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IHEP and IPNL Cooperation

IHEP and IPNL Cooperation. Guoming Chen, IHEP CAS Suzanne Gascon-Shotkin, IPNL/UCB Lyon 1 on behalf of IHEP Beijing &IPN Lyon. The CMS group at IPN Lyon: Overview. Current composition of the group: 1 1 permanent physic ists: 4 Research Directors

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IHEP and IPNL Cooperation

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  1. IHEP and IPNL Cooperation Guoming Chen, IHEP CAS Suzanne Gascon-Shotkin, IPNL/UCB Lyon 1 on behalf of IHEP Beijing &IPN Lyon

  2. The CMS group at IPNLyon: Overview • Current composition of the group: • 11 permanent physicists: • 4 Research Directors • (M. Bedjidian (Heavy Ions), D.Contardo, J. Fay, B. Ille [Laboratory Director]) • 3 Professors • (P. Depasse, H. El Mamouni, S. Gascon-Shotkin), • 2 Research Scientists • (R. Chierici, M. Lethuillier), • 1 Junior Research Scientist (G. Boudoul), • 1 Junior Professor (S. Perriès ) • 4 Doctoral Students (E. Chabert, C. Baty, Th. LeGrand, N. Chanon) and 1 Visiting Doctoral Student (J. Blaha)

  3. The group has made and is making very significant contributions to the R&D, construction, test beams and installation of portions of the CMS ECAL and TRACKER Assembly and calibration of all ECAL photodetection devices, testing of FE amplifier ASICS, calibration of all ECAL FE electronic readout cards, characterisation of tracker detector modules, creation of the tracker construction database, Assembly of a tracker endcap. Key roles in ECAL testbeam analysis. • The group is currently focussing on contributing to CMS commissioning and early physics.

  4. Man power in analysis • 3 of the permanent physicists and 2 students of the group have participated in study preparationfor the Physics TDR (PTDR). • 4 of the permanent physicists and 4 students of the groupare currently working on thepreparation for CMS physics analysis

  5. Wh, h->gg tth, h->gg IPNL Contributions to the CMS Physics TDR: Higgs physics Exclusive W(Z)H/ttH, H2g JPhys.G34:N105-N132,CMS AN206/064 Irreducible ttgg, Wgg4j backgrounds added to ALPGEN Unlikely to be discovery channels alone (except in MSSM interpretation) but could be added to other channels to boost visibility.

  6. Physics of the Standard Model: Physics of Top Quarks Very early (0,3 fb-1) b-tag-less t mass measurement n Semi-leptonic ttbar events

  7. Physics of Heavy Ions High-Density QCD with HI, PTDR Addendum 5 march 2007 • Physics process: Formation of quark-gluon plasma in PbPb collisions and observation of resonance suppression (central collisions instead of peripheriques) • Goal: mesure quarkonia production (q - anti-q) →m+m- • CMS: good acceptance: 1% for J/, 25% for l’ good mass resolution: ~35 MeV @ J/ et 90 MeV@ 

  8. The CMS group at IHEP Beijing: Overview • Current composition of the group: • 8 permanent physicists: • 1 Research Directors • H.S. Chen • 2 Professors • G.M. Chen, C.H. Jiang • 2 Associated Professors • M. Yang, J.G. Bian • 3 Research Scientists • X.W. Meng, Z. Wang, Z.H. Li • 6 Doctoral Students • J.Q. Tao, Z. Zhang, J. Wang, M.S. Chen, Z.C. Tang, J.J. Zang

  9. CMS IHEP Activities • Hardware : The group has built one third of the MUON endcap chambers. Now involved in commissioning • Analysis : 1 permanent and 2 students involved PTDR; Currently 4 permanents and 5 students involved in physics analysis

  10. IHEP Contribution to CMS PTDR

  11. IHEP Current Analysis Activities • Higgs search through H→ZZ→μμνν • HWW anomalous coupling measurement • V’ →ZW →μμμν search • Inclusive b →J/ψ →μμ production • B+ →J/ψ K+ production • Higgs search through H→ττ (with PKU) • Z’ →μμ search (with FU)

  12. History of the Cooperation • January 2006: Agreement to explore possible collaboration on CMS physics analysis after visit of F. LeDiberder to IHEP • July 2006: First visit of IPNL physicists and Director Bernard Ille to IHEP • December 2006: Participation and contribution of both teams to organisation of 1st France-China Workshop on LHC physics and Grid computing at IHEP (ancestor of the FCPPL Workshop) • January-May 2007 IHEP Ph.D student Tao Junquan at IPNL (IN2P3) • May 2007: PICS proposal (CNRS Programme for International Scientific Collaboration) for collaboration funding for 2008-2010 received IN2P3 support • November 2007-April 2008 IHEP Ph.D student Zhang Zhen at IPNL (FCPPL 2007) • January 2008: Participation and contribution of both teams to organisation of this workshop

  13. p0 IHEP/IPNL cooperation on CMS analysis Physics Channel: H→ Topics: 1. Using Z→ to calibrate high energy  Initialized by IPNL 2. π0/ separation Initialized by IHEP

  14. Photon energy scale and efficiency using Z studies J. TAO IHEP-Beijing/IPN Lyon C. BATY, N. CHANON, S. GASCON-SHOTKIN, M. LETHUILLIER IPN Lyon/ Université Claude Bernard Lyon I O. ATRAMENTOV, Y. GERSHTEIN Florida State University Y. MARAVIN Kansas State University CMS e/gamma Photon Object workshop Sept 25, 2007

  15. General Interest of Z + g, Zll « Inner Brem » • Precision EW measurements/search for anomalous • couplings • Z + g, Zmm : A clean source of • photons, can determine, with real data: • Efficiency of photon triggers • Determination of photon energy scale • Determination of photon id efficiency • Determination of photon energy corrections

  16. Z + gSignal: Matrix Element Generators ALPGEN and CompHEP • CompHEP (Boos, Dubinin, Ilyin, Savrin et al.) and ALPGEN (Mangano, M.Moretti, Piccinini, Pittau, Polosa): Both LO ME generators (new pp process in ALPGEN mid-2007) , photon as part of hard event • Both include ISR and FSR diagrams in the hard event • ALPGEN in addition permits extra jets in the hard event with ME/PS matching DY ISR FSR

  17. CompHEP-ALPGEN comparisons at particle level Mostly good agreement between ALPGEN and CompHEP kinematical Distributions …

  18. COMPHEP Gen  Y. Gershtein, AN 2005/040 Backgrounds • Considered for PTDRI: Z+jets (PYTHIA) • Z+jets: + fake  from jets: mostly real Z; no  correlation • Z(+jets):  + fake  from muon passage through ECAL: mostly real Z;  extrapolation to ECAL will coincide with photon position • Not considered for PTDRI: • γ + njets (light): few muons and non-Z • But enormous cross-sections • bb: + from b’s: non-isolated muons; •  anti-correlate (g-splitting) • jbb: fake + from b’s:

  19. What accomplished • Z signal events (1_3_1) have been produced with ALPGEN and CompHEP, and compared at the particle and reconstruction levels. (cross section, kinematic distributions …) Mostly understood • Signal event yields and fitting tools have been validated.

  20. What in progress • Re-production of ALPGEN signal events in 1_4_6/1_6_0 to be able to determine trigger efficiencies • Finish pre-studies to decide « final » generator-level cuts on Et_gamma and DR (,g) and zones of validity for PYTHIA and ME photon generation (in collaboration with ALPGEN authors) • Refine selection for identification of reconstruction-level  • Selection at reconstruction level, including both  signal and background events. Update estimates of background event yields. • Exploitation of developed tools to establish precision of extracted energy scale, id. efficiencies and corrections (with more statistics) as a function of acquired integrated luminosity.

  21. γ/π0Separation: Motivation • A significant background to H→γγ process originates from π0’s in jets, which fake single isolated photons. • Discrimination of γ/π0using Neutral Network is not very promising.

  22. Nominal shower shape of π0 ( in fact 2γ) Shape of 2 γEM showers Possible solution: Method used in L3 • Parameterize the electromagnetic shower shape by a formula. • Fit a shower ( maybe the nominal shower shape of π0 or not) by the parameterized formula, and fit with 2 EM shower, then compare the fitting χ2. • If better fitting result with 2 EM showers, then calculate the invariant mass of the 2 EM showers. • If the invariant mass locates at π0 peak, then the shower is π0. • Else it is γ!

  23. Progress: First step is done ΔS[i] (x,y,z) plane S[i] • The TB2006 data can be well fitted by the empirical formula, especially in 3×3 crystal array (above the green line).

  24. Conclusion and future plans • Good progress in H→γγ through our cooperation • To finish the on going  and γ/π0 separation studies • To apply the obtained results to H→γγ search

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