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

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 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

Event Selection EF_mu36_tight At least two muons, leading pair same-sign p T > 40 , 15 GeV, preselection p T > 100 , 15 GeV, signal N trk > 20 in signal region Leading Muon is isolated ( ptcone 20 / 20 < 0 . 2) and prompt ( | d sig 0 | < 3) Invert N trk for validation regions B. Heimel 22.2.13 Dimuon Final States 3

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

Background Distributions Events / 16 GeV 2 Events 10 BlackMax BlackMax 2 ttbar 10 ttbar ATLAS Internal ATLAS Internal W+jet W+jet ∫ ∫ Wt Wt -1 -1 Ldt= 10.6 fb Ldt= 10.6 fb WZ WZ ZZ ZZ 10 s = 8 TeV s = 8 TeV 10 1 1 -1 10 -1 10 100 200 300 400 500 600 700 800 10 20 30 40 50 60 Leading Muon p [GeV] N T TRK signal sample: M D = 1 . 5 TeV B. Heimel 22.2.13 Dimuon Final States 5

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 113715 Sherpa singlePhotonPt70 p1181 γ 70 159102 Pythia8 gammajet unbinned70 p1181 top-pair 105861 PowhegPythia ttbar LeptonFilter p1328 single top 108346 MC@NLO Jimmy SingleTopWtChannel Incl p1328 145162 Sherpa lmumugammaPt10 p1328 Z γ 145162 Sherpa lmunugamaPt10 p1328 W γ signal 159237 BlackMaxPythia8 BH2 n=4, M th = 5 TeV p1328 B. Heimel 22.2.13 Dimuon Final States 6

Fake Rate Measurement: Data driven Measure in photon data → apply to µ +trk in data Using EF_g80_loose trigger subtract prompt contamination γ + µ F γ = Z ( µµ ) γ , W ( µν ) γ , W ( µν )+ jets γ + Trk numerator affected by prompts contamination in denominator only ≈ 1 % B. Heimel 22.2.13 Dimuon Final States 7

Uncertainties on Fake Rate Measurement uncertainties (statistics) Background subtraction Photon trigger B. Heimel 22.2.13 Dimuon Final States 8

Applying the Fake Rate Measure fake rate in different p T , η , N trk bins Use fake rate in p T and η bins Use linear fit for N trk Apply to µ ± + trk ± events; predict µ ± + µ ± events F = f ( p T ) · f ( η ) · f ( N trk ) � f � 2 Check prediction vs. observation in validation regions B. Heimel 22.2.13 Dimuon Final States 9

Control Region Summary for Data (A-D) L dt = 10 . 6 fb − 1 � Leading muon N trk Diboson t ¯ Fake Total Wt t p T [GeV] N trk < 10 395.9 294.6 4989 10349 15718 ± 1542 10 ≤ N trk ≤ 11 0.9 5.8 205.0 101.6 313 ± 19 40 < p T < 100 12 ≤ N trk ≤ 14 0.37 4.1 110.0 52.1 167 ± 11 15 ≤ N trk ≤ 19 0.1 1.3 40.7 16.3 58 ± 4 N trk ≥ 20 0.0 0.0 7.5 2.8 10 ± 0.7 N trk < 10 76.2 107.0 1031 1244 2458 ± 185 10 ≤ N trk ≤ 11 1.5 3.0 82.0 34.0 121 ± 7 p T > 100 12 ≤ N trk ≤ 14 0.5 3.1 59.2 17.7 81 ± 4 15 ≤ N trk ≤ 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

Fake Rate in MC 0.03 0.03 Fake Rate Fake Rate W Sherpa W Sherpa W AlpgenJimmy W AlpgenJimmy 0.025 γ 0.025 γ Sherpa Sherpa γ γ Pythia Pythia 0.02 0.02 0.015 0.015 0.01 0.01 0.005 0.005 0 0 20 40 60 80 100 120 140 160 180 200 0 0.5 1 1.5 2 2.5 η p [GeV] T Both γ samples are γ 70 0.35 Fake Rate W Sherpa W AlpgenJimmy 0.3 γ Sherpa F γ = ( γ + µ ) (prompt corrected) γ Pythia 0.25 γ + Trk 0.2 0.15 0.1 W ( µν ) + µ F W = 0.05 W ( µν ) + Trk 0 0 10 20 30 40 50 60 Number of Tracks B. Heimel 22.2.13 Dimuon Final States 11

Fraction of Tracks/Muons from HF in % Sherpa Alpgen Sherpa Pythia Tracks W W γ 70 γ 70 High 11.15 ± 0.09 9.122 ± 0.015 11.66 ± 0.05 12.28 ± 0.07 N trk < 10 11.69 ± 0.09 9.142 ± 0.015 11.68 ± 0.05 12.28 ± 0.07 N trk < 20 11.15 ± 0.09 7.588 ± 0.014 11.66 ± 0.05 12.28 ± 0.07 9 < N trk < 20 8.4 ± 0.9 6.63 ± 0.18 8.2 ± 0.6 4.9 ± 1.6 N trk > 14 4.6 ± 2.1 4.6 ± 0.6 8.4 ± 1.6 0.0004 ± 0.0004 Muons Sherpa Alpgen Sherpa Pythia W W γ 70 γ 70 High 54 ± 2 48.7 ± 0.4 51.4 ± 0.9 72.2 ± 1.7 N trk < 10 55 ± 2 49.2 ± 0.4 51.9 ± 0.9 72.4 ± 1.7 N trk < 20 54 ± 2 48.7 ± 0.4 51.4 ± 0.9 72.2 ± 1.7 9 < N trk < 20 32 ± 9 21.3 ± 1.9 28.8 ± 4 0 ± 0 N trk > 14 25 ± 25 10 ± 3 26 ± 10 0 ± 0 B. Heimel 22.2.13 Dimuon Final States 12

Approximating the Fake Rate with a Linear Fit W Sherpa χ χ 2 2 / ndf / ndf 2.559 / 3 2.559 / 3 0.3 Fake Muon Rate Prob Prob 0.4648 0.4648 ± ± p0 p0 0.003431 0.003431 0.0005925 0.0005925 0.25 ± ± p1 p1 -0.002605 -0.002605 0.00257 0.00257 deviation = measured − extrapolated 0.2 measured 0.15 0.1 value Sherpa % Alpgen % 0.05 12.5 15.5 1.0 0 0 10 20 30 40 50 60 17.5 30.0 17.5 Number of Tracks 40 45.9 27.1 W Alpgen χ χ 2 2 / ndf / ndf 0.8249 / 3 0.8249 / 3 0.3 Fake Muon Rate Prob Prob 0.8435 0.8435 value Sherpa σ Alpgen σ p0 p0 0.002612 0.002612 ± ± 0.0004259 0.0004259 0.25 ± ± p1 p1 -0.001208 -0.001208 0.001878 0.001878 12.5 2.1 0.16 0.2 17.5 1.7 1.0 40 1.4 0.6 0.15 0.1 0.05 0 0 10 20 30 40 50 60 Number of Tracks B. Heimel 22.2.13 Dimuon Final States 13

Closure Test observed p T , η, Trk CR1: 40 < p lead < 100, N trk < 10 T CR1 66 71 CR2: 40 < p lead < 100 , N trk ≥ 10 T CR2 15 13 CR3: p lead > 100, N trk < 10 CR3 25 22 T CR4: p lead > 100, N trk ≥ 10 CR4 16 8 T Table: Alpgen W. observed p T , 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

Conclusion Check different closure test scenarios for Alpgen γ 70 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

Backup Slides

Correlation Tracks W Sherpa γ 70 Pythia γ 70 Sherpa p T vs. η -0.001485 -0.002352 -0.00166 p T vs. NTrack 0.3774 0.137 0.2604 η vs. NTrack -0.0001503 -0.0006818 -0.00361 Table: Correlation in the high case between p T , η and number of tracks W Sherpa γ 70 Pythia γ 70 Sherpa Muons p T vs. η 0.0109 0.008538 -0.0179 p T vs. NTrack 0.03779 0.03296 0.1164 η vs. NTrack -0.001896 -0.01528 -0.01446 Table: Correlation in the high case between p T , η and number of tracks B. Heimel 22.2.13 Dimuon Final States 17

Fit Functions f ( x ) = p 0 · x + p 0 p 0: slope, p 1: y-axis intersection W Sherpa: p 0 = 0 . 003431 ± 0 . 0005925, p 1 = − 0 . 002605 ± 0 . 00257 W Alpgen: p 0 = 0 . 002612 ± 0 . 0004259, p 1 = − 0 . 001280 ± 0 . 001878 B. Heimel 22.2.13 Dimuon Final States 18