Impact parameter studies in jet events
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Impact parameter studies in μ+jet events. Data: p1014 and p1015 “mujets” files from Markus Klute for the top group (up to March 24) also use new trackfit µ+jet files from Suyong Choi and Onne Peters MC: 6000 Z  bb (p1015) 7000 cc inclusive (Pt>10, p100801)

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Impact parameter studies in μ+jet events

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Impact parameter studies in jet events

Impact parameter studies in μ+jet events

  • Data: p1014 and p1015 “mujets” files from Markus Klute for the top group (up to March 24)

  • also use new trackfit µ+jet files from Suyong Choi and Onne Peters

  • MC: 6000 Zbb (p1015)

  • 7000 cc inclusive (Pt>10, p100801)

  • 9000 qcd (Pt>10, p100801)

  • + 5000 qcd (Pt>20, p1015)

Daniel Bloch + D.Gelé, S.Greder, I. Ripp-Baudot (IReS Strasbourg)

(gives uds,g)

D. Bloch (IReS Strasbourg)


Selection criteria

Selection criteria

  • At least one JCCB jet (standard cuts)

  • Primary vertex PVSEL with  3 tracks and -0.15<XPV<0.15 cm , -0.20<YPV<0.20 cm

  • For the data (not for the MC, due to the lack of statistics …) : 1 global muon with nseg  3, Pt  4 GeV / beam, dR<0.5 from jet axis

  • Use secondary vertices from SKRECO

  • Data tracks with SMT only (except new trackfit), MC tracks with SMT+CFT

D. Bloch (IReS Strasbourg)


Muon pt jet muon axis ptrel

muon pt / (jet+muon) axis (ptrel)

b efficiency=3%

c eff=0.2%

(GeV)

Data 30000 events

light

D. Bloch (IReS Strasbourg)


Decay length in data and mc

Decay length in data and MC

b 48%

c 9%

Probability to find a secondary vertex in jet

(cm)

light 4%

Data 3%

D. Bloch (IReS Strasbourg)


Decay length significance

Decay length significance

b

c

light

Data

D. Bloch (IReS Strasbourg)


Invariant mass at secondary vertices

Invariant mass at secondary vertices

b

c

Mass of all tracks at secondary vertices in the same jet

(GeV)

light

Data

D. Bloch (IReS Strasbourg)


Impact parameter significance

Impact parameter significance

Use only tracks with Pt  0.5 GeV and dca  1 mm

b

c

Sign the dca using the PV-perigee and jet directions

light

Data

D. Bloch (IReS Strasbourg)


Impact parameter significance in data

Impact parameter significance in Data

all tracks

D. Bloch (IReS Strasbourg)


Impact parameter significance in data1

Impact parameter significance in Data

tracks from primary vertex are removed

D. Bloch (IReS Strasbourg)


Impact parameter significance in data2

Impact parameter significance in Data

on μ side opposite side (Δφ90°)

ptrel<0.5 GeV

red: positive tail yellow: negative tail

0.5<ptrel<1

1<ptrel<3

D. Bloch (IReS Strasbourg)


Removing tracks from primary vertex

removing tracks from primary vertex

on μ side opposite side

ptrel<0.5

0.5<ptrel<1

1<ptrel<3

D. Bloch (IReS Strasbourg)


New track fit sample dca

New track fit sample : dca

SMT alone or SMT+ 7 CFT hits : σ = 60 µm

SMT and 7 CFT hits : σ = 50 µm

(cm)

SMT only : σ = 100 µm

all “old” p1014+p1015 µ+jet data : σ = 100 µm

D. Bloch (IReS Strasbourg)


New track fit dca error wrong error

New track fit : dca/error (wrong error ?)

SMT alone or SMT+ 7 CFT hits : σ =1.8

SMT and 7 CFT hits : σ =1.6

SMT only : σ =2.5

all “old” p1014+p1015 µ+jet data : σ =2.6

D. Bloch (IReS Strasbourg)


Summary

Summary

Clear flight distance from b decay in muon+jet events (both on muon side and in opposite jet)

Less easy to use other kinematic variables to tag b-decays

(maybe mass at secondary vertex ?)

D. Bloch (IReS Strasbourg)


Invariant mass at secondary vertices1

Invariant mass at secondary vertices

b

c

zoom at low mass

(GeV)

light

Data

D. Bloch (IReS Strasbourg)


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