Search for Black Holes at 8 TeV using the ATLAS detector at the LHC - - PowerPoint PPT Presentation

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Search for Black Holes at 8 TeV using the ATLAS detector at the LHC - - PowerPoint PPT Presentation

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Search for Black Holes at 8 TeV using the ATLAS detector at the LHC Bertha Heimel Sourabh Dube, Ryan Heller, Ian Hinchliffe, Dong Won Kim LBNL Friday Meeting February 22nd, 2013 Introduction Exotics: assume extra dimensions LHC can produce

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SLIDE 1

Search for Black Holes at 8 TeV

using the ATLAS detector at the LHC Bertha Heimel Sourabh Dube, Ryan Heller, Ian Hinchliffe, Dong Won Kim

LBNL Friday Meeting

February 22nd, 2013

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SLIDE 2

Introduction

Exotics: assume extra dimensions LHC can produce mini black holes in the √s range Search for black holes in events with large track multiplicity Black holes decay directly in all kinds of SM particles Exotics: assume extra dimensions Using non-isolated and non-prompt muons Similar analysis done with the 2011 Data → published Status talk today Work in progress!

  • B. Heimel

22.2.13 Dimuon Final States 2

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SLIDE 3

Event Selection

EF_mu36_tight At least two muons, leading pair same-sign pT > 40, 15 GeV, preselection pT > 100, 15 GeV, signal Ntrk > 20 in signal region Leading Muon is isolated (ptcone20/20 < 0.2) and prompt (|dsig

0 | < 3)

Invert Ntrk for validation regions

  • B. Heimel

22.2.13 Dimuon Final States 3

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SLIDE 4

Sources of Background

Data driven

W+jets Z+jets, WW+jets single top (s-, t-channel)

from Monte Carlo

t¯ t tW Diboson (WZ, ZZ) Today: present fake rate details

  • B. Heimel

22.2.13 Dimuon Final States 4

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SLIDE 5

Background Distributions

[GeV]

T

Leading Muon p 100 200 300 400 500 600 700 800 Events / 16 GeV

  • 1

10 1 10

2

10

BlackMax ttbar W+jet Wt WZ ZZ

ATLAS Internal

= 8 TeV s

  • 1

Ldt= 10.6 fb

∫

TRK

N 10 20 30 40 50 60 Events

  • 1

10 1 10

2

10

BlackMax ttbar W+jet Wt WZ ZZ

ATLAS Internal

= 8 TeV s

  • 1

Ldt= 10.6 fb

∫ signal sample: MD = 1.5 TeV

  • B. Heimel

22.2.13 Dimuon Final States 5

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SLIDE 6

Monte Carlo Samples

Type DSN Generator Process Comments W 107690 AlpgenJimmy WmunuNp0 p1181 107691 AlpgenJimmy WmunuNp1 p1181 107692 AlpgenJimmy WmunuNp2 p1181 107693 AlpgenJimmy WmunuNp3 p1181 107694 AlpgenJimmy WmunuNp4 p1181 107695 AlpgenJimmy WmunuNp5 p1181 147775 Sherpa Wmunu p1328 γ70 113715 Sherpa singlePhotonPt70 p1181 159102 Pythia8 gammajet unbinned70 p1181 top-pair 105861 PowhegPythia ttbar LeptonFilter p1328 single top 108346 MC@NLO Jimmy SingleTopWtChannel Incl p1328 Zγ 145162 Sherpa lmumugammaPt10 p1328 W γ 145162 Sherpa lmunugamaPt10 p1328 signal 159237 BlackMaxPythia8 BH2 n=4, Mth =5 TeV p1328

  • B. Heimel

22.2.13 Dimuon Final States 6

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SLIDE 7

Fake Rate Measurement: Data driven

Measure in photon data → apply to µ+trk in data Using EF_g80_loose trigger Fγ = γ + µ γ + Trk subtract prompt contamination Z(µµ)γ, W (µν)γ, W (µν)+jets numerator affected by prompts contamination in denominator only ≈ 1%

  • B. Heimel

22.2.13 Dimuon Final States 7

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SLIDE 8

Uncertainties on Fake Rate

Measurement uncertainties (statistics) Background subtraction Photon trigger

  • B. Heimel

22.2.13 Dimuon Final States 8

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SLIDE 9

Applying the Fake Rate

Measure fake rate in different pT, η, Ntrk bins Use fake rate in pT and η bins Use linear fit for Ntrk Apply to µ± + trk± events; predict µ± + µ± events F = f (pT) · f (η) · f (Ntrk) f 2 Check prediction vs. observation in validation regions

  • B. Heimel

22.2.13 Dimuon Final States 9

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SLIDE 10

Control Region Summary for Data (A-D)

  • L dt = 10.6 fb−1

Leading muon Ntrk Diboson Wt t¯ t Fake Total pT [GeV] 40 < pT < 100 Ntrk < 10 395.9 294.6 4989 10349 15718 ± 1542 10 ≤ Ntrk ≤ 11 0.9 5.8 205.0 101.6 313 ± 19 12 ≤ Ntrk ≤ 14 0.37 4.1 110.0 52.1 167 ± 11 15 ≤ Ntrk ≤ 19 0.1 1.3 40.7 16.3 58 ± 4 Ntrk ≥ 20 0.0 0.0 7.5 2.8 10 ± 0.7 pT > 100 Ntrk < 10 76.2 107.0 1031 1244 2458 ± 185 10 ≤ Ntrk ≤ 11 1.5 3.0 82.0 34.0 121 ± 7 12 ≤ Ntrk ≤ 14 0.5 3.1 59.2 17.7 81 ± 4 15 ≤ Ntrk ≤ 19 0.2 2.3 27.9 6.8 37 ± 1.7

Only measurement uncertainty on fake is shown

  • B. Heimel

22.2.13 Dimuon Final States 10

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SLIDE 11

Fake Rate in MC

[GeV]

T

p 20 40 60 80 100 120 140 160 180 200 Fake Rate 0.005 0.01 0.015 0.02 0.025 0.03

W Sherpa W AlpgenJimmy Sherpa γ Pythia γ

η 0.5 1 1.5 2 2.5 Fake Rate 0.005 0.01 0.015 0.02 0.025 0.03

W Sherpa W AlpgenJimmy Sherpa γ Pythia γ

Number of Tracks 10 20 30 40 50 60 Fake Rate 0.05 0.1 0.15 0.2 0.25 0.3 0.35

W Sherpa W AlpgenJimmy Sherpa γ Pythia γ

Both γ samples are γ70 Fγ = (γ + µ)(prompt corrected) γ + Trk FW = W (µν) + µ W (µν) + Trk

  • B. Heimel

22.2.13 Dimuon Final States 11

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SLIDE 12

Fraction of Tracks/Muons from HF in %

Tracks Sherpa Alpgen Sherpa Pythia W W γ70 γ70 High 11.15±0.09 9.122±0.015 11.66±0.05 12.28±0.07 Ntrk <10 11.69±0.09 9.142±0.015 11.68±0.05 12.28±0.07 Ntrk <20 11.15±0.09 7.588±0.014 11.66±0.05 12.28±0.07 9< Ntrk <20 8.4±0.9 6.63±0.18 8.2±0.6 4.9±1.6 Ntrk >14 4.6±2.1 4.6±0.6 8.4±1.6 0.0004±0.0004 Muons Sherpa Alpgen Sherpa Pythia W W γ70 γ70 High 54±2 48.7±0.4 51.4±0.9 72.2±1.7 Ntrk < 10 55±2 49.2±0.4 51.9±0.9 72.4±1.7 Ntrk < 20 54±2 48.7±0.4 51.4±0.9 72.2±1.7 9 < Ntrk < 20 32±9 21.3±1.9 28.8±4 0±0 Ntrk > 14 25±25 10±3 26±10 0±0

  • B. Heimel

22.2.13 Dimuon Final States 12

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SLIDE 13

Approximating the Fake Rate with a Linear Fit

Number of Tracks 10 20 30 40 50 60 Fake Muon Rate 0.05 0.1 0.15 0.2 0.25 0.3 / ndf

2

χ 2.559 / 3 Prob 0.4648 p0 0.0005925 ± 0.003431 p1 0.00257 ±

  • 0.002605

/ ndf

2

χ 2.559 / 3 Prob 0.4648 p0 0.0005925 ± 0.003431 p1 0.00257 ±

  • 0.002605

W Sherpa

Number of Tracks 10 20 30 40 50 60 Fake Muon Rate 0.05 0.1 0.15 0.2 0.25 0.3 / ndf

2

χ 0.8249 / 3 Prob 0.8435 p0 0.0004259 ± 0.002612 p1 0.001878 ±

  • 0.001208

/ ndf

2

χ 0.8249 / 3 Prob 0.8435 p0 0.0004259 ± 0.002612 p1 0.001878 ±

  • 0.001208

W Alpgen

deviation = measured − extrapolated measured value Sherpa % Alpgen % 12.5 15.5 1.0 17.5 30.0 17.5 40 45.9 27.1 value Sherpa σ Alpgen σ 12.5 2.1 0.16 17.5 1.7 1.0 40 1.4 0.6

  • B. Heimel

22.2.13 Dimuon Final States 13

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SLIDE 14

Closure Test

CR1: 40 < plead

T

< 100, Ntrk < 10 CR2: 40 < plead

T

< 100 , Ntrk ≥ 10 CR3: plead

T

> 100, Ntrk < 10 CR4: plead

T

> 100, Ntrk ≥ 10

  • bserved

pT, η, Trk CR1 66 71 CR2 15 13 CR3 25 22 CR4 16 8

Table: Alpgen W.

  • bserved

pT, η, Trk η, Trk CR1 3188 3295 3291 CR2 146 76 142 CR3 888 627 738 CR4 77 45 86.89

Table: Sherpa W.

  • B. Heimel

22.2.13 Dimuon Final States 14

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SLIDE 15

Conclusion

Check different closure test scenarios for Alpgen γ70 sample is buggy Switch to p1328 samples (if available) Test different photon triggers Edboard has been assigned; Documentation in progress Lots of work to be done

  • B. Heimel

22.2.13 Dimuon Final States 15

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SLIDE 16

Backup Slides

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SLIDE 17

Correlation

Tracks W Sherpa γ70 Pythia γ70 Sherpa pT vs. η

  • 0.001485
  • 0.002352
  • 0.00166

pT vs. NTrack 0.3774 0.137 0.2604 η vs. NTrack

  • 0.0001503
  • 0.0006818
  • 0.00361

Table: Correlation in the high case between pT, η and number of tracks

Muons W Sherpa γ70 Pythia γ70 Sherpa pT vs. η 0.0109 0.008538

  • 0.0179

pT vs. NTrack 0.03779 0.03296 0.1164 η vs. NTrack

  • 0.001896
  • 0.01528
  • 0.01446

Table: Correlation in the high case between pT, η and number of tracks

  • B. Heimel

22.2.13 Dimuon Final States 17

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SLIDE 18

Fit Functions

f (x) = p0 · x + p0 p0: slope, p1: y-axis intersection W Sherpa: p0 = 0.003431 ± 0.0005925, p1 = −0.002605 ± 0.00257 W Alpgen: p0 = 0.002612 ± 0.0004259, p1 = −0.001280 ± 0.001878

  • B. Heimel

22.2.13 Dimuon Final States 18