IHEP and IPNL Cooperation
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IHEP and IPNL Cooperation
Guoming Chen, IHEP CAS
Suzanne Gascon-Shotkin, IPNL/UCB Lyon 1
on behalf of
IHEP Beijing &IPN Lyon
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The CMS group at IPN Lyon: 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)
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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.
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• 3 of the permanent physicists and 2 students of the group have participated in study preparation for the Physics TDR (PTDR).
• 4 of the permanent physicists and 4 students of the group are currently working on the preparation for CMS physics analysis
Man power in analysis
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IPNL Contributions to the CMS Physics TDR: Higgs physics
Exclusive W(Z)H/ttH, HExclusive W(Z)H/ttH, H22JPhys.G34:N105-N132,CMS AN206/064
tth, h->tth, h->
Wh, h->Wh, h->
Irreducible Irreducible ttttWW4j 4j backgrounds backgrounds added to added to ALPGEN ALPGEN
Unlikely to be Unlikely to be discovery channels discovery channels alone (except in alone (except in MSSM MSSM interpretation) but interpretation) but could be added to could be added to other channels to other channels to boost visibility.boost visibility.
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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
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Physics of Heavy Ions
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) →
CMS: good acceptance:
1% for J/, 25% for l’ good mass resolution:
~35 MeV @ J/ et 90 MeV@
High-Density QCD with HI, PTDR Addendum
5 march 2007
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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
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CMS IHEP ActivitiesHardware :
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
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IHEP Contribution to CMS PTDR
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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)
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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
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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
0
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Photon energy scale and efficiency using Z studies
J. TAOJ. TAOIHEP-Beijing/IPN LyonIHEP-Beijing/IPN Lyon
C. BATY, N. CHANON, S. GASCON-C. BATY, N. CHANON, S. GASCON-SHOTKIN, M. LETHUILLIERSHOTKIN, M. LETHUILLIER
IPN Lyon/ Université Claude Bernard IPN Lyon/ Université Claude Bernard Lyon ILyon I
O. ATRAMENTOV, Y. GERSHTEINO. ATRAMENTOV, Y. GERSHTEIN
Florida State UniversityFlorida State University
Y. MARAVINY. MARAVIN
Kansas State UniversityKansas State University
CMS e/gamma Photon Object workshop CMS e/gamma Photon Object workshop
Sept 25, 2007Sept 25, 2007
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Precision EW measurements/search for anomalous Precision EW measurements/search for anomalous
couplingscouplings
Z + Z + , , ZZA clean source of A clean source of
photons, can determine, with real data: photons, can determine, with real data:
• Efficiency of photon triggers Efficiency of photon triggers
• Determination of photon energy scale Determination of photon energy scale
• Determination of photon id efficiencyDetermination of photon id efficiency
• Determination of photon energy correctionsDetermination of photon energy corrections
General Interest of Z + , Zll « Inner Brem »
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Z + Signal: Matrix Element Generators ALPGEN and CompHEP
CompHEP (CompHEP (Boos, Dubinin, Ilyin, Savrin et al.)Boos, Dubinin, Ilyin, Savrin et al.) and ALPGEN ( and ALPGEN (Mangano, Mangano, M.Moretti, Piccinini, Pittau, PolosaM.Moretti, Piccinini, Pittau, Polosa): Both LO ME generators (new ): Both LO ME generators (new pp process in ALPGEN mid-2007) , photon as part of hard event process in ALPGEN mid-2007) , photon as part of hard event
Both include ISR and FSR diagrams in the hard eventBoth include ISR and FSR diagrams in the hard event
ALPGEN in addition permits extra jets in the hard event with ME/PS ALPGEN in addition permits extra jets in the hard event with ME/PS matchingmatching
FSRFSR
ISRISR
DYDY
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CompHEP-ALPGEN comparisons at particle level
Mostly good agreement between ALPGEN and CompHEP kinematical Mostly good agreement between ALPGEN and CompHEP kinematical Distributions …Distributions …
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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
COMPHEP Gen Y. Gershtein, AN 2005/040
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:
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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.
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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.
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A significant background to H→γγ process
originates from π0’s in jets, which fake single
isolated photons.
Discrimination of γ/π0 using Neutral Network is
not very promising.
γ/π0 Separation: Motivation
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Nominal shower shape of π0 ( in fact 2γ)
Shape of 2 γ EM showers
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!
Possible solution: Method used in L3
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The TB2006 data can be well fitted
by the empirical formula, especially
in 3×3 crystal array (above the
green line).
Progress: First step is done
4
2
)(
6)(
Rr
rRrf
(x,y,z)
plane S[i]
ΔS[i]
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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