Krzysztof Kurek
(Soltan Institute for Nuclear Studies)
17/04/2007, 09:20
Spin Physics
Results on the deuteron longitudinal inclusive spin-dependent asymmetryA_1^d
and the spindependentstructure function g_1^d are presented. The data have been
collected by the COMPASS experiment at CERN during the years 2002-2004 using 160
GeV/c polarised muon
beam scattered off a polarised 6LiD target. The obtained values for Gamma_1^d, the
first moment of g_1^d(x), and for the...
Lara De Nardo
(DESY / TRIUMF)
17/04/2007, 09:40
Spin Physics
Precise measurements of the spin structure functions $g_1^^p(x,Q2)$ and
$g_1^n(x,Q2)$ are presented over the kinematic range 0.0041 $\leq x
\leq $ 0.9 and 0.18 GeV$^2$ $\leq Q2 \leq $ 20 GeV$^2$. The data were
collected at the HERMES experiment at DESY, in deep-inelastic scattering
of 27.6 GeV longitudinally polarized positrons off longitudinally
polarized hydrogen and deuterium gas...
Dimitar Stamenov
(INRNE, Sofia)
17/04/2007, 10:00
Spin Physics
The results of a new NLO QCD analysis of the world data on inclusive
polarized DIS are presented. The very precise CLAS proton and
deuteron data, as well as the latest COMPASS data on the asymmetry
$A_1^d$ were included in the analysis, and the impact of these data
on polarized parton densities and higher twist effects has been
studied. It is demonstrated that the low Q^2 CLAS data...
Keith Griffioen
(College of William & Mary)
17/04/2007, 10:20
Spin Physics
The CLAS Collaboration at Jefferson Lab has a sustained and comprehensive program
measuring the spin structure function g_1 for the proton and deuteron at low and
intermediate Q2. Precise data with extensive kinematic coverage allow us to better
constrain the polarized parton distributions and to accurately determine various
moments of g_1 as a function of Q2. Our latest results will be...
Christof HENDLMEIER
(University of Regensburg)
17/04/2007, 11:10
Spin Physics
We consider the photoproduction of two hadrons in polarized lepton-nucleon
collisions in the framework of perturbative QCD. After illustrating how to
obtain the experimentally relevant observables a detailed phenomenological
study of the photoproduction of hadron pairs at high transverse momenta is
presented. We show theoretical predictions for the relevant cross sections
and double-spin...
Patricia Liebing
(RIKEN / BNL)
17/04/2007, 11:30
Spin Physics
HERMES has used a high statistics data sample of charged inclusive hadrons to
measure double spin asymmetries as a function of p_T. From these asymmetries
Delta g/g has been extracted in the region of 1<p_T<2 GeV, corresponding
to x\approx0.2-0.3 The information on the background asymmetry and the
subprocess kinematics has been obtained from a Leading Order Monte Carlo
model and...
Susanne Koblitz
(Institut fuer Kernphysik / Universitaet Mainz)
17/04/2007, 11:50
Spin Physics
One of the main goals of the COMPASS experiment at CERN is the
determination of the gluon polarisation in the nucleon, Delta G/G.
It is determined from spin asymmetries measured in the scattering of
160GeV/c polarised muons on a polarised LiD target.
The gluon is accessed by the selection of photon-gluon fusion
events. A selection of PGF events can be obtained with charmed
mesons in the...
Kensuke Okada
(Riken / BNL)
17/04/2007, 12:10
Spin Physics
To study the proton spin structure, the Relativistic Heavy Ion Collider
(RHIC) at BNL provides a unique opportunity by colliding polarized protons.
The hard subprocesses in proton-proton collisions involve gluons in
leading order, therefore measurements of cross section asymmetries
between aligned and anti aligned proton helicities give us information
about the spin dependent gluon...
Renee Fatemi
(MIT)
17/04/2007, 12:30
Spin Physics
Recent STAR results on jet production in polarized p+p collisions at 200GeV at RHIC
Frank Simon
(MIT)
17/04/2007, 14:00
Spin Physics
Recent STAR results on hadron production in polarized p+p collisions at 200GeV at RHIC
Alexander Korzenev
(Mainz University)
17/04/2007, 14:20
Spin Physics
A first evaluation of the polarized valence quark
distribution\Delta u_v(x)+Delta d_v(x) from the COMPASS
experiment (CERN/SPS) is presented. The data were collected
by COMPASS in the years 2002--2004 using a 160 GeV polarized
muon beam scattered off a large polarized 6LiD target and
cover the range 1< Q2 < 100(GeV/c)2 and $0.006<x<0.7.
The analysis is based on the difference...
Philip Cole
(Idaho State University)
17/04/2007, 14:40
Spin Physics
A comprehensive program with polarized electron and photon probes
with unpolarized and polarized proton and duteron targets is undergoing
at JLab. Results and perspectives will be reported.
Karl Slifer
(University of Virginia)
17/04/2007, 15:00
Spin Physics
We have measured the spin structure of the nucleon in the region
of the resonances (final state mass W <2 GeV) at intermediate
four-momentum transfer Q2 ~ 1.3 (GeV/c)2. Double-spin inclusive
asymmetries for longitudinally polarized 5.75 GeV electrons incident
on longitudinal and transverse solid polarized targets were measured
in Jefferson Lab's Hall C. Frozen ammonia and deuterated...
Boris Ermolaev
(Ioffe Physico-Technical Institute)
17/04/2007, 15:20
Spin Physics
Standard Approach (SA) for description of $g_1$ is based on the
DGLAP evolution equations and the special fits for the initial parton
densities. SA accounts for the total resummation of logs of $Q2$ and
lacks the total resummation of leading $ln(1/x)$. In order to meet the
small -$x$ experimental data, SA includes phenomenological singular
factors in the fits. They mimic the...
Ralf Seidl
(University of Illinois at Urbana-Champaign)
17/04/2007, 16:10
Spin Physics
In order to obtain precise information on helicity and transversity
distributions from semi-inclusive measurements in DIS and proton-proton
collisions a good knowledge of fragmentation functions is necessary.
The Belle experiment at the asymmetric e+e- collider KEKB can provide precise
spin averaged and spin dependent fragmentation functions such as the Collins
function and the...
Markus Diefenthaler
(Physikalisches Institut II, Friedrich-Alexander-Universität)
17/04/2007, 16:30
Spin Physics
In 2005 the HERMES collaboration published first evidence for azimuthal
single-spin asymmetries in semi-inclusive production of charged pions on
a transversely polarised hydrogen target.
The measured asymmetries are caused by both the Collins and the Sivers
mechanisms. Their distinctive Fourier components provide signals to
previously unmeasured quantities: the transversity quark...
Andrea Bressan
(INFN Trieste)
17/04/2007, 16:50
Spin Physics
The CERN COMPASS experiment is on the floor collecting data since 2002; in the years
2002,
2003, and 2004 data were collected using a 160 GeV polarized muon beam and a 6LiD
polarized target. In about 20% of the running time the target polarisation was
oriented transversely with respect to the muon beam direction to measure transverse
spin effects in semi inclusive deep inelastic...
Umberto D'Alesio
(Dipartimento di Fisica, Cagliari University)
17/04/2007, 17:10
Spin Physics
We present a global analysis of azimuthal asymmetries in e^+e^- -> h_1 h_2 X
processes (BELLE data) and in semi-inclusive deep inelasticscattering (HERMES and
COMPASS data). It results in the extraction of the Collins fragmentation function and
of the transversity distribution function for u and d quarks. Theseturn out to have
opposite signs and to be sizably smaller than...
Leonard Gamberg
(Penn State Berks, Dept. of Physics)
17/04/2007, 17:30
Spin Physics
This talk will focus on transverse quark spin effects
in SIDIS. I will discuss the theoretical T-odd input
to the cos 2\phi azimuthal asymmetry as well as new work
on the Collins function and the Boer Mulders function,
the essential TMD inputs to this asymmetry.
We will present new estimates of the cos2\phi asymmetry as
a function of P_T, x, and z. I will also talk a bit about the...
Yury Naryshkin
(Petersburg Nuclear Physics Institute)
18/04/2007, 11:10
Spin Physics
Transverse Lambda and Lambda-bar polarization produced inclusively in quasi-real
photon-nucleon scattering have been studied in the HERMES experiment using a 27.6 GeV
positron beam incident on hydrogen and deuterium gas targets. The average transverse
polarizations were found to be P^{Lambda}_n = 0.078 +- 0.006(stat) +- 0.012(syst)
and P^{bar Lambda}_n = -0.025 +- 0.015(stat) +-0.018...
K. Oleg Eyser
(UC Riverside, DESY)
18/04/2007, 11:30
Spin Physics
With recent experimental measurements of various asymmetries at HERMES[1], Belle[2],
STAR[3], and BRAHMS[4] there has been a growing interest in the understanding of the
transversely polarized proton structure. Theoretical explanations include different
mechanisms, such as effects from the Sivers function, the Collins effect, higher
twist contributions, or combinations of all of the above....
Steven Heppelmann
(Penn State)
18/04/2007, 11:50
Spin Physics
J.H. Lee
(BNL)
18/04/2007, 12:10
Spin Physics
Single transverse spin asymmetries (SSA) in transversely polarised pp reactions at the energy regime where pQCD is applicable are expected to be negligibly small in the lowest-oredr QCD approximation, whereas experimentally large SSAs have been observed at high xF. Recently, new measurements of SSAs have been available from semi-inclusive deep-inelastic scattering and transversely polarised pp...
Philipp Haegler
(TU Muenchen)
18/04/2007, 12:30
Spin Physics
In this talk, we present recent results from lattice QCD on the transverse
spin structure of hadrons. Strong correlations between spin, orbital
angular momentum and coordinate degrees of freedom lead to strongly
distorted densities of quarks in hadrons in particular for transverse
quark polarizations. We discuss possible implications of our results for
the Sivers and Boer-Mulders function...
Hiroyuki Kawamura
(RIKEN)
19/04/2007, 09:00
Spin Physics
We study the double-spin asymmetries in transversly/longitudinally
polarized Drell-Yan processes at transverse momentum Q_T of the produced
lepton pair. We first consider the double transverse-spin asymmetry A_{TT}(Q_T)
in the transversely polarized Drell-Yan process in detail, in particular,
in the small Q_T region, where the bulk of dileptons are produced.
The large logarithms due to...
Prof.
Yuji Koike
(Department of Physics, Niigata University)
19/04/2007, 09:20
Spin Physics
We present a consistent framework for the twist-3 calculation for
the single transverse spin asymmetry (SSA). We prove that the consistent
use of the Ward identity for color gauge invariance is crutial to
obtain the factorization property and the gauge invariance of the
twist-3 single-spin-dependent cross section. This proof had been missed
in the previous literature. As an...
Prof.
Kazuhiro Tanaka
(Dept. of Physics, Juntendo University)
19/04/2007, 09:40
Spin Physics
It is known that a dominant QCD mechanism for the single transverse-spin
asymmetry in hard processes is induced by the twist-3 quark-gluon correlations
inside a hadron, combined with the soft-gluonic poles to produce the
interfering phase for the associated partonic hard scattering. We show that
the coupling of the relevant soft gluon to partonic subprocess can be
systematically...
Cedran Bomhof
(Vrije Universiteit Amsterdam)
19/04/2007, 10:00
Spin Physics
The Sivers effect is a possible source for many single spin
asymmetries. The appearance of the Sivers distribution function
is also a testinground for our understanding of universality.
A well-known example of the peculiar universality property of
this function is the relative sign difference of the Sivers
function in SIDIS and Drell-Yan scattering. This opposite sign
is a direct...
Jan Balewski
(IUCF)
19/04/2007, 10:20
Spin Physics
Alessandro Bacchetta
(DESY)
19/04/2007, 11:10
Spin Physics
The cross section for polarized semi-inclusive deep inelastic scattering is
reviewed, including in particular the dependence on the transverse momentum of
the detected hadron. Out of the 18 structure functions appearing in the cross
section, we will discuss the present knowledge of a few selected examples.
Christian Schill
(Univ. Freiburg)
19/04/2007, 11:30
Spin Physics
An important missing piece in our understanding of the spin structure of the
nucleon is the transversity distribution function Delta_Tq(x). It is only
one of the three leading-twist quark distribution functions q(x), Delta q(x)
and Delta_Tq(x) that so-far remains unmeasured. The function Delta_Tq(x)
describes the distribution of transversely polarized quarks in a transversely
polarized...
Marco Radici
(INFN - Sezione Pavia)
19/04/2007, 11:50
Spin Physics
We consider dihadron fragmentation functions, that describe the
fragmentation of a parton in two (unpolarized) hadrons. Using Jet calculus
techniques, we develop evolution equations when these functions are
explicitly depending upon the invariant mass of the produced hadron pair,
the socalled extended dihadron fragmentation functions. We connect our
results to the integrated dihadron...
Aram Kotzinian
(INFN Torino)
19/04/2007, 12:10
Spin Physics
In semi-inclusive DIS of polarized leptons on a transversely polarized target
eight azimuthal modulations appear in the cross-section. Within QCD parton
model four azimuthal asymmetries can be interpreted at leading order, two of
them being the already measured Collins and Sivers asymmetries. The other two
leading twist asymmetries, related to different transverse momentum dependent
quark...
John Lajoie
(Iowa State University)
19/04/2007, 12:30
Spin Physics
The PHENIX upgrade program adds a set of silicon pixel detectors (the VTX and FVTX),
forward calorimetry (the NCC), and Level-1 trigger detectors (the Muon Trigger
Upgrade) to the baseline detector. These upgrades will enhance the ability of PHENIX
to pursue a rich program of spin physics in polarized proton collisions, in
particular at sqrt(s) = 500 GeV. The VTX and FVTX detectors will...
