Possible Additional Measurements in E906

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Possible Additional Measurements in E906
Jen-Chieh Peng
University of Illinois at Urbana-Champaign
E906 Collaboration Meeting
Fermilab, June 20-21, 2008
Outline

• Azimuthal angular distributions of Drell-Yan
  and J/?
• pd/pp ratios for J/? production
• Nuclear effects of open-charm production
• Recent E866 results ? E906 prospect

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Three parton distributions describing quarks
transverse momentum and/or transverse spin
1) Transversity distribution function
2) Sivers function
3) Boer-Mulders function
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TMD and transversity PDFs are probed in
Semi-Inclusive DIS


Unpolarized
Boer-Mulders
Transversity
Polarized target

Sivers
Polarzied beam and target
SL and ST Target Polarizations ?e Beam
Polarization
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TMD and transversity PDFs are also probed in
Drell-Yan
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Drell-Yan decay angular distributions
T and F are the decay polar and azimuthal angles
of the µ in the dilepton rest-frame
Collins-Soper frame
A general expression for Drell-Yan decay angular
distributions
In general
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Decay Angular Distribution of Naïve Drell-Yan
Data from Fermilab E772
McGaughey, Moss, JCP Annu. Rev. Nucl. Part.
Sci. 49 (1999) 217 (hep/ph-9905409)
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Drell-Yan decay angular distributions
T and F are the decay polar and azimuthal angles
of the µ in the dilepton rest-frame
Collins-Soper frame
A general expression for Drell-Yan decay angular
distributions
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Decay angular distributions in pion-induced
Drell-Yan
NA10 p- W
Z. Phys. 37 (1988) 545
Dashed curves are from pQCD calculations
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Decay angular distributions in pion-induced
Drell-Yan
Is the Lam-Tung relation violated?
140 GeV/c
194 GeV/c
286 GeV/c
Data from NA10 (Z. Phys. 37 (1988) 545)
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Decay angular distributions in pion-induced
Drell-Yan
E615 Data 252 GeV p- W
Phys. Rev. D 39 (1989) 92
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Boer-Mulders function h1-
?10.47, MC2.3 GeV
Boer, PRD 60 (1999) 014012
?gt0 implies valence BM functions for pion and
nucleon have same signs
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Azimuthal cos2F Distribution in pd Drell-Yan
Lingyan Zhu et al., PRL 99 (2007) 082301
With Boer-Mulders function h1- ?(p-W?µµ-X)
valence h1-(p) valence h1-(p) ?(pd?µµ-X)
valence h1-(p) sea h1-(p)
?gt0 suggests same sign for the valence and sea BM
functions
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Extraction of Boer-Mulders functions from pd
Drell-Yan
(B. Zhang, Z. Lu, B-Q. Ma and I. Schmidt,
arXiv0803.1692)
c
3.99 3.83 0.91 -0.96 0.16 0.45 0.79
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Extraction of Boer-Mulders functions from pd
Drell-Yan
(B. Zhang, Z. Lu, B-Q. Ma and I. Schmidt,
arXiv0803.1692)
Fit to the pd Drell-Yan data
Satisfy the positivity bound
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Extraction of Boer-Mulders functions from pd
Drell-Yan
(B. Zhang, Z. Lu, B-Q. Ma and I. Schmidt,
arXiv0803.1692)
c
3.99 3.83 0.91 -0.96 0.16 0.45 0.79
Prediction on the pp Drell-Yan

• It seems unlikely that pd data alone can
  determine the flavor structure of BM functions!
• Additional Drell-Yan data are needed

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Angular Distribution in E866 pp/pd Drell-Yan
Preliminary
Preliminary
Preliminary
Preliminary
PT (GeV/c)
pp and pd Drell-Yan show similar angular
distributions. Should be analysed togther for
better constraints on BM.
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What more could be done in Fermilab E906?
1) Boer-Mulders functions can be measured at
larger x
2) Study Nuclear effects of Boer-Mulders
functions
3) Measure azimuthal angular dependence of J/?
decay
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Nuclear modification of spin-dependent PDF?
EMC effect for g1(x)
Bentz, Cloet et al., arXiv0711.0392
Very difficult to measure !
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Nuclear Dependence of the Boer-Mulders function?
NA10 Z. Phys. C37, 545 (1988)
Open Deuterium Solid Tungsten
We might have a better measurement of the nuclear
effects of the Boer-Mulders function in E906
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Nuclear effects of J/? and ? and open-charm
p A ? J/? or ? at s1/2 38.8 GeV
a(xF) is largely the same for J/? and ?
Universal behavior for a(pT) (similar for J/?,
?)
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Nuclear effects of open-charm production
p A ? D x at s1/2 38.8 GeV
E789 open-aperture, silicon vertex dihadron
detection
hh- mass spectrum (after vertex cut)
No nuclear effect for D production (at xF 0)
D0 ? K- p
Need to extend the measurements to large xF region
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Single muon measurement in E866 pA
Thesis of Stephen Klinksiek
Targets (Z -24.0) 0 Empty 1 0.502
Copper 2 2.036 Beryllium 3 1.004 Copper
High-pT Single Muon Trigger
High-pT single muon events are dominated by
D-meson decays
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Preliminary E866 results on the
single-muon (open-charm) nuclear-dependence
Cu / Be Ratios
PT (GeV/C)
Rapidity (y)
PT and XF (y) dependences have similar trend as
J/?
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A universal xF-dependence in p-A hadron
production?
Kopeliovich et al., hep-ph/0501260
Data cover energy range from 70 to 400 GeV
XF-scaling for a broad energy range ? nuclear
shadowing alone can not explain the data
Do open-charm and quarkonium also follow the same
trend?
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Gluon distributions in proton versus neutron?
Lingyan Zhu et al., PRL, 100 (2008) 062301
(arXiv 0710.2344)
Gluon distributions in proton and neutron are
very similar
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How large is the EMC effect for deuteron?
This can not be extracted from DIS or Drell-Yan
using s(pd)/2s(pp)
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Constraints on the gluon distributions in nuclei
from quarkonium A-dependence
p A ? J/? or ? at s1/2 38.8 GeV
Arleo, arXiv0804.2802
a(xF) is practically flat over the region
-0,1 lt xF lt 0.3
The flat nuclear dependence for gluon
distributions over 0.025 lt x lt 0.12 can put
constraints on some parametrizations
Additional constraints could be provided from
E906 A-dependence measurement
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Future tasks

• Monte-Carlo simulations for the acceptance and
  count rates for these measurements (need to have
  the updated E906 M-C code).
• Triggers required for these measurements.
• Other additional physics in E906.

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Quark-diquark Models for Boer-Mulders Function
h1-

• Initial-state gluon interaction can produce
  nonzero h1- for the proton in the quark-scalar
  diquark model. In this model,
• h1- f1T-.
• Boer,BrodskyHwang, PRD67,054003(2003).
• Recent diquark-spectator model Gamberg, Goldstein
  Schlegel, arXiv 0708.0324.

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Pion Boer-Mulders Function

• Final-state interaction with one gluon exchange
  can produce nonzero h1- for the pion in the
  quark-spectator-antiquark model with constant
  coupling g?.
• LuMa, PRD70,094044(2004).
• The quark-spectator-antiquark model with
  effective pion-quark-antiquark coupling as a
  dipole form factor Lu Ma, hep-ph/0504184

Pion-cloud model gives proton sea-quark BM
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Comparison of data and simulation
Blue simulation Red data (dset8)