Hadronic Decays Group Report

Carlo Schiavi on behalf of the Hadronic Decays Group

14 July 2011 (B-physics meeting)

Carlo Schiavi on behalf of the Hadronic Decays Group Page 1

Hadronic Decays Group Report

Outlook

I Cross-section news: D(?)± meson measurements

I Spectroscopy news: prospect of ηc(1S) observation

I Flavour measurement news: b/c ratio in D? samples

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Hadronic Decays Group Report

D?± production cross section: 2.76 TeV resultsL. Gladilin

D!± production at 2.76TeV with MBTS 2

) [GeV]!) - M(Ks!!M = M(K"0.14 0.145 0.15 0.155 0.16 0.165 0.17

Com

bina

tions

per

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0100200300400500600700800900

1000-12.76 TeV DATA, EF_mbMbts_2_NoAlg, 0.605 nb

right charge combinations

wrong charge combinations

72±) = 677 ±fit : N(D*

0.05 MeV± M = 145.57 "

0.05 MeV± M) = 0.47 "(mod#

) (GeV)!) - M(Ks!!M = M(K"0.14 0.145 0.15 0.155 0.16 0.165 0.17

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tions

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30002.76 TeV MC, 108497 & 105001 combined

right charge combinations

wrong charge combinations

114±) = 5981 ±fit : N(D* 0.01 MeV± M = 145.56 "

0.01 MeV± M) = 0.42 "(mod#

kinematic range: pT > 3.0GeV, |!| < 2.1

Acc = 25.6 ± 0.5 %

" = 167± 18 µb (42% of the value at 7TeV)

signal: Gaussmod

backgr: A · (x"m#+)B · expC·(x"m#+)

“D(!)-mesons @ 2.76 and 7 TeV” L. Gladilin 7

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Hadronic Decays Group Report

D± production cross section: 2.76 TeV resultsL. Gladilin

D± production at 2.76TeV with MBTS 2

) [GeV]!!M(K1.6 1.7 1.8 1.9 2 2.1 2.2

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-12.76 TeV DATA, EF_mbMbts_2_NoAlg, 0.605 nb

73±) = 669 ±fit : N(D 1.6 MeV±) = 1870.2 ±M(D

1.6 MeV±(M) = 11.9 mod"

) (GeV)!!M(K1.6 1.7 1.8 1.9 2 2.1 2.2

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tions

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0200400600800

100012001400160018002000

122±) = 5124 ±fit : N(D

0.4 MeV±) = 1870.4 +M(D

0.4 MeV± = 13.8 mod(M)"

2.76 TeV MC, 108497 & 105001 combined

kinematic range: pT > 3.0GeV, |!| < 2.1

Acc = 7.8 ± 0.2 %

" = 156± 17 µb (45% of the value at 7TeV)

signal: Gaussmod

backgr: exp

“D(!)-mesons @ 2.76 and 7 TeV” L. Gladilin 8Carlo Schiavi on behalf of the Hadronic Decays Group Page 4

Hadronic Decays Group Report

D(?)± production cross section: 7 TeV resultsL. Gladilin

!"#$%&'(")*"+*",&*$,-.'/*01 %)2*0 /&"((*(3/4'")(*5'46*789::*%)2*;<=>79?

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Hadronic Decays Group Report

Observation prospects for ηc(1S): first MC testsL. Gladilin, V. Lyubushkin

Our private MC for ηc(1S)

Entries 14

Mean 11.85± -4.861

RMS 8.377± 42.71

Underflow 1

Overflow 0

[MeV] rec-Msim

M

-150 -100 -50 0 50 100 1500

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2Entries 14

Mean 11.85± -4.861

RMS 8.377± 42.71

Underflow 1

Overflow 0

mass resolutionc! • based on PYTHIA MinBias

• use HeavyFlavorHadronFilter to filter outevents with ηc

• ηc → K±π∓K0S via EvtGen

• 319 events with ηc simulated and reconstructed• found 18 events with 4 reconstructed tracks,

those tracks were transported to cascade fitter• cascade fit was successful in 16 events• 14 events pass through loose quality criteria:

(nPIX>0 && nSCT>3) || nSCT>5 for K0S tracks

(nPIX>0 && nSCT>3) for K− and π+

Will now try to observe ηc signal in periods A-B-C of 2010 7 TeV data and measureits production cross section

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Hadronic Decays Group Report

D? flavour ratio: measurement ingredientsA. Coccaro, P. Dondero, A. Ferretto, F. Parodi, L. Rossi, C. Schiavi

We need a tool for b/c fraction measurement in D∗ samples

Many reasons why:

I bb̄ to cc̄ cross section ratio measurement

I systematic error reduction in D?µ measurement

I b-tagging efficiency on charm jets (analysis approved, note in preparation)

Inclusive cross section ratio measurement presented in the past:

I trigger request: minimum bias

I beauty fraction measurement based on D0 pseudo proper time

Most recent news:

I trigger request: added L1 10 trigger

I alternative beauty fraction measurement based on D0 impact parameter

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Hadronic Decays Group Report

D? flavour ratio: trigger selectionA. Coccaro, P. Dondero, A. Ferretto, F. Parodi, L. Rossi, C. Schiavi

Complementing MinimumBias with the addition of other triggers (L1 J10)Study bias vs pT (D∗) (all D∗, D∗ in events which passed L1 J10)

Full acceptance for pT ∼ 25 GeVMinimumBias for pT < 25GeV , L1 J10 otherwise

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Hadronic Decays Group Report

D? flavour ratio: trigger selection, 2010 dataA. Coccaro, P. Dondero, A. Ferretto, F. Parodi, L. Rossi, C. Schiavi

) [MeV]π)-M(KsππM(K140 145 150 155 160

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ries

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ATLAS

= 7 TeVs

Preliminary

70±fit: N(D*) = 608 [6,10] GeV (MinBias, A+B)∈(D*)

Tp

) [MeV]π)-M(KsππM(K140 145 150 155 160

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ries

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= 7 TeVs

Preliminary

28±fit: N(D*) = 185 [10,25] GeV (MinBias, A+B)∈(D*)

Tp

) [MeV]π)-M(KsππM(K140 145 150 155 160

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26±fit: N(D*) = 275 [25,35] GeV (L1_J10, C+D)∈(D*)

Tp

) [MeV]π)-M(KsππM(K140 145 150 155 160

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= 7 TeVs

Preliminary

19±fit: N(D*) = 120 [35,120] GeV (L1_J10, C+D)∈(D*)

Tp

High pT bins: need extension to other L1 JX and L1 EMX items

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Hadronic Decays Group Report

D? flavour ratio: impact parameter fitA. Coccaro, P. Dondero, A. Ferretto, F. Parodi, L. Rossi, C. Schiavi

Results of MC pull tests and real data fits have been already presented for the methodbased on D0 pseudo-proper time

An alternative method has been developed within the same framework, forcross-checks and complementarity, based on D0 impact parameter

The template models:

I model for resolution: Res = Modified Gauss + Gauss

I model for charm: Charm = Res

I model for beauty: Beauty = (Exp + Exp) ⊗ Res

The fit procedure:

I fix resolution model with fit on MC D0 sample

I fix beauty time constants with fit on MC D0 sample

I fit b fraction on sideband-subtracted D∗ candidates data or MC signal

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Hadronic Decays Group Report

D? flavour ratio: impact parameter fit, test on MCA. Coccaro, P. Dondero, A. Ferretto, F. Parodi, L. Rossi, C. Schiavi

Minimum bias trigger → all candidates with pT (D?) > 4.5 GeVTrue MC fraction value: 0.121±0.008 (slightly different selection)

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Hadronic Decays Group Report

D? flavour ratio: impact parameter fit, resolutionJ. Metcalfe, I. Gorelov, S. Seidel, K. Toms

The idea is to get the detector resolution (FD) from K0S → π+π− decays data

Selection and reconstruction of K0S → π+π− candidates:

I vertexing done with VKalVrtFitter

I track cuts: pT > 100 MeV, Npix > 1, Nsct > 6

I candidate cut: pointing angle > 0.999, vertex χ2 < 15

I still working on cleaning up background

Resolution parametrization:

I using a gauss + exp function (same as in CDF study)

FD(d0) = α exp− d20

2σ2 + (1− α) exp− |d0|λ

I instead of fixing all variables in the final charm fraction fit on D? signal, theratio of λ/σ is fixed (same as CDF study)

First results being finalized!

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Hadronic Decays Group Report