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Experimental Research on Heavy Quarkonium at the CMS: Testing NRQCD with Prompt B-Decay

Explore the results of MC simulations in high-energy physics testing NRQCD and pQCD theories through Heavy Quarkonium. The study focuses on polarization sources like direct and prompt decays, addressing the B-decay puzzle with detectors and resolution improvements. The research aims to distinguish prompt decays using traditional methods and CMS experiments, offering cleaner data with high-pt advantages. Learn about NRQCD production mechanisms, short and long distance coefficients, and polarization probabilities from gluon fragmentation. Utilize signal/background ratios for testing NRQCD at the CMS with event projections and future polarization studies.

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Experimental Research on Heavy Quarkonium at the CMS: Testing NRQCD with Prompt B-Decay

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  1. at the CMS Experimental Research on Bo ZHU School of Physics, Peking University • Motivation • Results of MC • Conclusion

  2. as a Test of NRQCD • Heavy quarkonium for QCD testing • NRQCD and pQCD for CDF quarkonium puzzle • Polarization • sources • Direct • Prompt ( ) (40%) • B-Decay

  3. Current Status of • Traditional decay length method to distinguish prompt • Detector resolution limitation • High background from B-decay , maybe difficult since: Integral Luminosity 10pb-1 High pt get worse

  4. Advantage of • The channel is cleaner • With an additional photon • Small b hadrons decay branch ratio • CMS experiment • (CDF ) • ECAL , MUON system (CDF ) MUONs ECAL

  5. NRQCD: Non-Relativistic QCD • Quarkonium production: • Generate Quark Pair • Quark Pair involves into quarkonium • Non-Relativistic: • Heavy quark moves slowly in heavy quarkonium rest frame . • With CSM and COM: Short Distance Coefficient: quark-antiquark pair created. independent of final product. Can be computed by pQCD Long Distance Matrix Element Probability of the quark pair binding to the quarkonium.

  6. Polarization • polarization: • From fragmenting gluon • 100% transversally polarized • from , Bernd A. Kniehl etc. PHYSICAL REVIEW D, VOLUME 62, 114027

  7. Data Samples • Data sample • CSM&COM, • 800K Prompt , 3.7pb-1 • 370K , 12.8pb-1 • Prompt branch ratio ~40% prompt events are from decay

  8. Expecting Yield trigger rates at a Luminosity = 1032cm-2s-1 S.QIAN CMS B-physics meeting CERN 28/8/2007 ~10M events pass trigger in the first year.

  9. in Generator Level cross section • 38K events normalized to 10pb-1 • Only photon are reconstructed,(28%) • ECAL acceptance: • Angle can be used to decrease background

  10. Sources of Background • Sources of Background • b hadrons’ decay • General QCD, W+jets, Z+jets • Sources of Background • b hadrons’ decay • General QCD, W+jets, Z+jets • b hadrons’ decay branch ratio Journal of Physics G: Review of Particle Physics, Vol 33 (2006), page 779

  11. Signal/Background for • Use constrain • mass range 2.9-3.3GeV/c2 • b hadrons to fraction

  12. Signal/Background for • Use constrain • mass range 2.9-3.3GeV/c2 • Number of photons <3 • mass range 3.3-3.7GeV/c2 • b hadrons to fraction

  13. vs. in High Range >15GeV/c >15GeV/c No constrain • b hadrons fraction >15GeV/c >15GeV/c No constrain

  14. Summary • can be used on CMS to test NRQCD • There will be about 10M event pass CMS trigger in the first year • With the constrain of number of photon and , the signal of prompt is about 15 times of the number of B-decay background in high pT range (pT>15GeV/c). • Future work • Polarization study

  15. END Thank you!

  16. backup

  17. Fraction 0.21

  18. Number of photon In prompt chi_cj event Mean= Number of photon In B to J/Psi event Number of photon In prompt J/Psi event

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