presentazione VIQCD

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The proton transverse structure
Mauro Anselmino, Università
di Torino INFN VIQCD Inaugural Meeting
Jülich, 30 November 2007
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Torino group Theory (University INFN)
Mauro Anselmino Mariaelena Boglione Stefano
Melis Alexei Prokudin
http//www.to.infn.it/7Eboglione/spin.html
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The longitudinal structure of nucleons is
simple It has been studied for almost 40 years
DIS
Q2
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Three leading twist partonic distributions (PDF),
in collinear configuration, q(x,Q2), ?q(x,Q2),
?Tq(x,Q2)
Correlator
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Transversity distribution
Transversity decouples from Deep Inelastic
Scattering
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The transverse structure is much more interesting
and less studied (not only because of
transversity)
orbiting quarks?
spin-k- correlations?
Space dependent distribution functions
Transverse Momentum Dependent distribution
functions
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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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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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How and what do we know about TMDs and what do we
learn from them?
TMDs in SIDIS
Single Spin
Asymmetries (SSA) in SIDIS Sivers
functions Collins function from ee-
unpolarized processes (Belle) and first
extraction of transversity SSA in hadronic
processes Future measurements and transversity
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Main source of information on transverse nucleon
structure
SIDIS kinematics according to Trento conventions
(2004)
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SIDIS in parton model with intrinsic k-
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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
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Azimuthal dependence induced by quark intrinsic
motion
EMC data, µp and µd, E between 100 and 280 GeV
M.A., M. Boglione, U. DAlesio, A. Kotzinian, F.
Murgia and A. Prokudin
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Transverse single spin asymmetries in SIDIS,
experimentally observed
in collinear configurations there cannot be (at
LO) any PT
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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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Sivers function
Boer-Mulders function
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Spin-k- correlations in fragmentation process
(case of final spinless hadron)
Collins function
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Large K asymmetry!
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Present knowledge of Sivers function (u,d)
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. 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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Numerical estimates from SIDIS data
U. DAlesio
Valence quark dominance?
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TMDs and SSAs in hadronic collisions

factorization theorem (?)
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excellent agreement with data for unpolarized
cross section, but no SSA
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BNL-AGS vs 6.6 GeV 0.6 lt pT lt 1.2
E704 vs 20 GeV 0.7 lt pT lt 2.0
observed transverse Single Spin Asymmetries
E704 vs 20 GeV 0.7 lt pT lt 2.0
experimental data on SSA
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STAR-RHIC vs 200 GeV 1.2 lt pT lt 2.8
and AN stays at high energies .
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SSA can be understood with parton intrinsic
motion and TMDs
E704 data
STAR data
prediction
fit
U. DAlesio, F. Murgia
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Predictions for PAX at HESR (FAIR)
predictions based on Sivers functions from E704
data
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TMDs and SSAs in Drell-Yan processes

factorization holds, two scales, M2, and qT
D-YLAND, similar to SIDISLAND
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Unpolarized cross section already very interesting
Collins-Soper frame
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(Polarized) Drell-Yan cross processes allow to
access many TMDs (Boer-Mulders, )
D-YLAND verify whether and offer the golden
channel to measure the transversity distribution

crucial QCD test
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(PAX experiment)
Ideal for optimising cross section and probing
valence quark region. ATT predicted to be large
and safe from pQCD corrections
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l
l
q
q
J/?
l
l
q
q
all vector couplings, same spinor structure
and, at large x1, x2
measure ATT also in J/? resonance region
M. A., V. Barone, A. Drago and N. Nikolaev
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Turin group for custom pixel detector in PANDA

• INFN, Sezione di Torino
• Daniela Calvo
• Paolo De Remigis
• Alessandro Feliciello
• Alessandra Filippi
• Gianni Mazza
• Angelo Rivetti
• Richard Wheadon
• Dipartimento di Fisica Sperimentale, Università
  di Torino
• and INFN, Sezione di Torino
• Elena Botta
• Tullio Bressani
• Francesca De Mori
• Simonetta Marcello

Torino group experiment
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PANDA Experiment Features

• Excellent forward acceptance and resolution
• Dynamic range of particle momenta 0.1 - 8
  GeV/c
• Momentum resolution (Dp/p ? 1)
• Particle ID for e?, m?, p?, K?, p,
• Electromagnetic calorimeter g, p0, h ...
  (e?)
• High-resolution vertex detection D?, D0 /
  Ks, ?, S, O ...
• High interaction rate up to 2107 s-1
• Triggerless data acquisition at high rates

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Micro-Vertex Detector in PANDA

• resolution and triggering of D decays need
  spatial resolution of better than 100 mm

D0 -gt ct 123.7 mm (56 ? 5) K?
anything (42 ? 5) K0 K0 anything
15 cm
D? -gt ct 315 mm (30 ? 4) K?
anything (59 ? 7) K0 K0 anything
(c c ) also have considerable branching ratios
involving KK

• Tagging of the charm usually refers to offline
  identification of displaced decay vertex
• faster identification in PANDA ?

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Micro-Vertex-Detector

• good spatial resolution in r-phi for momentum
  measurement of soft pions coming from D decays
• good spatial resolution especially in z for
  D-Tagging
• good time resolution with DC beam (107
  annihilations / s)
• triggerless readout
• discrimination of particles by means of energy
  loss measurements
• low material budget (due to low momentum
  particles)
• fluence of 4 10 13 n 1MeV eq/cm2 for year
• (half year data taking) for p-p at 15 GeV/c

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Custom silicon pixel detector

• Standard hybrid technology
• thin pixel sensors realized with epitaxial
  silicon material
• pixel FEE developed with the 130 nm CMOS
  technology

Several depositions for defining geometry and
for obtaining pixel sensors are made on this side
15 cm
r 50 Wcm or more
25 150 mm
epitaxial silicon layer
silicon Cz substrate
Some hundreds of mm
r 0.01 0.02 Wcm
The thinning starts from this side and stops to
ten mm (or more) from the epitaxial silicon
layer
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Epitaxial silicon diodes in the bibliography

• high tolerance to radiation (no type inversion up
  to 1016 n/cm2 and 81015 p/cm2)

G.Kramberger et al.,Superior radiation tolerance
of thin epitaxial silicon detectors, NIM A 515
(2003) 665-670
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Work to be done

• Study and test of the epitaxial material and
  sensor wafers
• Test of some hybrid pixel assemblies in epitaxial
  material
• Study of the readout architecture based on 130 nm
  CMOS technology
• Test of readout circuit prototype

Thanks!
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The mother of all functions M. Diehl, Trento
workshop, June 07
Wigner function
(Belitsky, Ji, Yuan)
GPDs
TMDs