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Prospects for X(3872) Detection at Panda

Prospects for X(3872) Detection at Panda Jens Sören Lange, Martin Galuska, Thomas Geßler, Wolfgang Kühn, Stephanie Künze, Yutie Liang, David Münchow, Björn Spruck, Matthias Ullrich, and Marcel Werner II. Physikalisches Institut, Justus-Liebig-Universität Gießen for the PANDA Collaboration.

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Prospects for X(3872) Detection at Panda

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  1. Prospects for X(3872) Detection at Panda Jens Sören Lange, Martin Galuska, Thomas Geßler, Wolfgang Kühn, Stephanie Künze, Yutie Liang, David Münchow, Björn Spruck, Matthias Ullrich, and Marcel WernerII. Physikalisches Institut, Justus-Liebig-Universität Gießen for the PANDA Collaboration This talk:only MC 12th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon05/31-06/04, 2010College of William and MaryWilliamsburg, Virginia

  2. Belle, Phys. Rev. Lett.91(2003)262001 CDF-II, Phys. Rev. Lett.93(2004)072001 D0, Phys. Rev. Lett.93(2004)162002 BaBar, Phys. Rev. D71(2005)071103 The X(3872) • A charmonium(-like) state found inX(3872) → J/+− • Observation of decay into J/→ C=+1 • interesting properties:breaks isospin in the decaysJ/(!+−), J/(!+−0)→ is it charmonium? • Within  m < 1 MeV of the DD* thresholdS-wave molecular state? • (to be) investigated at Belle, BaBar, CDF-II, D0BES-III, Belle-II • However:width is unknown<2.3 MeV (Belle) Belle

  3. Charmonium Production inpp collisions • X(3872) has C=+ • In e+e− collisions only JPC=1–− can be produced directlyinpp collisions any quantum number • Resonance scan with a cooled anti-proton beam: the width of the X(3872) could be measured !Panda Experiment at FAIR 2 gluons: 0−+, 0++, 2++ J=0,2 3 gluons: 1−−, 1+− J=1

  4. GSI today Future facility 2R=1.084 km

  5. HESR (High Energy Storage Ring) For Anti-Protons • High intensity mode • (stochastic cooling) • High resolution mode • (e–cooling) PANDA • Internal targets • Pellets • Cluster jet • Nuclei: Be, C, Si, Al ' 2 x 109J/ per year

  6. The Pellet Target Here: WASA Target d=25 m fall speed ¸ 60 m/s

  7. Example of Charmonium Width Measurements  (J/) = 99 § 12 § 6 keV  (´) = 306 § 36 § 16 keV by FERMILAB E760 and E835 beam momentum resolution p/p‚ 2 £ 10−4 → s FWHM resolution 0.5 MeV £ BR (J/) ' 630 nb Phys. Rev. D 47(1993)772 30 Events/Luminosity (nb) J/ 25 20 15 10 5 Events/Luminosity (nb) 5 ´ 4 3 2 1

  8. Panda Experiment MVD Micro Vertex Detector TPC Time Projection Chamber EMC Electromagnetic Calorimeter

  9. PandaRoot Framework • Simulation,DigitizationReconstruction,Analysis • 43,000 geometry volumes • ¸400,000 lines of C++ code • Transport engines:Geant3, Geant4, FLUKA • Event Generators:EvtGen, DPM, PYTHIA, UrQMD • ¸20 Linux platforms • Improvements since Panda Physics BookarXiv:0903.3905 • X(3872) simulations for the 1st time • field maps • track finder and track fitter • final state radiation PHOTOS, Comp. Phys. Comm. 79(1994)291-308 For further informationhttp://panda-wiki.gsi.de/cgi-bin/view/Computing/PandaRoot

  10. PandaRoot Implementation of relevant Detectors TPC135 padrows 135,169 pads of 2x2 mm2 • MVD • 120 pixel modules • 100x100 µm2 pixel size • ~107 readout channels • 400 strip modules • ~0.5 m2 active area • 7x104 readout channels EMC ~17,200 crystals PbWO4 (radiation hard, fast decay~6 ns) 28 X0

  11. Estimated Rates for X(3872) Formation at Panda • pbeam=6.99100 GeV/c • Baseline assumption: peak = 50 nb • If X is a loosely bound DD* state Chen, Ma, Phys. Rev. D77(2008)097501cross section estimate ·443 nb • Branching fractions of decays of X(3872) into DD* : J/+− : J/assumed as 9:1:0 • J/! e+ e− and +−BR ' 6% each • Reconstruction efficiency ' 50%(track reconstruction efficiency for low momentum § )! 250 pb • high resolution mode p/p =10−5 is low luminosity mode: L=2£1031 cm−2 s−1 • duty factor = 50% • L int= 0.86 pb−1/day • 20 points for resonance scan2 days/point • Yield '215 events of X! J/+− per day at peak

  12. X(3872)! J/+– Event, PandaRoot Simulation Targetpipe Beampipe e§ § e§ Beampipe § Targetpipe

  13. X(3872) Events in Panda MVD+TPC PandaRoot Simulation XYZ coordinates / cm XYZ coordinates / cm BeampipeInteraction XYZ coordinates / cm

  14. Comparison of e+ e− and +− final states 2-particle invariant mass CombinatorialBackground only Radiative Tail due to Final state radiation(PHOTOS)

  15. Particle Indentification (PID) Using EEMC/ptrack(requires track-cluster matching) EEMC is deposited cluster energy Ptrack is reconstructed track momentum (TPC + MVD) ´ → J/+−, no J/ decay

  16. Example MC Results for X(3872)! J/+− 2-particle invariant mass 4-particle invariant mass without PID X(3872) J/ with PID

  17. Variation of Angular Distributions • Panda is fixed target experiment • Negligible effect on reconstruction efficiency (<1%) • ! Lorentz boost dominates acceptance vector → vector+ pseudoscalar+ pseudoscalar phasespace

  18. Kinematic Fit: Vertex Constraint and Mass Constraint Example: reference mode ´!J/+– J/ ‘ No fit No fit Constraint ‘ J/ Fit Fit m'3 MeV

  19. Background: pp ! 2 + 2 − total (pp ) ' 70 mb COMPILATION OF CROSS-SECTIONS 3. p AND anti-p INDUCED REACTIONSBy High-Energy Reactions Analysis Group (V. Flaminio et al.). CERN-HERA-79-03, Oct 1979. 254 pp. 50 b

  20. Capella, Sukhatme, Tan, Tran Thanh VanPhys. Rept. 236(1994)225 Kaidalov, Volkovitsky, Z. Phys. C63(1994)517 Uzhinsky, Galoyan hep-ph/0212369 Shape of BackgroundDual Parton Model (DPM) Kinematic situation favourable → background decreases just below J/ mass 2 days data taking Shape varyingacross J/ signal region Fit by 1st order Chebyshev polynom

  21. Scan of a Resonance R Convolution of resonance width and beam resolution

  22. 6990.88 MeV 6990.92 MeV 6990.84 MeV 6990.96 MeV 6991.00 MeV 6991.04 MeV 6991.08 MeV 6991.12 MeV 6991.16 MeV MC, X(3872) Scan, each 2 days, p/p = 10-5 mode Tagged J/ yield, 2-particle invariant mass / GeV Mass(e+e−) / GeV

  23. X(3872) Excitation Function, MC • Exclusive final statepp → X(3872) • each data point 2 daysdata taking • full background • Preliminary result:fitted width is ~20% larger than input,but (s) still ·100 keV(this would be a syst. erroron the width of X(3872)) • Unfolding (integral equation)is ongoing work(Master Thesis, Univ. Gießen) • Preliminary estimate for Panda¸168 keV for p/p=10−4 Reconstruction efficiency '72% '79 keV X(3872) yield 3.8718 3.8720 3.8722 s / GeV Preliminary stat. errors only

  24. Summary • For the 1st time, MC simulations for X(3872) production at Panda have been performed • Detailed simulation and reconstruction: • final state radiation • vector → vector angular distribution • track finder and track fitter • PID by track and cluster matching • background with dual parton model • Preliminary results are encouraging • Extraction of width is ongoing (integral equation) • For more information about FAIR see Talkby Ulrich Wiedner, Plenary, Friday

  25. Backup

  26. Details of MC Scan • Signal X(3872) Geant3.21 PHOTOS on,angular distribution V ! V PS PS • Background DPM with fast simulation(detector resolution parametrized) • input beam resolution not varyingover scan range • Track finder and track fitterusing TPC and MVDNHits and 2 Cut • Background assumednot varying with s • statistical errors only in fit • yield outside is assumed zero(but hadronic cross section is high)

  27. Resonance Scan Note: the cross section depends on the spin J of the resonance ! a way to determine the quantum number of X(3872) R isindependant from BR x BRbecause it onlyenters into peak

  28. The Pellet Target Here: WASA Target d=25 m fall speed ¸ 60 m/s

  29. MVD (Micro Vertex Detector) • 4 barrels & 8 disks • inner layers pixels • outer layers strips • forward mixed • Silicon Pixel Detectors • 120 modules • 100x100 µm2 pixel size • ~107 readout channels • maximum rate <10 MHits s–1 per module • Radiation length ~1% X0 per layer • Silicon Strip Detectors • 400 modules • ~0.5 m2 active area • 7x104 readout channels dE/dx (a.u.) MVD dE/dx  K pe 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 p/GeV/c

  30. STT (Straw Tube Tracker) • ~4100 tubes, axial or skewed(15 double layers) • R=15.5-41.5 cm • L=1.5m • (only) m=50 kg • tube diameter 10mmwall Mylar, 30μm • anode wire W/Re, 20μm • spatial resolutionσrφ≈150μm (axial layers)σz≈3-10mm (skewed layers) • gas 90%Ar,10%CO2over-pressurefor stabilization p=2 bar • radiation length ~1-1.3% X0 • wire U=2 kV • pT/pT '1.2% • prototype under investigation

  31. TPC (Time Projection Chamber) • R=15.5-41.5 cm • 135 padrows • 135,169 pads of 2x2 mm2 • Multi-GEM for amplification and ion backflow suppression • Gas: Ne/CO2 (+CH4/CF4) • 50-70 µs drift time! 700 events pile-up • gating grid continously open • p/p'1% • prototype under investigation

  32. DIRC(Detection of Internally Reflected Cerenkov Light) 16 Quartz (n=1.47) Bars d=1.7 cm, R=48 cm BaBar design electron0.7 GeV/c

  33. EMC (Electromagnetic Calorimeter) ~17,200 crystals PbWO4 (radiation hard, fast Decay~6 ns) 28 X0 dE/dx=13.0 MeV/cm

  34. EMC (Electromagnetic Calorimeter) operated at T=–25o C E/p

  35. view from GeoManager y z x d=1 cm MUO (Muon Detector) • R = 1.3–1.8 m • tubes (for x coordinate)gold plated tungsten wire, d=0.05 mm, L=4 m, wire U=+3.6 kV, cathode U=-1.2 kV • copper strips (for z coordinate)U=+1.8 kV • ! pad size 1x1 cm2

  36. Resonance Scan Note: the cross section depends on the spin J of the resonance ! a way to determine the quantum number of X(3872) R isindependant from BR x BRbecause it onlyenters into peak

  37. Chen and Ma Estimate Prediction for cross section with X as loosely bound DD* state Chen, Ma, Phys. Rev. D77(2008)097501width X 136 keV - 2.3 MeVcross section 3.57 - 443nb

  38. 1+ vs. 1-

  39. Charmonium Production Cross Section in ppbar Barnes, Li, Phys.Rev.D75:054018,2007. hep-ph/0611340 With one additional meson 5 nb

  40. Dual Parton Model A. Capella, U. Sukhatme, C.-I. Tan, and J. Tran Thanh Van, Phys. Rept. 236, 225 (1994). A. B. Kaidalov and P. E. Volkovitsky, Z. Phys. C63, 517 (1994). [12] V. V. Uzhinsky and A. S. Galoyan, hep-ph/0212369 (2002).

  41.  (2S)! J/+− as reference channel § from X(3872) have higher momentum Reconstruction efficiency is ' 21% higher

  42. Variation of Angular Distributions • With PID Cut • PHOTOS ON (in X decay and J/Psi decay), e+e− only (no Muons) • Negigible effect on reconstruction efficiency (< 1%)! Lorentz boost is dominating angular distribution Phasespace V ! V PS PS

  43. Comparison of e+ e− and +− final states 4-particle invariant mass Radiative Tail in J/ mass generates tail at higher masses in 4-particle invariant mass ' 5 daysdata taking

  44. Resonance Scan Double scan technique Constant Orbit Constant Field(beam energy is changed bystochasticcooling pick-ups)

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