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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
Carlo Schiavi on behalf of the Hadronic Decays Group Page 2
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
0.5
MeV
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
Com
bina
tions
per
0.5
MeV
0
500
1000
1500
2000
2500
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
Carlo Schiavi on behalf of the Hadronic Decays Group Page 3
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
Com
bina
tions
per
10
MeV
0
100
200
300
400
500
600
700
800
-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
Com
bina
tions
per
10
MeV
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?
@
Carlo Schiavi on behalf of the Hadronic Decays Group Page 5
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
Carlo Schiavi on behalf of the Hadronic Decays Group Page 7
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
Carlo Schiavi on behalf of the Hadronic Decays Group Page 8
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
Ent
ries
/ 0.5
MeV
0
100
200
300
400
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
Ent
ries
/ 0.5
MeV
0
20
40
60
80
ATLAS
= 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
Ent
ries
/ 0.5
MeV
0
50
100 ATLAS
= 7 TeVs
Preliminary
26±fit: N(D*) = 275 [25,35] GeV (L1_J10, C+D)∈(D*)
Tp
) [MeV]π)-M(KsππM(K140 145 150 155 160
Ent
ries
/ 0.5
MeV
0
10
20
30
40
ATLAS
= 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
Carlo Schiavi on behalf of the Hadronic Decays Group Page 10
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