Newphysics searches in Z + MET events

CiRfSE Workshop2017 / 1 / 24

24th Jan. 17 CiRfSE WS 1

New physics searches in Z + MET events


Ex.)

( )


: Z + invisible particles

•

•


Run-1

Z

O(10)

X

Z + invisible

Z(→ll) + vv(invisible)

ZZ 400 GeV

LHC (~4.2 MeV)


Run-1Higgs-portal model (

)

Z

ZH Z + invisible

Invisible particle

invisible particlevisible particle

(ETmiss, MET)


( )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


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 =


*

ZZ/WZ backgroundZZ

MC


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


→ eμ-CReμ-CR

eμ-CR : Z mass and MET > 90 GeV

MC ε 8%

normalization

Z+jets background


ABCD method•Sideband region

•Correlation dΦ(Z, MET)Frac. pt diff.

•

SR

ABCD method

Z+jets background


Region B, D Z mass requirement NB/ND

NB/ND

MC ABCD method

MC

60%

MCnormalization

Result ( )


Bulk RS graviton mG<1.03 TeV (observed) @ 95 % C.L.


Result ( )

ZH98% observed

(65% expected)@95% CL


13TeV ATLAS13 /fb Z+invisible particle

ZZ RS-graviton 1.03 TeV

BR(H→inv.) < 98% (obs), 65%(exp) @ 95% CL.

MET

Backup slides


Electron channel

22th Jul. 16 HZZ weekly 17

* ZPT reweighting applied


Electron channelJets > 100 GeV

Jets > 25 GeV

ZPT/MTZZ ZPT/MT


Muon channel



Muon channel


Jets > 100 GeV

Jets > 25 GeV

ZPT/MTZZ ZPT/MT


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


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]


ABCD method


Electron channel Muon channel

: -0.05 (Electron channel) 0.006 (Muon channel)

/


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


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


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


RS-graviton

RS graviton mH < 1.03 TeV (observed) @ 95% CL


3l-CR ZZ→llvv

Run-1

Run-1 : 75% observed (63% expected) @95% CLRun-2 : 98% observed (65% expected) @95% CL

ZZ


CMS

CMS (13 /fb): 86% observed (70% expected) @95% CLATLAS(13 /fb) : 98% observed (65% expected) @95%

CL


CMS


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


Mono-Z searchmediator Simplified

modelmDM, mmed, gq, gDM 4Vector mediator, dirac dark matter, gq =

0.25, gx = 1.0 (Run-1 di-jet)


gq gDM


LHC

mediatorSimplified model

Z

Mediator ηmDM, mmed, gq, gDM 4 gq gDM

Newphysics searches in Z + MET events

Documents

Transcript of Newphysics searches in Z + MET events