^- to h1 h2 X processes, from the Belle Collaboration. Transversity and Collins functions are extracted simultaneously, in the framework of a new and revised global analysis in which a new parameterization...
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Aurore Courtoy
(IFPA)
24/04/2013, 16:50
Spin Physics
Talk in Parallel Session at DIS2013
We propose an extraction of the valence transversity parton distributions. Based on an analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets, this extraction of transversity is performed in the framework of collinear factorization, where dihadron fragmentation functions are involved. The recently released data for proton and deuteron targets at HERMES...
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Zhun Lu
(S)
24/04/2013, 17:10
Spin Physics
Talk in Parallel Session at DIS2013
We study the beam spin asymmetry $A_{LU}^{\sin\phi_h}$ in semi-inclusive $\pi^0$ electroproduction contributed by the T-odd twist-3 distribution function $g^\perp(x,k_T^2)$.
We calculate this transverse momentum dependent distribution function for the $u$ and $d$ quarks inside the proton in a spectator model including the scalar and the axial-vector diquark components.
Using the model...
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Bakur Parsamyan
(Universita e INFN (IT))
25/04/2013, 08:30
Spin Physics
Talk in Parallel Session at DIS2013
The study of the spin structure of the nucleon and of the effects
due to the quarks transverse momentum are part of the scientific program of COMPASS, a fixed target experiment at the CERN SPS.
The azimuthal modulations which appear in the cross-section of SIDIS off unpolarised targets give insight on the intrinsic momentum structure of the nucleon and on the possible correlation between...
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Prof.
Jacques SOFFER
(Temple University, Philadelphia, PA USA)
25/04/2013, 08:50
Spin Physics
Talk in Parallel Session at DIS2013
The transverse single-spin asymmetry of neutrons produced at forward
rapidities in polarized pp collisions is calculated by means of an interesting interference mechanism and compared with a large effect
observed from recent measurements by the PHENIX experiment at RHIC.
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Dr
Stefano Melis
(University of Torino and INFN)
25/04/2013, 09:10
Spin Physics
Talk in Parallel Session at DIS2013
Single spin asymmetries, AN, for inclusive particle production in pp collisions are considered within a generalized parton model with inclusion of spin and tranverse momentum effects.
We consider the potential role of the Sivers effect in AN, as extracted from a careful analysis of azimuthal asymmetries in SIDIS, and discuss its phenomenological consequences in connection with a recently...
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Steven Heppelmann
(Penn State University for the STAR Collaboration)
25/04/2013, 09:30
Spin Physics
Talk in Parallel Session at DIS2013
The STAR collaboration has collected two large data sets for measurement of forward ฯ^0 transverse single spin asymmetries (SSA) in polarized pp collisions. Preliminary results and analysis progress will be presented for data from two RHIC runs, from RHIC Run 11 (2011) with energy โs=500 GeV and with luminosity of 22 pb-1 and from RHIC Run 12 (2012) with โs=200 GeV and with luminosity of 18...
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Oleg Eyser
(B)
25/04/2013, 09:50
Spin Physics
Talk in Parallel Session at DIS2013
Understanding the spin structure of the proton is deeply entangled with the properties and dynamics of quarks and gluons as descibed by the theory of quantum chromodynamics (QCD). Transversity is one of three leading twist parton distribution functions in collinear perturbative QCD and so far the least well known due to its chiral odd nature. Experimentally, it can only be observed in...
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Dr
Wilco den Dunnen
(University of Tรผbingen), Dr
Wilco den Dunnen
(VU University Amsterdam)
25/04/2013, 11:00
Spin Physics
Talk in Parallel Session at DIS2013
We present the di-photon distribution in the decay of an arbitrary spin-0 and spin-2 boson produced from gluon fusion, taking into account the fact that the gluons inside an unpolarized proton are linearly polarized to some extent. The gluon polarization brings about a difference in the transverse momentum distribution of positive and negative parity states. At the same time, it causes the...
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Kazuhiro Tanaka
25/04/2013, 11:20
Spin Physics
Talk in Parallel Session at DIS2013
We discuss the gluonic correlations in the transversely polarized nucleon, which are relevant to single and double spin asymmetries in various hard processes. We explain that the single transverse-spin asymmetry (SSA) to be observed in the D-meson production with large
transverse-momentum in semi-inclusive deep inelastic scattering, $e p^\uparrow \rightarrow e D X$, is induced by the...
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Fabio Dominguez
(IPhT Saclay)
25/04/2013, 11:40
Spin Physics
Talk in Parallel Session at DIS2013
We show explicitly how the linearly polarized gluon distributions appear naturally in high-energy dense-dilute collisions, where the small-x effects are important, and that under the proper kinematic conditions our results agree with the TMD-factorization formalism. In particular, the processes of dijet production in DIS and Drell-Yan in p-A collisions are studied and it is shown that they...
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Koichi Kanazawa
(Niigata University)
25/04/2013, 12:00
Spin Physics
Talk in Parallel Session at DIS2013
We study the contribution of the twist-3 fragmentation function
to the single transverse-spin asymmetry in SIDIS within the framework of
the collinear factorization. Using the Ward-Takahashi identities in QCD,
we establish the collinear twist-3 formalism in the Feynman gauge to
calculate this contribution with manifest color gauge invariance. Then
we present a complete...
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