Charm in AuAu200 with Silicon Run-7 (2007) BNL, KENT, NANTESBNL, March Intro X-section work Flow work

When Yuri and I proposed the ‘swan song’ for Silicon Run-7 AuAu200, we estimated a significance of sigma. Silicon did not behave as expected but we still have a 10 sigma signal sum for near mbias. It would be nice if we get (at least) one Silicon publication

1 st Production 35 Million Events (~60 Millions full/raw in 2007) Single step Background subtraction Need to study systematics of Background (++--, rot, mixed) Significance should allow for smaller errors in x-sections/flow. D0+D0bar

4 Invariant mass of D 0 and D 0 bar separately Ratio of D 0 bar/D 0 = /-.19(stat.) Uncorrected raw yield Au+Au at  s=200GeV Uncorrected raw yield Au+Au at  s=200GeV STAR PRELIMINARY Compatible with vanishing  B (consistency check)

Charm Cross-Section Comparison at 200 GeV NLO Ref: R. Vogt, arXiv: v1 [hep-ph] PHENIX: S. Adler, et al. Phys. Rev. Lett (2005) S. Adler, et al. Phys. Rev. Lett (2005) STAR: C. Adler, et al. Phys. Rev. Lett (2003) S. Baumgart, arXiv:nucl-ex/ Y. Zhang, arXiv:nucl-ex/ STAR There are still unresolved discrepancies between STAR and PHENIX

X – Section / R CP

We need, basically, two things: A handle on centrality (usually done via gRefMult) A p T spectrum, normalized and corrected

Au+Au data set 3 rd production – Summary of changes  With D 0 and D 0 -bar information saved, plus ++,-- pairs  Calculation of v2 (flow) (save Event plane, D0 phi angle).  Select only Triggered Events (Pile-up events are removed).  Tracks with SiHits>1 are selected  gRefMult properly calculated/saved  Radius of Silicon Hits added to the tuple.  dEdx cut was modified: |n σ K |<2.5 and |n σ π |< 2.5  Relaxed the cut on track pseudorapidity to|η|<1.2 and added a cut on rapidity of D0 (|Rapidity|<1). Au+Au data set 3 rd production – Summary of changes  With D 0 and D 0 -bar information saved, plus ++,-- pairs  Calculation of v2 (flow) (save Event plane, D0 phi angle).  Select only Triggered Events (Pile-up events are removed).  Tracks with SiHits>1 are selected  gRefMult properly calculated/saved  Radius of Silicon Hits added to the tuple.  dEdx cut was modified: |n σ K |<2.5 and |n σ π |< 2.5  Relaxed the cut on track pseudorapidity to|η|<1.2 and added a cut on rapidity of D0 (|Rapidity|<1). J. Joseph, UCLA 2010

Centrality definition in two Productions 1 st Production scaled by 1/N 2 3 rd Production Some ‘gRefMult’ was saved in 1 st prod in each D0 candidate (same Ttree) Assuming background scaling ~N 2 it can be taken out and compared to 3 rd production one

3 rd Prod. 1 st Prod. Scaling factor = % 20%

1 st Prod. 10% 20% Translation between 1 st – 3 rd prod can be done (till 3 rd done!) it breaks for very peripheral event

MC Glauber 3 rd Production 3 rd /Glauber ‘agree’ with some scaling Anthony’s recipe can be applied (next page)

The blue line in the right panel is a simple power-law parameterization with the following form: Anthony’s page

# Hiroshi’s page

D0 - p T

D0 p T is done by subtracting from central mass peak (signal) the normalized sum of the two side bands (background)

1 st Production

1/N EVENTS 1/p T dN/dp T p T (GeV/c) Uncorrected p T spectra for D0+D0bar in |y|<1 We have the embedding to do corrections

Jaiby’s plot from embedding here

Embedding - Monitoring/micro-tuning efficiency

Run-7 Embedding Bad days Embedding - Monitoring/micro-tuning

D0 - FLOW

QYQY QXQX  r (radians) QXQX QYQY 3 rd Production These are average pictures of re-centering done in 4 centrality bins

QYQY QXQX QYQY QXQX  r (radians) 3 rd Production

To be continued next week some time …..

Summary

BackUp

Vertex fit gives more that factor of two better resolution, compared to simple helix swim Important in an exponential falling variable FIT Secondary vertex resolution plots (X, Y, Z) J. Vanfossen

Cuts from previous production 2007 Production MinBias Cuts in New Production EVENT level triggerId : , , Primary vertex position along the beam axis : |zvertex| < 10 cm Resolution of the primary vertex position along the beam axis: |  zvertex |< 200µm TRACKS level Number of hits in the vertex detectors : SiliconHits>2 (tracks with sufficient DCA resolution) Momentum of tracks p >.5GeV/c Transverse Momentum of tracks p T >.5GeV/c Number of fitted TPC hits > 20 Pseudo-rapidity : |  |<1 (SSD acceptance) dEdxTrackLength>40 cm DCA to Primary vertex (transverse), DCA xy <.1 cm EVENT level triggerId : , , Primary vertex position along the beam axis : |zvertex| < 10 cm Resolution of the primary vertex position along the beam axis: |  zvertex |< 200µm TRACKS level Number of hits in the vertex detectors: SiliconHits>1 Transverse Momentum of tracks p T >.5GeV/c Ratio TPC hits Fitted/Possible > 0.51 Pseudo-rapidity : |  |<1.2 dEdxTrackLength>40 cm DCA to Primary vertex (transverse), DCA xy <.2 cm Radius of first hit on track : < 9 cm if number of silicon hits =2 < 13 cm else D 0 candidate |y(D 0 )|<1 |cos(  *)|<0.8 cut changed new cut J. Joseph, UCLA 2010

Cuts from previous production Continued.. Cuts in New Production DECAY FIT level Probability of fit >0.1 && |sLength|<.1cm Particle ID : ndEdx : |n  K |<2, |n  π |<2 DECAY FIT level Probability of fit >0.01 && |sLength|<.1cm Particle ID : ndEdx : |n  K |<2.5, |n  π |<2.5 Particle identification : ndEdx : |n  K |<2, |n  π |<2 |cos(  *)|<0.6 DCA daughters < 300 µm In both productions we made a pico file for further analysis. Cuts Used for making a pico file Previous Production New Production |D0Eta|<1.85 |Cos(θ*)<0.6 J. Joseph, UCLA 2010

3 rd Production

1 st Production