Post on 25-Oct-2021
CiRfSE Workshop2017 / 1 / 24
24th Jan. 17 CiRfSE WS 1
New physics searches in Z + MET events
24th Jan. 17 CiRfSE WS 2
Ex.)
( )
24th Jan. 17 CiRfSE WS 3
: Z + invisible particles
•
•
24th Jan. 17 CiRfSE WS 4
Run-1
Z
O(10)
X
Z + invisible
Z(→ll) + vv(invisible)
ZZ 400 GeV
LHC (~4.2 MeV)
24th Jan. 17 CiRfSE WS 5
Run-1Higgs-portal model (
)
Z
ZH Z + invisible
Invisible particle
invisible particlevisible particle
(ETmiss, MET)
24th Jan. 17 CiRfSE WS 6
( )1. ZZ→llvv2. WZ→lvll3. WW/tt/Z→ττ
4. Z + jets5. W + jets, multi-jets
LHC Z(→ll)+MET
Z
Z
ν
ν
l
Z
24th Jan. 17 CiRfSE WS 7
significance(Z)Z
ATLASwork in progress13 TeV, 3 fb-1
• MET cut• ΔR(l, l)• (PTll – Et
miss, jets)/PTll• φ(Z, ET
miss)• b-tagged jets veto : ttbar• Z PT/MT• Min. Δɸ(jets, ET
miss)
Z+jetsZ ET
miss
High MET
Z =
24th Jan. 17 CiRfSE WS 8
*
ZZ/WZ backgroundZZ
MC
24th Jan. 17 CiRfSE WS 9
PDF uncertainty
QCD uncertainty
WZWZ(3l-CR) +1 lepton
MCScale Factor
SF= 1.25 0.04 (stat) 0.05 (syst)
WW/tt/Z→ττ background
24th Jan. 17 CiRfSE WS 10
→ eμ-CReμ-CR
eμ-CR : Z mass and MET > 90 GeV
MC ε 8%
normalization
Z+jets background
24th Jan. 17 CiRfSE WS 11
ABCD method•Sideband region
•Correlation dΦ(Z, MET)Frac. pt diff.
•
SR
ABCD method
Z+jets background
24th Jan. 17 CiRfSE WS 12
Region B, D Z mass requirement NB/ND
NB/ND
MC ABCD method
MC
60%
MCnormalization
Result ( )
24th Jan. 17 CiRfSE WS 13
Bulk RS graviton mG<1.03 TeV (observed) @ 95 % C.L.
24th Jan. 17 CiRfSE WS 14
Result ( )
ZH98% observed
(65% expected)@95% CL
24th Jan. 17 CiRfSE WS 15
13TeV ATLAS13 /fb Z+invisible particle
ZZ RS-graviton 1.03 TeV
BR(H→inv.) < 98% (obs), 65%(exp) @ 95% CL.
MET
Backup slides
24th Jan. 17 CiRfSE WS 16
Electron channel
22th Jul. 16 HZZ weekly 17
* ZPT reweighting applied
22th Jul. 16 HZZ weekly 18
Electron channelJets > 100 GeV
Jets > 25 GeV
ZPT/MTZZ ZPT/MT
* ZPT reweighting applied
Muon channel
22th Jul. 16 HZZ weekly 19
* ZPT reweighting applied
Muon channel
22th Jul. 16 HZZ weekly 20
Jets > 100 GeV
Jets > 25 GeV
ZPT/MTZZ ZPT/MT
* ZPT reweighting applied
WZ pair productionMeasurement of the WZ boson pair production
cross section in pp collisions at sqrt(s) = 13 TeVwith the ATLAS detector. Phys. Lett. B 762 (2016) 1
lvll channelObserved : 63.2 3.2 (stat.) 2.6 (sys.) 1.5 (lumi) fb
Expected : 53.4 fb
Powheg+Pythia
24th Jan. 17 CiRfSE WS 21
ZZ pair productionMeasurement of the ZZ Production Cross
Section in pp Collisions at √ s = 13 TeV with the ATLAS Detector : arXiv:1512.05314v2 [hep-ex]
24th Jan. 17 CiRfSE WS 22
ABCD method
24th Jan. 17 CiRfSE WS 23
Electron channel Muon channel
: -0.05 (Electron channel) 0.006 (Muon channel)
/
24th Jan. 17 CiRfSE WS 24
ZH98% observed (65% expected)@95% CL
mediator mass,
3l-CR ZZ→llvv
ZZ→llvv MC•
ZZ→llvvZZ→llvv 3l-CR
• WZ ZZ• 3rd lepton MissingET
ZZ→llvv
24th Jan. 17 CiRfSE WS 25
Z/γ*
W+/-
Z
Z/γ*
ν
ν
l
l
l
ν
l
l
MET
ZZ→llvv
WZ→lvll
+ s channel
WZ ZZ
Recomputed mTZZ [GeV] Recomputed ETmiss [GeV]
Even
ts
Even
ts
ZZ/W
Z
ZZ/W
Z
WZ→lvllZZ→llvv
WZ→lvllZZ→llvv
WZ ZZ ZPT→ PTZZ ZPT
24th Jan. 17 CiRfSE WS 26
3l-CR ZZ→llvv
WZ ZZ→llvvCorrection
Normalization~11 /fb
10%
ATLASWork in progress
WZ : 11 /fbZZ→4l : 114 /fb
Recomputed ETmiss [GeV] Recomputed ET
miss [GeV]
Even
tsZZ
/WZ
Recomputed PTZZ [GeV]
Z P T
[GeV
]
Integrated luminosity [/fb]
Unc
erta
inty
[%]
WZ→lvllZZ→llvv
WZ→lvllZZ→llvv
24th Jan. 17 CiRfSE WS 27
RS-graviton
RS graviton mH < 1.03 TeV (observed) @ 95% CL
24th Jan. 17 CiRfSE WS 28
3l-CR ZZ→llvv
Run-1
Run-1 : 75% observed (63% expected) @95% CLRun-2 : 98% observed (65% expected) @95% CL
ZZ
24th Jan. 17 CiRfSE WS 29
CMS
CMS (13 /fb): 86% observed (70% expected) @95% CLATLAS(13 /fb) : 98% observed (65% expected) @95%
CL
24th Jan. 17 CiRfSE WS 30
CMS
24th Jan. 17 CiRfSE WS 31
Period A+B
Period C+D
Period difference
• PeriodC+D
• Period A+B Period C+D
•
Narrow Width Approximation(Width4.07 MeV)
Width ggZZ
limit 4.07MeV
Bulk RS-GravitonRandall-Sundrum Model (RS1)
(k/MPl)= 1
H→ZZ(*)→vvvv
24th Jan. 17 CiRfSE WS 32
Mono-Z searchmediator Simplified
modelmDM, mmed, gq, gDM 4Vector mediator, dirac dark matter, gq =
0.25, gx = 1.0 (Run-1 di-jet)
24th Jan. 17 CiRfSE WS 33
gq gDM
24th Jan. 17 CiRfSE WS 34
LHC
mediatorSimplified model
Z
Mediator ηmDM, mmed, gq, gDM 4 gq gDM