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

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

3  Traditional decay length method to distinguish prompt  Detector resolution limitation  High background from B-decay, maybe difficult since: Current Status of Integral Luminosity 10pb -1 High pt get worse No constrain (0.02)0.02(0.02) (0.01)0.02(0.01) (0.01)0.04(0.01) >150.23(0.02)0.06(0.02)

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

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: Long Distance Matrix Element Probability of the quark pair binding to the quarkonium. Short Distance Coefficient: quark-antiquark pair created. independent of final product. Can be computed by pQCD

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

7  Data sample  CSM &COM,  800K Prompt, 3.7pb -1  370K, 12.8pb -1  Prompt branch ratio Decay Branch ratio Events from 1.3%10.4K 36%224K 20%120K 800K340K Data Samples ~40% prompt events are from decay

8 Expecting Yield trigger rates at a Luminosity = cm -2 s -1 Event SampleRate(Hz) Prompt ( )1.4(0.5) pp  X (include b hadrons decay )1.1 ~10M events pass trigger in the first year. S.QIAN CMS B-physics meeting CERN 28/8/2007

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

10 Sources of Background 1.b hadrons’ decay 2.General QCD, W+jets, Z+jets Sources of Background 1.b hadrons’ decay 2.General QCD, W+jets, Z+jets b-hadrons B0B0 7.1±1<194.3±10.6 B+B+ 8.9±1.4< ±8.6 B0sB0s －－ 50±8.9 BCBC －－ 20±4.1 b-baryon －－ 4.7±2.8 Journal of Physics G: Review of Particle Physics, Vol 33 (2006), page 779 b hadrons’ decay branch ratio

11 Use constrain mass range GeV/c 2 (GeV/c) Signal events No constrain No constrain (0.01)0.02(0.01) (0.01)0.03(0.01) (0.01)0.04(0.01) > (0.01)0.07(0.01) > (0.01)0.09(0.01) >5 0.13(0.01)0.04(0.01) b hadrons to fraction Signal/Background for

12 Use constrain mass range GeV/c 2 Number of photons <3 mass range GeV/c 2 (GeV/c) Signal events No constrain No constrain (0.02)0.02(0.02) (0.01)0.02(0.01) (0.01)0.04(0.01) > (0.02)0.06(0.02) > (0.01)0.04(0.01) b hadrons to fraction Signal/Background for

13 No constrain 0.23(0.02)0.06(0.02) 0.22(0.01)0.07(0.01) b hadrons fraction in High Range >15GeV/c No constrain vs. >15GeV/c No constrain >15GeV/c

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 p T range (p T >15GeV/c).  Future work  Polarization study

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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