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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