Strangeness and Spin in Fundamental Physics

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Strangeness and Spin in Fundamental Physics
Varenna, June 19-29, 2007
Spin lectures
Mauro Anselmino The transverse spin structure of
the nucleon Delia Hasch The transverse spin
structure of the nucleon exp. Elliot Leader
The longitudinal spin structure of the
nucleon Werner Vogelsang QCD spin physics in
hadronic interactions Naohito Saito Spin Physics
at RHIC - experiment Raimondo Bertini
Spin physics with strangeness
Spin seminars
Robert Jaffe Gluon spin basics Harut Avakian
Spin Physics at JLab Mariaelena Boglione The
first way to transversity
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Parton transverse motion, spin-k- correlation,
orbiting?
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Transverse single spin asymmetries in SIDIS,
experimentally observed (D. Hasch)
in collinear configurations there cannot be (at
LO) any PT
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Mauro Anselmino The transverse spin structure of
the nucleon - II
About partonic intrinsic motion and SSA
Estimate of transverse motion of quarks TMDs
spin-intrinsic motion correlations in
distribution and fragmentation functions Sivers
and Collins functions SSA in SIDIS Coupling
Collins function and Transversity What do we
learn from Sivers functions? The full structure
of TMDs in SIDIS
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Partonic intrinsic motion
Plenty of theoretical and experimental evidence
for transverse motion of partons within nucleons
and of hadrons within fragmentation jets
qT distribution of lepton pairs in D-Y processes
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pT distribution of hadrons in SIDIS

Hadron distribution in jets in ee processes
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Parton Model with intrinsic motion
Assume struck parton carries 4-momentum k
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SIDIS in parton model with intrinsic k-
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Elementary Mandelstam variables
The on shell condition for the final quark
implies
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Cahn effect
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assuming
one finds
with
Find best values by fitting data on Fh and PT
dependences
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EMC data, µp and µd, E between 100 and 280 GeV
M.A., M. Boglione, U. DAlesio, A. Kotzinian, F.
Murgia and A. Prokudin, C. Türk
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Large PT data explained by NLO QCD corrections
EMC data
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How does intrinsic motion help with SSA?
One can introduce spin-k- correlation in the
Parton Distribution Functions (PDFs) and in the
parton Fragmentation Functions (FFs)
Only possible (scalar) correlation is
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TMDs Sivers function
Boer-Mulders function
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Collins function
Polarizing fragmentation function
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Sivers effect in SIDIS
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Brodsky, Hwang, Schmidt model for Sivers function
needs k- dependent quark distribution in p?
Sivers function
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M.A., M. Boglione, U.DAlesio, A.Kotzinian, F.
Murgia, A Prokudin
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Deuteron target
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M.A, M. Boglione, U. DAlesio, A. Kotzinian, F.
Murgia, A. Prokudin
hep-ph/0511017
First p- moments of extracted Sivers functions,
compared with models
data from HERMES and COMPASS
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M. Anselmino, M. Boglione, J.C. Collins, U.
DAlesio, A.V. Efremov, K. Goeke, A. Kotzinian,
S. Menze, A. Metz, F. Murgia, A. Prokudin, P.
Schweitzer, W. Vogelsang, F. Yuan
The first and 1/2-transverse moments of the
Sivers quark distribution functions, defined in
Eqs. (3, 9), as extracted in Refs. 20, 21, 23.
The fits were constrained mainly (or solely) by
the preliminary HERMES data in the indicated
x-range. The curves indicate the 1-s regions of
the various parameterizations.
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Collins effect in SIDIS
Spin effect comes from fragmentation of a
transversely polarized quark
initial q spin is transfered to final q', which
fragments
q
q
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Collins effect in SIDIS couples to transversity,
seminar of E. Boglione for combined extraction
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fit to HERMES data on
W. Vogelsang and F. Yuan
Soffer-saturated h1
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A. V. Efremov, K. Goeke and P. Schweitzer (h1
from quark-soliton model)
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COMPASS measured Collins and Sivers asymmetries
for positive (?) and negative (?) hadrons
small values due to deuteron target cancellation
between u and d contributions
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What do we learn from the Sivers distribution?
number density of partons with longitudinal
momentum fraction x and transverse momentum k-,
inside a proton with spin S
M. Burkardt, PR D69, 091501 (2004)
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Total amount of intrinsic momentum carried by
partons of flavour a
for a proton moving along the z-axis and
polarization vector
S
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Numerical estimates from SIDIS data
U. DAlesio
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Sivers function and proton anomalous magnetic
moment
M. Burkardt, S. Brodsky, Z. Lu, I. Schmidt
Both the Sivers function and the proton anomalous
magnetic moment are related to correlations of
proton wave functions with opposite helicities
in qualitative agreement with large z data
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The leading-twist correlator, with intrinsic k-,
contains several other functions .....
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8 leading-twist spin-k- dependent distribution
functions
Courtesy of Aram Kotzinian
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Polarized SIDIS cross section, up to subleading
order in 1/Q
Kotzinian, NP B441 (1995) 234 Mulders and
Tangermann, NP B461 (1996) 197 Boer and Mulders,
PR D57 (1998) 5780 Bacchetta et al., PL B595
(2004) 309 Bacchetta et al., JHEP 0702 (2007) 093
SIDISLAND