Diese Präsentation wurde erfolgreich gemeldet.
Wir verwenden Ihre LinkedIn Profilangaben und Informationen zu Ihren Aktivitäten, um Anzeigen zu personalisieren und Ihnen relevantere Inhalte anzuzeigen. Sie können Ihre Anzeigeneinstellungen jederzeit ändern.
Francesca Giordano for the Phenix Collaboration
Spin 2014, Beijing, China, October 21st, 2014
Proton Quark Helicity Struct...
Francesca Giordano
The proton spin puzzle
quark spins gluon spins
quark&gluon
orbital motion
1
2
⇥
G
Lq
Lg
D. De Florian e...
Francesca Giordano
The proton spin puzzle
quark spins gluon spins
quark&gluon
orbital motion
D. De Florian et al., PRL101,...
Francesca Giordano
The proton spin puzzle
quark spins gluon spins
quark&gluon
orbital motion
D. De Florian et al., PRL101,...
Francesca Giordano
The proton spin puzzle
quark spins gluon spins
quark&gluon
orbital motion
D. De Florian et al., PRL101,...
Francesca Giordano
The proton spin puzzle
quark spins gluon spins
quark&gluon
orbital motion
D. De Florian et al., PRL101,...
Francesca Giordano
The proton spin puzzle
quark spins gluon spins
quark&gluon
orbital motion
D. De Florian et al., PRL101,...
Francesca Giordano
The proton spin puzzle
quark spins gluon spins
quark&gluon
orbital motion
D. De Florian et al., PRL101,...
Francesca Giordano
Hadron-Hadron collider
√s of 62 GeV, 200 GeV, 500 GeV
RHIC
1
Identified Forward Hadrons
in p +p at RHIC...
Francesca Giordano
South Muon Tracker
North Muon Tracker
Proton Proton
PHENIX IR
µ
e
10Francesca Giordano
Francesca Giordano
PHENIX
Central Arms
Central Arms:
Tracking, Momentum and PID for:
★ charged and neutral hadrons
★ direc...
Francesca Giordano
Phenix 500 Gev Runs
W production in proton-proton collision at 500 (510) GeV
High Longitudinal Polariza...
Francesca Giordano 13
Decay lepton kinematics
Pythia
ll ?
d ¯d¯u u
Forward ForwardBackward Backward
Francesca Giordano
Jacobian peaks at central rapidities! Suppressed/no Jacobian peaks
at forward rapidities!
14
Decay lept...
Francesca Giordano
W asymmetries in central
rapidities
15
Francesca Giordano
W decay at central rapidities
Jacobian peaks visible!
Analysis strategy:
1. Reduce background as much a...
Francesca Giordano
W decay at central rapidities
Jacobian peaks visible!
Analysis strategy:
1. Reduce background as much a...
Francesca Giordano
W decay at central rapidities
Jacobian peaks visible!
Analysis strategy:
1. Reduce background as much a...
Francesca Giordano
W decay at central rapidities
Jacobian peaks visible!
Analysis strategy:
1. Reduce background as much a...
Francesca Giordano
W decay at central rapidities
Jacobian peaks visible!
Analysis strategy:
1. Reduce background as much a...
Francesca Giordano
W asymmetries in forward
rapidities
21
Francesca GiordanoFigure 1.2: Top plots: Real muon cross sections for positive (left) and negative (right) muons
tions and...
Francesca Giordano
3 types of Backgrounds:
1. Muon background: open-heavy flavor decay, quarkonia, Drell-Yan
Background fro...
Francesca Giordano
3 types of Backgrounds:
1. Muon background: open-heavy flavor decay, quarkonia, Drell-Yan
2. Punch-throu...
Francesca Giordano
3. Fake high-pT muons
3 types of Backgrounds:
1. Muon background: open-heavy flavor decay, quarkonia, Dr...
Francesca Giordano
3. Fake high-pT muons
3 types of Backgrounds:
1. Muon background: open-heavy flavor decay, quarkonia, Dr...
Francesca Giordano
Analysis strategy:
1. Muon Trigger upgrade
2. Reduce background as much as possible
3. Estimate signal-...
Francesca Giordano
Phenix Forward Upgrade
PYTHIA
W
old trigger
28
Phenix upgraded the existing muon arms
for a dedicated m...
Francesca Giordano
Phenix Forward Upgrade
29
MuTracker FEE upgrades
1. Add momentum info in the trigger
TOP view
Reject mu...
Francesca Giordano
Definining the W-ness of an event
Signal likelihood based on probability density
functions from simulate...
Francesca Giordano
Definining the W-ness of an event
W likelihood ratio extraction and background estimation Data Analysis
...
Francesca Giordano
Definining the W-ness of an event
Signal likelihood based on probability density
functions from simulate...
Francesca Giordano
Extraction of the Sig/Bg ratio
via an Extended Unbinned, 2-D, Maximum-Likelihood fit
(2D EUMLF)
pseudora...
Francesca Giordano
Extraction of the Sig/Bg ratio
34
via an Extended Unbinned, 2-D, Maximum-Likelihood fit
(2D EUMLF)
param...
Francesca Giordano
Extraction of the Sig/Bg ratio
Sig/Bg ratio from 30% to 50%, depending on
Phenix arm/muon charge/ỷ regi...
Francesca Giordano
W cross-section
Consistent with prediction within
the large uncertainties
36
Francesca Giordano
W cross-section: systematics
37
About 20% charge
misidentification
Momentum smearing
Muon bg estimate
2D...
Francesca Giordano
Single Spin Asymmetries
Background AL
consistent with 0
Background treated as a
dilution in the measure...
Francesca Giordano
Single Spin Asymmetries
AL =
1
P
N+
N
N+ + N
39
Phenix AL for W+ decay leptons appear to
be consistent ...
Francesca Giordano
Summary
About 300 pb-1 at 500 GeV collected at Phenix for W!l𝜈
All data analyzed
40
W!e+- in central ra...
Francesca Giordano
Single Spin Asymmetries
AL =
1
P
N+
N
N+ + N
41
Results from 2013 data compatible with
previous results...
Francesca Giordano
Single Spin Asymmetries
ỷ dependence:
Large uncertainties, similar conclusions
42
Phenix AL for W+ deca...
Nächste SlideShare
Wird geladen in …5
×

F Giordano Proton Spin from Sea Quarks

Measurement to access the contribution to the Proton Spin from Quarks, in particular Sea Quarks

  • Loggen Sie sich ein, um Kommentare anzuzeigen.

  • Gehören Sie zu den Ersten, denen das gefällt!

F Giordano Proton Spin from Sea Quarks

  1. 1. Francesca Giordano for the Phenix Collaboration Spin 2014, Beijing, China, October 21st, 2014 Proton Quark Helicity Structure via W-boson Production in pp Collision @ PHENIX 1
  2. 2. Francesca Giordano The proton spin puzzle quark spins gluon spins quark&gluon orbital motion 1 2 ⇥ G Lq Lg D. De Florian et al., PRL101, 072001 (2008) 2
  3. 3. Francesca Giordano The proton spin puzzle quark spins gluon spins quark&gluon orbital motion D. De Florian et al., PRL101, 072001 (2008) precise (quark + antiquark) PDFs extracted mostly from Deep Inelastic Scattering experiments in DIS, flavor separation is bound to the knowledge of fragmentation functions leading to larger uncertainties 3
  4. 4. Francesca Giordano The proton spin puzzle quark spins gluon spins quark&gluon orbital motion D. De Florian et al., PRL101, 072001 (2008) There is an alternative! W production in proton-proton collision! 4
  5. 5. Francesca Giordano The proton spin puzzle quark spins gluon spins quark&gluon orbital motion D. De Florian et al., PRL101, 072001 (2008) Maximally parity-violating! Independent from Fragmentation Functions There is an alternative! W production in proton-proton collision! 5 W+ W dL ¯uR ¯dR uL
  6. 6. Francesca Giordano The proton spin puzzle quark spins gluon spins quark&gluon orbital motion D. De Florian et al., PRL101, 072001 (2008) There is an alternative! AL = 1 P N+ N N+ + N W production in proton-proton collision! 6 W+ W dL ¯uR ¯dR uL
  7. 7. Francesca Giordano The proton spin puzzle quark spins gluon spins quark&gluon orbital motion D. De Florian et al., PRL101, 072001 (2008) There is an alternative! W production in proton-proton collision! 7 AW + L = u(x1) ¯d(x2) + ¯d(x1)u(x2) u(x1) ¯d(x2) + ¯d(x1)u(x2) AW L = d(x1)¯u(x2) + ¯u(x1)d(x2) d(x1)¯u(x2) + ¯u(x1)d(x2)
  8. 8. Francesca Giordano The proton spin puzzle quark spins gluon spins quark&gluon orbital motion D. De Florian et al., PRL101, 072001 (2008) There is an alternative! W production in proton-proton collision! 8
  9. 9. Francesca Giordano Hadron-Hadron collider √s of 62 GeV, 200 GeV, 500 GeV RHIC 1 Identified Forward Hadrons in p +p at RHIC J.H. Lee for Collaboration BNL April 27, DIS09, Madrid STAR PHENIX @ RHIC 9Francesca Giordano
  10. 10. Francesca Giordano South Muon Tracker North Muon Tracker Proton Proton PHENIX IR µ e 10Francesca Giordano
  11. 11. Francesca Giordano PHENIX Central Arms Central Arms: Tracking, Momentum and PID for: ★ charged and neutral hadrons ★ direct photons ★ e+ e- |⌘| < 0.35 Forward Arms 1.2 < |⌘| < 2.4 Tracking, Momentum and PID for e± 11 Tracking and Momentum for µ± ~pp ! W± ! e± ⌫ ~pp ! W± ! µ± ⌫
  12. 12. Francesca Giordano Phenix 500 Gev Runs W production in proton-proton collision at 500 (510) GeV High Longitudinal Polarization (up to 56%) Total luminosity: 300 pb-1 Central arms: - Results being finalized Forward Arms: - Preliminary results on 2011 and 2012 data - 2013 data preliminary New! 12
  13. 13. Francesca Giordano 13 Decay lepton kinematics Pythia ll ? d ¯d¯u u Forward ForwardBackward Backward
  14. 14. Francesca Giordano Jacobian peaks at central rapidities! Suppressed/no Jacobian peaks at forward rapidities! 14 Decay lepton kinematics
  15. 15. Francesca Giordano W asymmetries in central rapidities 15
  16. 16. Francesca Giordano W decay at central rapidities Jacobian peaks visible! Analysis strategy: 1. Reduce background as much as possible 2. Extract the Bg shape then fit the whole spectrum together with a signal shape 3. Evaluate asymmetries 16 W+W-
  17. 17. Francesca Giordano W decay at central rapidities Jacobian peaks visible! Analysis strategy: 1. Reduce background as much as possible Background 4/29/2014 PHENIX W->e | Ciprian Gal 6 • Reducible Backgrounds: – Photons from neutral pion/eta decays followed by e± pair production – Cosmic rays – Beam related backgrounds • Irreducible Backgrounds – Z decays – Charm, bottom decays – Other W decays ative isolation cut und discriminator ne of R=0.4 divided he candidate background reduced by a factor 10! Main background discriminator: Relative isolation cut: energy in a cone (R=0.4rad) not from the candidate electron < 10% 17 Background sources: 1. e±-pair production by 𝛑0 /ỷ decay photons 2. cosmic rays 3. background from beams 4. Z/charm-bottom decays/other W decays
  18. 18. Francesca Giordano W decay at central rapidities Jacobian peaks visible! Analysis strategy: 1. Reduce background as much as possible 2. Extract the Bg shape then fit the whole spectrum together with a signal shape uses the low pT (background dominated) spectra used to define the shape of the background 18 Assumption 1: background shape does not change at higher pT Assumption 2: smooth curve to describe background Gaussian process regression extrapolate the expected bg shape and uncertainty in the higher pT region Gaussian Process Regression 4/29/2014 PHENIX W->e | Ciprian Gal 11 • Use background control region to get a shape • The GPR will give a background contribution and uncertainty • A cross check of the method has been performed with a classic functional form showing good agreement Gaussian Process Regression 4/29/2014 PHENIX W->e | Ciprian Gal 11 • Use background control region to get a shape • The GPR will give a background contribution and uncertainty • A cross check of the method has been performed with a classic functional form showing good agreement
  19. 19. Francesca Giordano W decay at central rapidities Jacobian peaks visible! Analysis strategy: 1. Reduce background as much as possible 2. Extract the Bg shape then fit the whole spectrum together with a signal shape 19 Fit the extracted bg shape + signal W+W-
  20. 20. Francesca Giordano W decay at central rapidities Jacobian peaks visible! Analysis strategy: 1. Reduce background as much as possible 2. Extract the Bg shape then fit the whole spectrum together with a signal shape 3. Evaluate asymmetries Asymmetries all data • Run 13 results were separated into two eta bins • Run 09/11/12 data all combined into one single measurement • Overall consistency with the theoretical predictions Good agreement with prediction 2009+2011+2012 2013 Final results will be submitted soon 20
  21. 21. Francesca Giordano W asymmetries in forward rapidities 21
  22. 22. Francesca GiordanoFigure 1.2: Top plots: Real muon cross sections for positive (left) and negative (right) muons tions and Analysis Variables MC simulations of signal and ba 22 W decay at forward rapidities Large Background ! Muon cross-section dominated by W only at high pT! Pythia W+W-
  23. 23. Francesca Giordano 3 types of Backgrounds: 1. Muon background: open-heavy flavor decay, quarkonia, Drell-Yan Background from other than W muon sources only part of the story! Figure 1.2: Top plots: Real muon cross sections for positive (left) and negative (right) muons tions and Analysis Variables MC simulations of signal and ba 23 W decay at forward rapidities Pythia W+W-
  24. 24. Francesca Giordano 3 types of Backgrounds: 1. Muon background: open-heavy flavor decay, quarkonia, Drell-Yan 2. Punch-through Hadrons: from W and other sources - in principle at low pT, but muon arms have large momentum smearing ! Background from other than W muon sources only part of the story! MC simulations of signal and backgrounds Simulations and Analysis Variables Figure 1.3: Top plots: Hadronic cross sections for positive (left) and negative (right)hadrons MC simulations of signal and backgrounds Simulations and Analysis Va 24 Pythia W decay at forward rapidities
  25. 25. Francesca Giordano 3. Fake high-pT muons 3 types of Backgrounds: 1. Muon background: open-heavy flavor decay, quarkonia, Drell-Yan 2. Punch-through Hadrons: from W and other sources - in principle at low pT, but muon arms have large momentum smearing ! Background from other than W muon sources only part of the story! 25 W decay at forward rapidities
  26. 26. Francesca Giordano 3. Fake high-pT muons 3 types of Backgrounds: 1. Muon background: open-heavy flavor decay, quarkonia, Drell-Yan 2. Punch-through Hadrons: from W and other sources - in principle at low pT, but muon arms have large momentum smearing ! Background from other than W muon sources only part of the story! MC simulations of signal and backgrounds Simulations and Analysis Variables Total background, accounting for all sources and smearing: 26 W decay at forward rapidities W+W-
  27. 27. Francesca Giordano Analysis strategy: 1. Muon Trigger upgrade 2. Reduce background as much as possible 3. Estimate signal-to-background ratio 4. Evaluate asymmetries MC simulations of signal and backgrounds Simulations and Analysis Variables Total background, accounting for all sources and smearing: W- W+ 27 W decay at forward rapidities
  28. 28. Francesca Giordano Phenix Forward Upgrade PYTHIA W old trigger 28 Phenix upgraded the existing muon arms for a dedicated muon-from-W trigger!
  29. 29. Francesca Giordano Phenix Forward Upgrade 29 MuTracker FEE upgrades 1. Add momentum info in the trigger TOP view Reject muons with momentum <15 GeV Phenix upgraded the existing muon arms for a dedicated muon-from-W trigger! Add precise timing information 1. to reject out of time background 2. to correlate events with beam polarization 1 beamclock! 2. Addition of 4 new RPC stations Signal Bg from beams FVTX
  30. 30. Francesca Giordano Definining the W-ness of an event Signal likelihood based on probability density functions from simulated W events Wness = signal signal + bg yields for negativemuon candidates as a function of the kinematic = [p(DG0, DDG0), p(DCA), p( 2 ), p(RPC DCA), p(FV TX match), p(FTV X cone)] 30 Background likelihood based on pdfs from bg-dominated data (signal < 1%) Unlikely a W-event Very likely a W-event
  31. 31. Francesca Giordano Definining the W-ness of an event W likelihood ratio extraction and background estimation Data Analysis High-efficiency cut parameter! Signal likelihood based on probability density functions from simulated W events Background likelihood based on pdfs from bg-dominated data (signal < 1%) Wness = signal signal + bg = [p(DG0, DDG0), p(DCA), p( 2 ), p(RPC DCA), p(FV TX match), p(FTV X cone)] 31
  32. 32. Francesca Giordano Definining the W-ness of an event Signal likelihood based on probability density functions from simulated W events Background likelihood based on pdfs from bg-dominated data (signal < 1%) Wness = signal signal + bg = [p(DG0, DDG0), p(DCA), p( 2 ), p(RPC DCA), p(FV TX match), p(FTV X cone)] 32 Cut chosen: Wness > 0.99 fixed looking at the FOM of uncertainties (stat+sys) for the final asymmetries
  33. 33. Francesca Giordano Extraction of the Sig/Bg ratio via an Extended Unbinned, 2-D, Maximum-Likelihood fit (2D EUMLF) pseudorapidity ỷ effective bending dw23 (Independent from the variables used in the wness estimation) 33
  34. 34. Francesca Giordano Extraction of the Sig/Bg ratio 34 via an Extended Unbinned, 2-D, Maximum-Likelihood fit (2D EUMLF) parameters fixed for W from Simulation for Hadron bg & Fake muons extrapolated from bg-dominated data (low-wness) for Muon bg from Simulation dw23ỷ
  35. 35. Francesca Giordano Extraction of the Sig/Bg ratio Sig/Bg ratio from 30% to 50%, depending on Phenix arm/muon charge/ỷ region 35 via an Extended Unbinned, 2-D, Maximum-Likelihood fit (2D EUMLF)
  36. 36. Francesca Giordano W cross-section Consistent with prediction within the large uncertainties 36
  37. 37. Francesca Giordano W cross-section: systematics 37 About 20% charge misidentification Momentum smearing Muon bg estimate 2D-EUMLF accuracy (tested with MC inputs) Major contributions: Trigger efficiency All uncertainties propagated to the asymmetries via sig/bg fit uncertainty
  38. 38. Francesca Giordano Single Spin Asymmetries Background AL consistent with 0 Background treated as a dilution in the measured AL 38 AL = 1 P N+ N N+ + N
  39. 39. Francesca Giordano Single Spin Asymmetries AL = 1 P N+ N N+ + N 39 Phenix AL for W+ decay leptons appear to be consistent with prediction at center and forward rapidities At backward rapidities AL seems to be positive/consistent with zero (similarly to the AL observed from STAR for positive electrons AL) Phenix AL for W- decay leptons are qualitatively consistent with predictions
  40. 40. Francesca Giordano Summary About 300 pb-1 at 500 GeV collected at Phenix for W!l𝜈 All data analyzed 40 W!e+- in central rapidities: final results and paper in advance stage,will be submitted soon W!µ+- in forward rapidities: preliminary results for run 2013 presented here for the first time Work in progress to reduce systematics: - improve signal to background extraction - new data production to correct for known momentum smearing and improve the charge reconstruction Thank you!
  41. 41. Francesca Giordano Single Spin Asymmetries AL = 1 P N+ N N+ + N 41 Results from 2013 data compatible with previous results (2012 data)
  42. 42. Francesca Giordano Single Spin Asymmetries ỷ dependence: Large uncertainties, similar conclusions 42 Phenix AL for W+ decay leptons appear to be consistent with prediction at center and forward rapidities At backward rapidities AL seems to be positive/consistent with zero (similarly to the AL observed from STAR for positive electrons AL) Phenix AL for W- decay leptons are qualitatively consistent with predictions AL = 1 P N+ N N+ + N

×