TISB 18.05.2001 TISB: Gruppo del Tau 1

TISB18.Maggio.2001

Sesto Fiorentino

Gruppo di lavoro sul :Status report

Gruppo di lavoro sul :Status report

• Giuseppe Bagliesi• Simone Gennai• Giacomo Sguazzoni

TISB 18.05.2001 TISB: Gruppo del Tau 2

MotivationsMotivations

– His an important channel for SUSY Higgs and probably(?) also for light SM Higgs !

– Why is important to select tau hadronic decays?

– We can recover “good part” of signal events

B.R. H->-> ll 12% ->l 35% lh 46% ->hh 65% hh 42%

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Signal events and Bkg samples

Signal events and Bkg samples

• ORCA_4_5_1• Same samples used for LVL3 studies• HI Luminosity (1034 cm-2s-1)

• Benchmark SIGNAL ggbb A/Hbb – MH=200, 500 GeV

• Background samples:– 2 jets samples– most dangerous PT bins:

• 50-80, 80-120, 120-170 GeV

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L1, L2 and L3pxlL1, L2 and L3pxl

• L1 and L2 are calorimetric trigger optimized for tau events– Ref. A. Nikitenko et al. CMS NOTE 2000/055– See talks from A. Nikitenko on this subject

• L3pxl is an isolation criteria based on pixel detector only– Ref. D. Kotlinski CMS IN 2001/017– See talks from Danek on this subject

• L3tk is a new algo developed with the full tracker info in order to improve bkg rejection after L3pxl.

• Final goal is to achieve Bkg rate < 10 Hz with good signal efficiency regardless of Higgs mass value (200, 500 GeV).

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L3pxl L3pxl

~0.

1

~0.05

~0.3

T-jet candidatefrom LVL-2 calo towers

Max PT track (PT>3GeV)

within blue cone

NTK RED CONE = NTK BLACK CONE

LVL3 OK

Only3-layerPIXELs

From the same Pixel PV!!!

PT>1GeV

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A. Nikitenko 07/03/2001 jetmet

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Guardando un solo jet…Guardando un solo jet…

h

L1 Tau(calo)

L2 Tau(calo)

L3pxl Tau (iso)

L3tk Tau

1o jet

2o jet

Cat

ena

di tr

igge

r 1o

jet

Qui sta il nostro

contributo

Questa configurazione

+ L3tk = taglio in PT

Riduzione del fondo

non sufficiente!!!

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Guardando due jet…Guardando due jet…

h

L1 Tau(calo)

L2 Tau(calo)

L3pxl Tau (iso)

1o jet

2o jet

Cat

ena

di tr

igge

r 1o

jet

Cat

ena

di tr

igge

r 2o

jet

Qui

sta

il n

ostr

o co

ntri

buto

L1 Tau(calo)

L3tk Tau

.OR.

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L3tk sul 2o jet: Tracking regionaleL3tk sul 2o jet: Tracking regionale

o=(0,0,0) Z

1st tau jet

PV in p=(0,0,z0)

2nd tau jet:

L1 2nd tau jet candidateReg Tk reconstructs tk in the 2nd jet cone with tk vertex @ (0,0,z0)

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Possible L3tk selections applied to 2nd jet: 1. Isolation criteria similar to L3pxl with full reco Tk (A) 2. Cut on the number of reconstructed Tk in the cone

(B)

– there are still some parameters to be optimised– Very low PT cut is applied at L3Tk (~ 1 GeV)

– Both algorithms have good signal efficiency and achieve the desired bkj rejection

L3tk sul 2o jet: selezione eventiL3tk sul 2o jet: selezione eventi

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L3tk: Isolation in the 2nd jet

mH=200 GeV

Bkg50-80

Bkg80-120

Bkg120-170

# Tk in isolation cone Rs = 0.1 Rm= 0.4

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L3tk: Number of Reco Tk in 2nd jet

mH=200 GeV

Bkg50-80

Bkg80-120

Bkg120-170

# Full Reco Tk (PT>1 GeV)0 < Ntk < 4

Jet cone = 0.4

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Global eff and bkg Rate Global eff and bkg Rate

Signal Eff .

L1 & L2 L3pxl L3tk Global

mH=200 GeV 0,42 0,73 0.70 / 0.83 0.21 / 0.25

mH=500 GeV 0,53 0,74 0.73 / 0.81 0.28 / 0.31

50- 80 GeV 3 x 10-4 0,19 0.38 @ 90% C.L. 2.1 x 10-5

80- 120 GeV 0,01 0,21 0.06 / 0.17 1.6 x 10-4 / 5.4 x 10-4

120- 170 GeV 0,04 0,19 0.07 / 0.14 5.2 x 10-4 / 1.0 x 10-3

Rate after L1,L2,L3 10 / 16 Hz

PRELIMINARY !

Really near to our goal !

1. Isolation criteria of L3pxl with full reco Tk (A)

2. Cut on the number of reconstructed Tk in the cone (B)

Need more statistics !

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SIG Eff vs. QCD RateSIG Eff vs. QCD Rate

0 < PT cut < 40 GeVRs = 0.07 0.08 0.09 0.10

(Isolamento).AND.

(Numero di tracce)

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Concludiamo… Concludiamo…

We have analysed 2nd L1 tau jet in the event reconstructing tracks with regional Tk.

– 2 L3Tk selection criteria studied:• Full Tk isolation of tracks inside the cone (A).• Number of reconstructed tracks in jet cone (B) .

– We achieve to get a Rate of about 10 Hz after all Trigger Levels with a global signal eff 25%

– All cuts are not yet optimised

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To do listTo do list

– Increase statistics to reduce bkg uncertainties.

– Optimise trigger parameters to increase global signal eff.

– Try to combine L3tk criteria to get better performances.

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ExtrasExtras

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L3tk sul 1o jetL3tk sul 1o jet

MH=200GeV

MH=500GeV

Eff vs. Rej (wrt L3pxl) with the full Tk reconstruction:

is really hard to get good signal efficiency and good Bkg rej looking only at 1st jet.

0 < PT cut < 40 GeV