OBSERVATION STANDARD MODEL HIGGS AND THE CMS LHC€¦ · L. Dodd, U. Wisconsin Feb. 15 2018 1 Ph.D....
Transcript of OBSERVATION STANDARD MODEL HIGGS AND THE CMS LHC€¦ · L. Dodd, U. Wisconsin Feb. 15 2018 1 Ph.D....
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018 1
Laura Margaret Dodd
OBSERVATION OF STANDARD MODEL HIGGS BOSON DECAYS TO TAU LEPTONS AND A SEARCH FOR DARK MATTER WITH
THE CMS DETECTOR AT THE LHC
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
About Me • Laura Margaret Dodd
• B.S. in physics from Duke University
• Worked in ATLAS group
• Entered UW-Madison physics Ph.D. program in 2012
• Advisor: Wesley Smith
• Stationed at CERN between 2014 and 2017
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Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Roadmap
• Motivation and theory
• Experiment and background
• Observation of standard model (SM) Higgs boson to tau pairs
• Search for dark matter (DM) pairs in association with SM Higgs boson in tau pair final state.
• Summary
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Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Standard Model (SM)
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• Fermions (spin-1/2)
• 3 generations of matter
• 6 quarks, and 6 leptons
• 3 charged and 3 neutral leptons
• In SM, neutrinos are massless, unknown extension needed
• Bosons (integer spin) - force mediators
• gluons -> strong force
• γ -> EM force
• W±/Z0 -> Weak force
massless
massless
massive } unified electroweakforce in SM
W±/Z0 sometimes denoted V
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Standard Model (SM): Higgs I
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• Higgs Mechanism
• Scalar doublet is added
• Gauge bosons W±/Z0 acquire mass through spontaneous symmetry breaking and nonzero vacuum expectation
• Massive scalar boson predicted: Higgs boson
• Higgs couples to fermions and therefore fermions gain mass
• 2 main production mechanisms considered:
• gluon fusion (ggH/ggF) and vector boson fusion (VBF)
gluon fusion (ggH)
vector boson fusion (vbf)rate is factor of ten smaller than ggH
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Standard Model (SM): Higgs III
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• In 2012 CMS and ATLAS measured the cross sectional rate of the Higgs coupling to tau leptons and the Higgs coupling to b quarks.
• Signal strength (μ) is defined as observed rate / expected SM rate.
• CMS measured the rate of H→ττ to be μ= 0.88±0.30 times the SM expectation.
• ATLAS measured the rate of H→ττ to be μ=1.41 ±0.40 times the SM expectation
arXiv:1401.6527 [hep-ex]
ATLAS+CMS measure H(bb) μ=0.70 ± 0.29
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Dark Matter
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• Dark matter (DM) exists; the majority of matter in the universe is DM.
• The fundamental nature of DM is not known
• Weakly interacting massive particle (WIMP) may interact with SM through the Higgs sector, as in Higgs-portal models. WIMP DM is denoted χ.
• Ι focus on a collider “mono-Higgs” signature e.g. Higgs+ nothing detected
• Two models examined provide a non-resonant and a resonant handle
2HDM-Z’
baryonic Z’
non-resonant
resonant
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
τ lepton decays
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⌫⌧
e µ d s
W�
⌧�
⌫e ⌫µ u u
1
• Tau lepton heaviest lepton in the SM: 1.77 GeV • Most strongly coupled lepton to Higgs
• Tau lifetime is ~3×10-13 seconds • Taus can decay to hadrons (τh) as well as e,μ
π+ 139 MeV π0 135 MeV
L A R G E H A D R O N C O L L I D E R
OFF ICE
DETECTOR
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Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
LHC• 27 km proton-proton or
heavy-ion collider
• In 2016, operated at 13 TeV center of mass energy
• CMS and ATLAS, general purpose detectors
• ALICE (heavy ion) and LHCb (b-physics)
• Protons accelerated in stages
• Injected into LHC at 450 GeV and accelerated to 6.5 TeV by 400 MHz RF cavities
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Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Cross section and Luminosity
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0.1 1 1010
-7
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σσσσZZ
σσσσWW
σσσσWH
σσσσVBF
MH=125 GeV
HE
LHC
WJS2012
σσσσjet
(ET
jet > 100 GeV)
σσσσjet
(ET
jet > √√√√s/20)
σσσσggH
LHCTevatron
eve
nts
/ s
ec f
or L
= 1
03
3 c
m-2s
-1
σσσσb
σσσσtot
proton - (anti)proton cross sections
σσσσW
σσσσZ
σσσσt
σ
σ
σ
σ
(( ((nb
)) ))
√√√√s (TeV)
{
1 ASU1 0
Dy1 Ju
n1 Ju
O1 AuJ
1 6eS1 2
ct1 1
ov1 D
ec
DDte (87C)
0
10
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30
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7otD
O ,n
teJ
UDte
d L
um
LnoVLt
y (fb−1)
× 50
DDtD included fUom 2010-03-30 11:22 to 2017-08-08 19:00 87C
2010, 7 7eV, 45.0 pb−1
2011, 7 7eV, 6.1 fb−1
2012, 8 7eV, 23.3 fb−1
2015, 13 7eV, 4.2 fb−1
2016, 13 7eV, 40.8 fb−1
2017, 13 7eV, 14.3 fb−1
0
10
20
30
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CMS ,ntegrated LumLnosLty, SS
To increase luminosity: decrease the collision angle (β),
maximize the number of particles per bunch (Νb), and
squeeze each bunch (~𝛜) L =R
�(1)
2016 pp: ~27 interactions/ bunch crossing
C O M PA C T M U O N S O L E N O I D ( C M S )
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Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
CMS Overview
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3.8 T 19.5 kA superconducting
solenoid cooled to 4.7K provides magnetic field to
measure momenta of particles
pTΦ
+z-z
η
θ
p
Hermetic, calorimeters
inside solenoid
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Tracker
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• Silicon tracking system is the first layer within CMS
• Three pixel barrel layers at 4 cm, 7 cm and 10 cm, and two endcap layers extend to |η|<1.5.
• The silicon strips outside the pixel extend coverage up to |η|<2.5
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Electromagnetic Calorimeter
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• Lead tungstate (PbWO4) crystals
• Measures scintillation light
• Extends up to |η| =3
• 26 radiation lengths
• Overall resolution
• Electrons: 0.4% (0.8%) in the barrel (endcaps)
• Photons: roughly ~2%(~4%) in the barrel (endcaps)
density 8.28 g cm-3
radiation length 0.89 cm
molière radius 2.2 cm
interaction length 20.27 cm
light yield ~100 γ /MeV⇣ �
E
⌘2=
✓2.8pE
◆+
0.122
E+ 0.0032 (1)
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Hadronic Calorimeter
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• Extends to |η|<5.2
• Non-ferromagnetic brass absorbers and plastic scintillators for HB/HE
• 16.42 cm nuclear interaction length, and 1.49 cm radiation length
• HB is 12 interaction lengths deep
• HF is steel and quartz fiber Cherenkov-based, 10 interaction lengths deep
HB/HE
HF
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Muon System
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• 1.9 T magnetic field
• Three gaseous chamber technologies until |η|<2.4
• drift tubes (DTs), cathode strip chambers (CSCs), resistive plate chambers (RPCs).
• 10% resolution muons |η|<2.4 and pT<200 GeV muon system only
• Including the tracker measurement improves resolution to less than 2%
|η|<2.4 and pT>200 GeV muon system resolution still ~10%
global fit closer to 5%
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Muon Track-Finder Layer
MPC
CSC DT
LB
RPC
Mezz
Endcap
CuOF
Barrel
Global Muon Trigger
Global Trigger
TwinMux
CPPF
Overlap
ECAL HCAL HB/HE
HCALHF
OSLB
Calo Trigger Layer 1
Calo Trigger Layer 2
Calorimeter Trigger Muon Trigger
CMS Trigger System
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HLT
output rate 100kHz
Save to Diskoutput rate
1kHz
Input beam crossing rate 40MHz
single muon trigger pt>22 or pt>24
single muon + tau
pt(mu) >18 and pt(tau)>20 (tau)>20
single electron pt >25
double hadronic
tauboth pt>35
• Two level trigger system: hardware-based Level-1 and software-based High Level Trigger (HLT)
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Particle Flow
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• Particle Flow (PF) algorithm, used by CMS, links the subsystems together and creates four-vectors for reconstructed physics objects.
• From tracker hits, muon hits, and calorimeter energy deposits, physics “object” four-vectors are created
primary vertex: the collision(vertex) from which our objects are
linked.
PF jets: composed mostly of
charged hadrons, photons, and neutral
hadrons.
pT Transverse Momentum
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Electron/Muon Identification
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• Muons leave tracks in both the tracker and muon system, with no linked calorimeter deposit
• Muon is identified in both the tracker and the muon system
• Muons cut based identification >90% efficient
• Electrons have a track+ ECAL deposit, with no HCAL/Muon deposits
• MVA based identification • signal electrons: 80% efficiency
signal isolation cone charged, neutral ΔR<0.3 (0.4) for electrons (muons)
pileup subtraction term
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Hadronic Tau Identification
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• 55% of tau lepton decays are hadronic τh
• Working point efficiencies and mis-identification probabilities (probability for a jet to fake a tau given loose jet identification requirements)
Eff (%) Mis-idprob (%)
tight 55 8x10-3
med 60 1x10-2
loose 65 2x10-2
anti-e 80 10-3
anti-mu 90 10-3
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Hadronic Tau Reconstruction
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• Hadronic taus are seeded from PF Jets with ΔR=0.4
• Hadron plus strips (HPS) algorithm used to reconstruct hadronic taus
• Dynamic strip reconstruction added in 2015, strip size varies
π0
π+/-π+/- π+/-
π+/-
1-prong 1-prong 1-pi0
3-prongDECAYMODE
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
MET and Jet Identification
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• PF Jets use the Anti-kt algorithm (AK) that clusters the harder particles first, resulting in more circular jets. Default cone size is ΔR=0.4 . They are further corrected with Jet Energy Corrections (JEC).
• Type-1 missing transverse energy (MET) is the negative sum of the transverse momenta of recalibrated jets, and PF objects (e.g. charged hadrons, electrons, and muons).
• Jets are tagged as a b quark jet by identifying possible secondary vertices
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Simulation and Perturbation
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PDF NNPDF 3.0 and NNPDF3.1
Hard scatter POWHEG, MadGraph5+aMC@NLO
Parton Shower Pythia
Hadronization Pythia
Decay Pythia + GEANT
Detector Simulation GEANT
Perturbative expansion of a coupling constant: α<<1
example: perturbative QCD
NLO
1 + α + α2 + α3
Leading order (LO)
Next toLO
(NLO)
Next to NLO
(NNLO)
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Standard Model H→τ τ
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Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Analysis Overview
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• Goals: Measure coupling strength of Higgs boson to tau leptons.
• Target gluon fusion and vector boson fusion productions to measure rate
• Four channels τeτh (denoted eτh) , τμτh (denoted μτh), τhτh, and eμ
• I focus on eτh, μτh, together denoted as ℓτh
• Combined ℓτh make up over 50% of analysis sensitivity
• Two-dimensional signal extraction is used:
• One dimension: invariant mass distribution
• Second dimension: varies on targeted production
gluon fusion (ggH) 13 TeV cross section: 48.58 pb
vector boson fusion (vbf)13 TeV cross section: 3.78 pb
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
ττ Backgrounds
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Drell-Yan Z→ ℓℓ
5700 pbtt → WbWb
830 pb
and inclusive cross section
fake τh
W→ℓν 61000 pb
genuine tau background
mis-reconstructed taubackground
resonantnon-resonant
QCD/multijet~ 1 mb
ℓ=e,μ,τ
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Kinematic Selections
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• Higgs (ττ) final decay products mostly low momentum
• τ→μ and τ→e decay, majority of the τ momentum to go to neutrinos. Expect falling distribution from 15 GeV.
• τ→τh expect falling distribution from 30 GeV.
• Kinematic selections chosen to increase acceptance
• However to reduce fake background, choose pT(τh)>30 in all channels
channel pT
eτhe>26τh>30
μτhμ>20τh>30
τhτhτh>50τh>40
eμ e>13(24) μ>24(15)
η within tracker range excluding eμ
full selection table in thesis
thisthesis
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Mass Reconstruction (mττ)
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• The di-tau mass (mττ) is reconstructed using a kinematic fit in most categories
• Allows for some separation of Z→ττ and H→ττ, and shifts the H→ττ peak to 125 GeV.
• The kinematic fit takes as input: MET, MET uncertainty, each tau candidate’s four vector. It assumes all MET in the event is from neutrinos in tau decay.
given all MET in event comes from tau decay, kinematic fit finds most likely original mass of di-tau system and is
denoted mττ. Visible mass is mvis.
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Background Methods I
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Z->ττ simulation:Madgraph Drell-Yan
Samples.Corrections derived
from highly pure Z →μμ data
sample.
DY ℓ->τ fakes simulation:Madgraph Drell-Yan
Samples.Corrections derived from highly pure Z →μμ data sample. Additional ℓ->τ fake corrections applied.
W+Jets/diboson:Normalization controlled by
data agreement in sideband for
ℓτQCD:
derived from data in sideband region, for ℓτ,
ττ, eμ
TTbar:NLO MC used. Normalization
controlled by data agreement in
sideband for all channels
prefit
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018 31
Background Methods IIℓτ: QCD estimate is taken from same-sign region and
scaled by factor to go to opposite-sign region
sig. reg.
ℓτ: W+Jets estimate is taken from high MT,1
w+jetcontrol region
MT,1
MT,1 =q2p`TE
missT (1� cos(�)) (1)
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we expect no signal in the same-sign region
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Event Selection I
32
MT,1
• Vetoing extra leptons, and requiring well-isolated objects results in the largest decrease in events.
• Next the MT,1<50 GeV cut is applied
Looking for 109.9 events out of 492668 observed
events
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Event Selection II
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• Expect roughly 0.2% of collected events are from gluon fusion and vector boson fusion: 1650 expected signal with 664000 expected background
• Need to increase sensitivity further, define 3 categories: 0jet (targets ggH), boosted (targets ggH), vbf (targets VBF).
0jet no jets with pT>30 GeV
vbf
≥2 jets with pT>30 GeVmjj>300 GeV
pT(ττ)>50 GeV pT(μ)>40 GeV (μτh only)
boosted >0 jets andnot VBF
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Observed Events
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Categorization helps separate ggH and VBF signal. Look at mττ and mvis distributions for shape discrimination
Looking for 29.5 events out of
2927 observed events
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Hττ 2D Categories
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τhτh μτh eτh eμ0jet mττ mvis:τ DM mvis:τ DM mvis : μ pT
boosted mττ : H pT mττ : H pT mττ : H pT mττ : H pT
vbf mττ : mjj mττ : mjj mττ : mjj mττ : mjj
The signal/background increases as a function of total higgs pT (H pT)
The signal/background increases as a
function of leading di-jet invariant mass mjj
has better separation of fakes
in visible mass (mvis) and tau decay mode
(τ DM): next slide
p⌧⌧T = |~pLT + ~pL0
T + ~EmissT |
and 12addl’
sidebands for norm.of bkgs.
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
visible mass: tau decay mode
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0jet: better Z →μμ separation in visible mass
than a kinematic fit
visible mass [GeV]40 60 80 100 120 140 160 180 200
Obs
/Exp
0.60.8
1
1.2
1.4
(13 TeV)-1 2016, 35.9 fbhτµτ
CMSPreliminary
Even
ts
0
5000
10000
15000
20000
25000Observed
ττ→Zµµ→Z
ElectroweakQCDtt
ττ→10xSM H(125)
(13 TeV)-1 2016, 35.9 fbhτµτ
CMSPreliminary
visible mass [GeV]40 60 80 100 120 140 160 180 200
Obs
/Exp
0.60.8
1
1.2
1.4
(13 TeV)-1 2016, 35.9 fbhτµτ
CMSPreliminary
Even
ts
0
5000
10000
15000
20000
25000Observed
ττ→Zµµ→Z
ElectroweakQCDtt
ττ→10xSM H(125)
(13 TeV)-1 2016, 35.9 fbhτµτ
CMSPreliminary
SVfit mass [GeV]40 60 80 100 120 140 160 180 200
Obs
/Exp
0.60.8
1
1.2
1.4
(13 TeV)-1 2016, 35.9 fbhτµτ
CMSPreliminary
Even
ts
0
2000
4000
6000
8000
10000
12000
14000
16000
18000 Observedττ→Zµµ→Z
ElectroweakQCDtt
ττ→10xSM H(125)
(13 TeV)-1 2016, 35.9 fbhτµτ
CMSPreliminary
SVfit mass [GeV]40 60 80 100 120 140 160 180 200
Obs
/Exp
0.60.8
1
1.2
1.4
(13 TeV)-1 2016, 35.9 fbhτµτ
CMSPreliminary
Even
ts
0
2000
4000
6000
8000
10000
12000
14000
16000
18000 Observedττ→Zµµ→Z
ElectroweakQCDtt
ττ→10xSM H(125)
(13 TeV)-1 2016, 35.9 fbhτµτ
CMSPreliminary
ττ μτ eτ eμ
0jet mττ mvis:τ DM mvis:τ DM mττ : μ pT
very few μ->τ fakes in 3 prong, higher S/B
use tau decay mode
mττ
mvis
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
2D Distribution
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“0jet eτ visible mass versus tau decay mode”
1-prong tau visible mass distribution
1-prong-1pi0 tau visible mass distribution
3-prong tau visible mass distribution
mass variable used for
extractionGeV range for mass variablein a bin
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Channel and Category • The SM Higgs excess is seen when sorted by significance of each bin
• VBF is the most sensitive category; μτh eτh are second and third significant channel.
38
channellog(S/(S+B))
3− 2.5− 2− 1.5− 1− 0.5− 0
Even
ts
1−10
1
10
210
310
410
510
610
710
VBF Boosted
0 jet ττ→H
Uncertainty Observed
(13 TeV)-12016, 35.9 fb
CMSPreliminary
log(S/(S+B))1.5− 1− 0.5−
00.20.40.60.8
11.21.41.6 (Data - bkg)/bkg
)/bkgττ→(HBkg. unc.
channel category
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
H(ττ) weighted mass plot • The mass distributions weighted by S/(S+B) show a
visible SM Higgs peak
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Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Energy Scale Uncertainties
40
ν is not included in TES, MET ES
needed.
π- are included in
1.2% Tau ES
νν
τ+
τ-H(125)
π+π+ π-
μ-
ν
μ- have negligible ES
compared with MET, Jet and
Tau ES
Jets in the event affect the MET
measurement. JET ES added to MET
calculation.
Energy Scales (ES) Uncertainty Example: a 50 GeV tau could be +/- 0.4 GeV
jet
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Rate measurement
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• Measured versus expected rates are shown by category and channel
• Measured SM Higgs(ττ) rate is 1.09 +0.27-0.26 of the expected SM rate.
• When shapes are included in the statistic, the observed (expected) significance of the measured H(ττ) decay is 4.9 (4.7) sigma compared to SM expectation without Η(ττ) decay
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
fermionic-vector coupling (κ)• κ, is the ratio of the measured
coupling to the SM expectation.
• The categories separate ggH and VBF for signal production measurements. The measured rate can be broken down as a function of the VBF and ggH process. The vector coupling rate, κV, is compared to the fermionic coupling rate, κf.
• Explicitly, we measure ggH rate at 1.07+0.45-0.41 times the SM expectation, and the VBF rate at 1.06 +0.42-0.41 times the SM expectation.
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Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
[pb]
σPr
oduc
tion
Cro
ss S
ectio
n,
4−10
3−10
2−10
1−10
1
10
210
310
410
510
CMS PreliminaryJuly 2017
All results at: http://cern.ch/go/pNj7W
n jet(s)≥
Z
n jet(s)≥
γW γZ WW WZ ZZµll, l=e,→, Zνl→EW: W
qqWEW qqZ
EWWW→γγ
γqqWEW
ssWW EW
γqqZEW
qqZZEW γWV γγZ γγW tt
=n jet(s)
t-cht tW s-cht γtt tZq ttW ttZ ttttσΔ in exp. HσΔTh.
ggH qqHVBF VH ttH HH
CMS 95%CL limits at 7, 8 and 13 TeV
)-1 5.0 fb≤7 TeV CMS measurement (L )-1 19.6 fb≤8 TeV CMS measurement (L )-1 35.9 fb≤13 TeV CMS measurement (L
Theory prediction
Cross section summary
43
[pb]
σPr
oduc
tion
Cro
ss S
ectio
n,
4−10
3−10
2−10
1−10
1
10
210
310
410
510
CMS PreliminaryJuly 2017
All results at: http://cern.ch/go/pNj7W
n jet(s)≥
Z
n jet(s)≥
γW γZ WW WZ ZZµll, l=e,→, Zνl→EW: W
qqWEW qqZ
EWWW→γγ
γqqWEW
ssWW EW
γqqZEW
qqZZEW γWV γγZ γγW tt
=n jet(s)
t-cht tW s-cht γtt tZq ttW ttZ ttttσΔ in exp. HσΔTh.
ggH qqHVBF VH ttH HH
CMS 95%CL limits at 7, 8 and 13 TeV
)-1 5.0 fb≤7 TeV CMS measurement (L )-1 19.6 fb≤8 TeV CMS measurement (L )-1 35.9 fb≤13 TeV CMS measurement (L
Theory prediction
[pb]
σPr
oduc
tion
Cro
ss S
ectio
n,
4−10
3−10
2−10
1−10
1
10
210
310
410
510
CMS PreliminaryJuly 2017
All results at: http://cern.ch/go/pNj7W
n jet(s)≥
Z
n jet(s)≥
γW γZ WW WZ ZZµll, l=e,→, Zνl→EW: W
qqWEW qqZ
EWWW→γγ
γqqWEW
ssWW EW
γqqZEW
qqZZEW γWV γγZ γγW tt
=n jet(s)
t-cht tW s-cht γtt tZq ttW ttZ ttttσΔ in exp. HσΔTh.
ggH qqHVBF VH ttH HH
CMS 95%CL limits at 7, 8 and 13 TeV
)-1 5.0 fb≤7 TeV CMS measurement (L )-1 19.6 fb≤8 TeV CMS measurement (L )-1 35.9 fb≤13 TeV CMS measurement (L
Theory prediction
VBF measured uncertainty
added to CMS cross section summary plot
H→ττ measured in very good agreement with the SMat a high level of precision! C
ross
Sec
tion σ
(pb)
previous slide:VBF rate at 1.06 +0.42-0.41 times
SM expectation
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Combination with 8 TeV
44
• Conservative combination with the 8 TeV CMS H(ττ) analysis is performed. The observed and expected significance of the H(ττ) decay increases to 5.9 (5.9) sigma as compared with no SM H(ττ).
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018 45
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Mono-Higgs(ττ)
46
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Mono-Higgs Overview
47
• Produce a limit on the number of Higgs bosons (ττ) that decay in association with dark matter.
• use eτh, μτh, τhτh, final states onlysimilar background methods as SM Ηττ3 signal regions (eτh, μτh, τhτh) and 5 control regions for background normalization
• Higgs and MET are roughly back to back, instead of roughly collinear in SM Higgs. The previously used kinematic fit is unusable. Di-boson backgrounds play larger role.
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Mono-Higgs Overview
48
events with b-tagged
jets (60% efficiency WP)
are vetoed
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
μτh 2HDM
Observable: MT,tot
49
• Total transverse mass (MT,tot) used for extraction, signal distributions beyond 260 GeV, background mostly below
(13 TeV)-1 2016, 35.9 fbhτhτ
CMSPreliminary
Total [GeV]TM0 20 40 60 80 100 120 140 160 180 200
Even
ts0
50
100
150
200
250Observed
ττ→Z other→Z
WJetsVV Single TopggH, vbfH, ZHQCDtt
+Jetsνν→Zbkg. uncertainty
(13 TeV)-1 2016, 35.9 fbhτhτ
L.DoddPh.D. ThesisUW-Madison
τhτh
MT,tot [GeV]
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Limit Extraction
50 (GeV)T,totM
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Obs
/Exp
0.5
1
1.5
(13 TeV)-1 2016, 35.9 fbhτeτ
L. DoddPh.D. Thesis
Even
ts
1
10
210
310
410 Observedττ→Z
ll→ZW+jetsMultiboson/Single TopQCD/multijetSM 125 GeV Higgstt
bkg. uncertainty
(13 TeV)-1 2016, 35.9 fbhτeτ
L. DoddPh.D. ThesisUW-Madison
(GeV)T,totM0 200 400 600 800 1000 1200 1400 1600 1800 2000
Obs
/Exp
0.5
1
1.5
(13 TeV)-1 2016, 35.9 fbhτμτ
L. DoddPh.D. Thesis
Even
ts
1
10
210
310
410 Observedττ→Z
ll→ZW+jetsMultiboson/Single TopQCD/multijetSM 125 GeV Higgstt
bkg. uncertainty
(13 TeV)-1 2016, 35.9 fbhτμτ
L. DoddPh.D. ThesisUW-Madison
(GeV)T,totM0 200 400 600 800 1000 1200 1400 1600 1800 2000
Obs
/Exp
0.5
1
1.5
(13 TeV)-1 2016, 35.9 fbhτhτ
L. DoddPh.D. Thesis
Even
ts
1
10
210
310
Observedττ→Z
+jetsνν→ZW+jetsMultiboson/Single TopQCD/multijetSM 125 GeV Higgstt
bkg. uncertainty
(13 TeV)-1 2016, 35.9 fbhτhτ
L. DoddPh.D. ThesisUW-Madison
• Systematics roughly identical to SM Higgs to ττ
• Limited number of simulated events
• Background precision decreases in tails of distribution
• W+jets, WW, and ZZ higher-order correction uncertainties applied, dependent on generated boson pT
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Event Yield
51
background yields in sensitive regiondominated by statistical uncertainties
Can expect up to 5 events in each categoryfor expected Mono-Higgs signal
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Z’-2HDM Model Exclusion
52
[GeV]Z'M600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900
[GeV
]A
M
300
350
400
450
500
550
600
650
1
10
210
310Observed Limit (95% CL)Expected Limit (95% CL)
σExpected Limit +/- 1
(13 TeV)-135.9 fbCMS Preliminary
exclude MZ’ ={700 -1200 GeV} and MA={300-375 GeV}
Mono(ττ) Mono(ττ)+Mono(γγ)
combination of γγ+ττ increases exclusion:
MZ’ ={600 -1350 GeV} and MA={300-400 GeV}
No significant excess compared to
SM expectation
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
(GeV)Z`M10 210 310 410
) (fb
)χχ
H→ B
Z'
→(p
pσ
95%
C.L
.
2−10
1−10
1
10
210 Observed Limitττ+γγ Expected Limitττ+γγ 1 std. dev.ττ+γγ
Observed Limitττ
Observed Limitγγ
Baryonic Z’ Model Exclusion
53
combination of γγ+ττ increases
exclusion range
No significant excess compared to
SM expectation
currentlypreparing for publication
Mono(ττ)+Mono(γγ)
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Summary
54
• SM H(ττ) measurement sees Η(ττ) decay at high-level of precision consistent with prediction
• No significant excess compared to the standard model expectation in dark matter mono-Higgs search
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
END
55
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Backup
56
A thesis is never finished, only abandoned.—Marià Cepeda,
quoting Juan Alcaraz, quoting someone else
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
SMH backup
57
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
P-value and Significance• 125 GeV SM Higgs
• Expected (postfit) significance is 4.7 sigma
• Observed significance is 4.9 sigma
• Obs. p-value ~0.00000006
58
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Visible Tau Energy Scale • Visible Tau Energy Scale
• Includes track and ECAL measurement • Assigned 1.2% Up/Down uncertainty
• TES constrained to small values (0.3%) • Correlate the taus whatever eta/pt/
category • Core of Zττ has taus with pT<70 GeV
highest boost still has mostly low pT taus
• CMS measures tracks well, more final states included than 1.2% measurement.
59
tau decay mode correction
1 prong -1.8%
1 prong 1 pi0 +1%
3 prong +0.4%
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Systematic Uncertainties
60
• Full list included in thesis
• Systematics affecting normalization
• Luminosity measurement
• Trigger efficiencies
• Hadronic tau reconstruction
• Systematics affecting shapes
• Energy Scales (discussed next)
• Drell Yan reweighting to match observed distributions
• W+jet and QCD variation
• Higgs momentum distributions (theory)
• Limited number of events (bin-by-bin)
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
(GeV)vism60 80 100 120
Prob
abilit
y de
nsity
0
0.05
0.1
0.15
0.2
0.25
0.3
13 TeVCMS Simulation Preliminary
)hτµ (0jet, µµ→Z
1 pr
ong
0π
1 pr
ong
+ 3
pron
gs
(GeV)vism60 80 100 120
Prob
abilit
y de
nsity
0.01
0.02
0.03
0.04
0.05
0.06
0.0713 TeVCMS Simulation Preliminary
)hτµ (0jet, ττ→ggH
1 pr
ong
0π
1 pr
ong
+ 3
pron
gs
(GeV)ττm50 100 150 200
(GeV
)jj
m
400
600
800
1000
1200
1400
1600
1800
Prob
abilit
y de
nsity
0
0.01
0.02
0.03
0.04
0.05
13 TeVCMS Simulation Preliminary
)hτµ (VBF, ττ→qqH
(GeV)ττm50 100 150 200
(GeV
)jj
m
400
600
800
1000
1200
1400
1600
1800
Prob
abilit
y de
nsity
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
13 TeVCMS Simulation Preliminary
)hτµ (VBF, ττ→Z
(GeV)ττm50 100 150 200
(GeV
)ττ Tp
0
50
100
150
200
250
300
350
400
Prob
abilit
y de
nsity
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0.018
0.02
0.022
13 TeVCMS Simulation Preliminary
)hτµW+jets (boosted,
(GeV)ττm50 100 150 200
(GeV
)ττ Tp
0
50
100
150
200
250
300
350
400
Prob
abilit
y de
nsity
0
0.005
0.01
0.015
0.02
0.025
0.03
0.03513 TeVCMS Simulation Preliminary
)hτµ (boosted, ττ→ggH
2-Dimensional Distributions
61
0jet boosted vbf
sign
alba
ckgr
ound
sign
alba
ckgr
ound
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018 (GeV)vismU
nder
flow
60-6
565
-70
70-7
575
-80
80-8
585
-90
90-9
595
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rflow
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95-1
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4101 prong 0π1 prong + 3 prongs
Observed µτhτ→Z DY others +jetstt DibosonW+jets QCD multijet 125ττ→H Uncertainty
(13 TeV)-135.9 fbCMS Preliminary , 0 jethτµ
(GeV)vismUnd
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Observed eτhτ→Z DY others +jetstt DibosonW+jets QCD multijet 125ττ→H Uncertainty
(13 TeV)-135.9 fbCMS Preliminary , 0 jethτe
0jet distribution: eτ μτ
62
eτ 0jet: mvis : τ decay mode
μτ 0jet:mvis : τ decay mode
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018 (GeV)ττmU
nder
flow
80-9
090
-100
100-
110
110-
120
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1130
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160
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1−012
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ts/b
in
2−10
1−10
1
10
210
310
410 > 0 GeVττT
p > 100 GeVττT
p > 150 GeVττT
p > 200 GeVττT
p > 250 GeVττT
p > 300 GeVττT
p
Observed µτhτ→Z DY others +jetstt DibosonW+jets QCD multijet 125ττ→H Uncertainty
(13 TeV)-135.9 fbCMS Preliminary , Boostedhτµ
(GeV)ττmUnd
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140-
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rflow
Exp.
(Obs
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1−01
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ts/b
in2−10
1−10
1
10
210
310
410 > 0 GeVττT
p > 100 GeVττT
p > 150 GeVττT
p > 200 GeVττT
p > 250 GeVττT
p > 300 GeVττT
p
Observed eτhτ→Z DY others +jetstt DibosonW+jets QCD multijet 125ττ→H Uncertainty
(13 TeV)-135.9 fbCMS Preliminary , Boostedhτe
boosted distribution: eτ μτ
63
eτ boosted: mττ : H pt
μτ boosted:mττ : H pT
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018 (GeV)ττmU
nder
flow
95-1
15
115-
135
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155
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155
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rflow
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01234
Even
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in
2−10
1−10
1
10
210
310 > 300 GeVjjm > 700 GeVjjm > 1100 GeVjjm > 1500 GeVjjm
Observed µτhτ→Z DY others +jetstt DibosonW+jets QCD multijet 125ττ→H Uncertainty
(13 TeV)-135.9 fbCMS Preliminary , VBFhτµ
(GeV)ττmUnd
erflo
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95-1
15
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155
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ts/b
in2−10
1−10
1
10
210
310 > 300 GeVjjm > 700 GeVjjm > 1100 GeVjjm > 1500 GeVjjm
Observed eτhτ→Z DY others +jetstt DibosonW+jets QCD multijet 125ττ→H Uncertainty
(13 TeV)-135.9 fbCMS Preliminary , VBFhτe
vbf distribution: eτ μτ
64
eτ vbf: mττ : di-jet mass
μτ vbf:mττ : di-jet mass
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
(GeV)Hm110 115 120 125 130 135 140
SMσ/
σ95
% C
L lim
it on
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8Observed Expected
Expectedσ1± Expectedσ2±
Observed Expected
Expectedσ1± Expectedσ2±CMS
)-1Preliminary(35.9 fb
Combined Limit information• We see significant excess
centered near 125 GeV combined asymptotic limits
65
(GeV)Hm110 115 120 125 130 135 140
SMσ/
σ95
% C
L lim
it on
0
0.5
1
1.5
2
2.5
limits_cmb.json:exp0 limits_em.json:exp0
limits_et.json:exp0 limits_mt.json:exp0
limits_tt.json:exp0
limits_cmb.json:exp0 limits_em.json:exp0
limits_et.json:exp0 limits_mt.json:exp0
limits_tt.json:exp0
CMS)-1Preliminary(35.9 fb
• ττ most sensitive channel, followed by μτ
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
W+Jets CR: ℓτ postfit
66
Obs
./Exp
.
0.8
1
1.2
Even
ts/b
in
0
2
4
6
8
10
12310×
Observed eτhτ→Z
DY others +jetsttDiboson W+jets
QCD multijet Unc.
(13 TeV)-12016, 35.9 fb
CMSPreliminary
Obs
./Exp
.
0.8
1
1.2
Even
ts/b
in
0
1
2
3
4
5
6
7
8
9310×
Observed eτhτ→Z
DY others +jetsttDiboson W+jets
QCD multijet Unc.
(13 TeV)-12016, 35.9 fb
CMSPreliminary
Obs
./Exp
.0.8
1
1.2Ev
ents
/bin
02468
10121416182022
310×
Observed µτhτ→Z
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QCD multijet Unc.
(13 TeV)-12016, 35.9 fb
CMSPreliminary
Obs
./Exp
.
0.8
1
1.2
Even
ts/b
in
0
2
4
6
8
10
12
14
16
310×
Observed µτhτ→Z
DY others +jetsttDiboson W+jets
QCD multijet Unc.
(13 TeV)-12016, 35.9 fb
CMSPreliminary
0jet 0jetboosted boosted
eτ μτeτ μτ80 GeV <MT < 200 GeV
signal region is MT<50 GeVMT =q2pTEmiss
T (1� cos(��))
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
(GeV)ττm50 100 150 200
Obs
./Exp
.
0.8
1
1.2
Even
ts/b
in
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
310×
Observed
µτhτ→Z
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QCD multijet
Unc.
(13 TeV)-12016, 35.9 fb
CMSPreliminary
(GeV)vism50 100 150 200
Obs
./Exp
.0.8
1
1.2Ev
ents
/bin
0
2
4
6
8
10
12
14
16310×
Observed
µτhτ→Z
DY others
+jetsttDiboson
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QCD multijet
Unc.
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CMSPreliminary
(GeV)ττm50 100 150 200
Obs
./Exp
.
0.8
1
1.2
Even
ts/b
in
0
100
200
300
400
500
600
700Observed
eτhτ→Z
DY others
+jetsttDiboson
W+jets
QCD multijet
Unc.
(13 TeV)-12016, 35.9 fb
CMSPreliminary
(GeV)vism50 100 150 200
Obs
./Exp
.
0.8
1
1.2
Even
ts/b
in
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
310×
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eτhτ→Z
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QCD multijet
Unc.
(13 TeV)-12016, 35.9 fb
CMSPreliminary
QCD CR: ℓτ postfit
67
0jet 0jetboosted boosted
eτ μτeτ μτAnti-Isolated ℓ Region
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
S/(S+B) Weighted M_VIS Plot
68
(GeV)vism0 20 40 60 80 100 120 140 160 180 200
S/(S
+B) w
eigh
ted
even
ts /
GeV
5
10
15
20
25
30
35
40
ττ→Z
W+jets
QCD multijet
Other bkg.
ττ→H
Uncertainty
Observed
(13 TeV)-12016, 35.9 fb
CMSPreliminary
µ, ehτµ, hτ0 jet: e
(GeV)vism0 50 100 150 200
0.4−
0.3−
0.2−
0.1−
00.10.20.30.4
Data - bkg
ττ→H
Bkg. unc.
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Visible TES treatment
69
tau decay mode correction
1 prong -1.8%
1 prong 1 pi0 +1%
3 prong +0.4%
core of Zττ has taus with pT<70 GeV
highest boost still has mostly low
pT taus
0-jet Boosted: ptH > 300 GeV
τ pt τ pt
τ η
τ η
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Tau eta vs Tau pt per category
70
Boosted:200<ptH<250GeV
Boosted:100<ptH<150GeV Boosted:150<ptH<200GeV
Boosted:250<ptH<300GeV Boosted:ptH>300GeV
0jet
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
0-jet τ Decay Mode 2D
71
• In 0-jet category for ℓτ channels, ZL distribution is mostly confined to 1-prong decay mode and 1-prong 1-pi0. 3 prong is devoid of ZL background.
• Tau ℓ->τ fake scale factors were measured inclusively in pT and hard to extrapolate differentially
• Tau Energy Scale (TES) is better measured when versus by decay mode
(GeV)vism60 80 100 120
Prob
abilit
y de
nsity
0.01
0.02
0.03
0.04
0.05
0.06
0.0713 TeVCMS Simulation Preliminary
)hτµ (0jet, ττ→ggH
1 pr
ong
0π
1 pr
ong
+ 3
pron
gs
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Zee/Zμμ Treatment • The e->τ, μ->τ fakes are further corrected in energy scale (ES) and yield
in eτ and μτ. Versus by decay mode in 0-jet necessitated changes.
• The 1.2% τh ES is not applied to ℓ->τ fakes, the ES measured for ℓ->τ fakes is shown in the table below. Additionally τh anti-lepton discriminator scale factors were measured inclusively, not split by decay mode. Scale factors per decay mode are applied.
72
1-Prong Decay Mode 1-Prong+pi0 3-Prong
μτ τ pt ES -0.2% +/- 1.5% 1.5% +/- 1.5% 0 +/- 1.5%
μ->τ fake rate correction
0.75 (25%) 1.0 (25%) -
eτ τ pt ES 0 +/- 3% 9.5% +/- 3% 0 +/- 3%
e->τ fake rate correction
0.98(12%) 1.2(12%) -
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Full Kinematic Selections
73
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Obs
./Exp
.
0.8
1
1.2
Even
ts/b
in
0
20
40
60
80
100
310×
Observed µτeτ→Z
DY others +jetstt
Diboson W+jets
QCD multijet Unc.
(13 TeV)-12016, 35.9 fb
CMSPreliminary
Other CR: ttbar, ττ QCD postfit
74
• OS, anti-isolated τ, svMass
• 0jet (mττ: 0-300 GeV)
• boosted/vbf (mττ: 0-250 GeV)
Obs
./Exp
.
0.8
1
1.2
Even
ts/b
in
0
0.2
0.4
0.6
0.8
1
1.2
310×
Observed hτhτ→Z
DY others +jetstt
Diboson W+jets
QCD multijet Unc.
(13 TeV)-12016, 35.9 fb
CMSPreliminary
Obs
./Exp
.
0.8
1
1.2Ev
ents
/bin
0
5
10
15
20
25
30
35
40310×
Observed hτhτ→Z
DY others +jetstt
Diboson W+jets
QCD multijet Unc.
(13 TeV)-12016, 35.9 fb
CMSPreliminary
Obs
./Exp
.
0.8
1
1.2
Even
ts/b
in
0
10
20
30
40
50
60
70
310×
Observed hτhτ→Z
DY others +jetstt
Diboson W+jets
QCD multijet Unc.
(13 TeV)-12016, 35.9 fb
CMSPreliminary
QCD ττ Control Regions
0jet vbfboosted
• ttbar control region produced from eμ channel• Affects rate in every
channel/category in fit• Pζ <-35
NOT MY
THESIS
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Hadronic Tau Identification
75
• Working point efficiencies and misidentification probabilities
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Status of 125 GeV Higgs
76
ATLAS and CMS continue Higgs measurements
in Run-II at LHC. ATLAS-CONF-2017-041CMS-PAS-HIG-16-043
• Does the Higgs have a Yukawa coupling? Further confirmation of the yukawa-coupling arrives.
• VH(bb) Run-II evidence at ATLAS with 3.5(3.0) σ observed (expected) with a signal strength µ =1.20 +0.24 -0.23 (stat) +0.34 -0.28 (syst) in 13 TeV. Combination with Run-1: σ observed (expected) 3.6(4.0) with μ = 0.90 ± 0.18(stat.) +0.21 −0.19(syst.)
• H(ττ) Run-II at 4.9(4.7) σ observed (expected) at CMS in 2016 data. (μ=1.06 +0.25 -0.24).
• How can we use it to find dark matter?
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018 (GeV)ττmU
nder
flow
80-9
090
-100
100-
110
110-
120
120-
1130
130-
140
140-
150
150-
160
Ove
rflow
Und
erflo
w80
-90
90-1
0010
0-11
011
0-12
012
0-13
013
0-14
014
0-15
015
0-16
0O
verfl
owU
nder
flow
80-9
090
-100
100-
110
110-
120
120-
1130
130-
140
140-
150
150-
160
Ove
rflow
Und
erflo
w80
-90
90-1
0010
0-11
011
0-12
012
0-11
3013
0-14
014
0-15
015
0-16
0O
verfl
owU
nder
flow
80-9
090
-100
100-
110
110-
120
120-
1130
130-
140
140-
150
150-
160
Ove
rflow
Und
erflo
w80
-90
90-1
0010
0-11
011
0-12
012
0-11
3013
0-14
014
0-15
015
0-16
0O
verfl
ow
Exp.
(Obs
.-Exp
.)
1−0123
Even
ts/b
in
2−10
1−10
1
10
210
310
410 > 0 GeVττT
p > 100 GeVττT
p > 150 GeVττT
p > 200 GeVττT
p > 250 GeVττT
p > 300 GeVττT
p
Observed µτeτ→Z DY others +jetstt DibosonW+jets QCD multijet 125ττ→H Uncertainty
(13 TeV)-135.9 fbCMS Preliminary , Boostedµe
(GeV)ττmUnd
erflo
w40
-60
60-7
070
-80
80-9
090
-100
100-
110
110-
120
120-
130
130-
150
150-
200
Ove
rflow
Und
erflo
w40
-60
60-7
070
-80
80-9
090
-100
100-
110
110-
120
120-
130
130-
150
150-
200
Ove
rflow
Und
erflo
w40
-60
60-7
070
-80
80-9
090
-100
100-
110
110-
120
120-
130
130-
150
150-
200
Ove
rflow
Und
erflo
w40
-60
60-7
070
-80
80-9
090
-100
100-
110
110-
120
120-
130
130-
150
150-
200
Ove
rflow
Exp.
(Obs
.-Exp
.)
1−012
Even
ts/b
in2−10
1−10
1
10
210
310
410 > 0 GeVττT
p > 100 GeVττT
p > 170 GeVττT
p > 300 GeVττT
p
Observed hτhτ→Z DY others +jetstt DibosonW+jets QCD multijet 125ττ→H Uncertainty
(13 TeV)-135.9 fbCMS Preliminary , Boostedhτhτ
boosted postfit: eμ ττ
77
ττ boosted: mττ : Η pT
eμ boosted:mττ : Η pT
NOT MY
THESIS
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018 (GeV)ττmU
nder
flow
95-1
15
115-
135
135-
155
Ove
rflow
Und
erflo
w
95-1
15
115-
135
135-
155
Ove
rflow
Und
erflo
w
95-1
15
115-
135
135-
155
Ove
rflow
Und
erflo
w
95-1
15
115-
135
135-
155
Ove
rflow
Exp.
(Obs
.-Exp
.)
012
Even
ts/b
in
2−10
1−10
1
10
210
310 > 300 GeVjjm > 700 GeVjjm > 1100 GeVjjm > 1500 GeVjjm
Observed µτeτ→Z DY others +jetstt DibosonW+jets QCD multijet 125ττ→H Uncertainty
(13 TeV)-135.9 fbCMS Preliminary , VBFµe
(GeV)ττmUnd
erflo
w40
-60
60-7
070
-80
80-9
090
-100
100-
110
110-
120
120-
130
130-
150
150-
200
Ove
rflow
Und
erflo
w40
-60
60-7
070
-80
80-9
090
-100
100-
110
110-
120
120-
130
130-
150
150-
200
Ove
rflow
Und
erflo
w40
-60
60-7
070
-80
80-9
090
-100
100-
110
110-
120
120-
130
130-
150
150-
200
Ove
rflow
Und
erflo
w40
-60
60-7
070
-80
80-9
090
-100
100-
110
110-
120
120-
130
130-
150
150-
200
Ove
rflow
Exp.
(Obs
.-Exp
.)
1−0123
Even
ts/b
in2−10
1−10
1
10
210 > 0 GeVjjm > 300 GeVjjm > 500 GeVjjm > 800 GeVjjm
Observed hτhτ→Z DY others +jetstt DibosonW+jets QCD multijet 125ττ→H Uncertainty
(13 TeV)-135.9 fbCMS Preliminary , VBFhτhτ
vbf postfit: eμ ττ
78
ττ vbf: mττ : di-jet mass
eμ vbf:mττ : di-jet mass
NOT MY
THESIS
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018 (GeV)vismU
nder
flow
50-5
555
-60
60-6
565
-70
70-7
575
-80
80-8
585
-90
90-9
595
-100
Ove
rflow
Und
erflo
w50
-55
55-6
060
-65
65-7
070
-75
75-8
080
-85
85-9
090
-95
95-1
00O
verfl
owU
nder
flow
50-5
555
-60
60-6
565
-70
70-7
575
-80
80-8
585
-90
90-9
595
-100
Ove
rflow
Exp.
(Obs
.-Exp
.)
02
Even
ts/b
in
2−10
1−10
1
10
210
310
410) > 15 GeVµ(
Tp ) > 25 GeVµ(
Tp ) > 35 GeVµ(
Tp
Observed µτeτ→Z DY others +jetstt DibosonW+jets QCD multijet 125ττ→H Uncertainty
(13 TeV)-135.9 fbCMS Preliminary , 0 jetµe
(GeV)ττm
0 100 200 300
Exp.
(Obs
.-Exp
.)
1−01
Even
ts/b
in
1
10
210
310
410
Observed hτhτ→Z DY others +jetstt DibosonW+jets QCD multijet 125ττ→H Uncertainty
(13 TeV)-135.9 fbCMS Preliminary , 0 jethτhτ
0jet postfit: eμ ττ
79
ττ 0jet: 1-D mττ
eμ 0jet: mvis : μ pT
NOT MY
THESIS
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Combined Impacts
80
302928272625242322212019181716151413121110987654321
θ∆)/0θ-θ(2− 1− 0 1 2
CMS_htt_tt_tt_vbf_13TeV_ZTT_bin_46
CMS_htt_mt_mt_vbf_13TeV_ZTT_bin_8
CMS_eFakeTau_1prong1pizero_13TeV
CMS_eFakeTau_1prong_13TeV
QCDScale_ggH
CMS_eff_trigger_tt_13TeV
CMS_htt_tt_tt_vbf_13TeV_ZTT_bin_43
CMS_htt_mt_mt_0jet_13TeV_W_bin_9
CMS_htt_mt_mt_0jet_13TeV_W_bin_33
CMS_htt_QCD_VBF_tt_13TeV
CMS_htt_et_et_vbf_13TeV_QCD_bin_19
CMS_htt_mt_mt_vbf_13TeV_ZTT_bin_3
CMS_htt_tt_tt_boosted_13TeV_ZTT_bin_32
CMS_scale_t_3prong_13TeV
CMS_htt_tt_tt_boosted_13TeV_ZTT_bin_33
CMS_htt_tt_tt_boosted_13TeV_ZTT_bin_44
CMS_scale_t_1prong_13TeV
CMS_eff_t_13TeV
CMS_htt_tt_tt_vbf_13TeV_QCD_bin_45
lumi_13TeV
CMS_htt_mt_mt_vbf_13TeV_ZTT_bin_13
CMS_htt_QCD_boosted_tt_13TeV
CMS_htt_zmm_norm_extrap_boosted_tt_13TeV
CMS_htt_tt_tt_vbf_13TeV_ZTT_bin_44
CMS_scale_t_1prong1pizero_13TeV
CMS_mFakeTau_1prong_13TeV
CMS_scale_met_clustered_13TeV
CMS_htt_mt_mt_vbf_13TeV_QCD_bin_18
CMS_scale_met_unclustered_13TeV
CMS_scale_gg_13TeV
CMS Internal
r∆0.05− 0 0.05
Pull Impactσ+1 Impactσ-1
• Highest impacts and respective pulls
• Combined all channels and all categories
• Theoretical uncertainty largest impact, unclustered energy scale second largest impact
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Higgs Pt Uncertainty
81
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
pzeta definition
• Variable used to cut for top control region
• measure of MET collinearity with tau candidates
82
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
2D Boosted Category• Moved from svFit total pT to vectorial higgs pT
• Vectorial higgs pT distribution more smooth
• Small impact on expected limit: <2%.
83
p⌧⌧T = |~pLT + ~pL0
T + ~EmissT |
SVHiggspT
VectorialH
iggspT
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
et_vbf_RelativeStatHF0 2 4 6 8 10 12 14 16 18 20
1−10
1
10
210
310 (13 TeV)-135.9 fb
CMSUp 0.008, Down -0.022
W_CMS_scale_j_RelativeStatHF_13TeVUp
W
W_CMS_scale_j_RelativeStatHF_13TeVDown
Factorized JES Treatment • 27 sources of JES in all
categories and channels
• Poorly populated templates in sensitive regions caused impacts to behave poorly.
• JES shape treatment:
• Shapes either kept if variation is smooth, demoted to lnN if “spiky” template, or dropped from the channel and category if negligible.
84
W Template Up and Down “RelativeStatHF”
eτ vbf
example of poorly behaved template with
“spike”
example
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
spread the variationuse lnN
smooth shape“remove spike”
Use LnN
>=1 bin that changes by more than 10%, and total acceptance <2%
for up and down
yes
<10% of bins are different from
nominal template
smooth shapeUse LnN
yes
JES Treatment: Chart
85
up and down histograms are
exactly the same
uncertainty dropped
yes
no>=1 bin that
changes by more than 10%, and total acceptance >2% for up and down
>=1 bin where the relative change in acceptance is five
times the total relative change in
acceptance
no bin where the relative change in acceptance is five
times the total relative change in
acceptance
if if
keep shape
yes
the relative total change in
acceptance is less than 0.5% for the up and for the
down shapes
uncertainty dropped
yes
starthere!!
no no no
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Standard Model (SM): Higgs I
86
scalar doublet
when μ2 < 0 and λ > 0
φ12+φ22=ν
MH2=2λv
v=246 GeV
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
MonoHbackup
87
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Mono-Higgs Outlook
88
• Near future
• Produce more baryonic simulation samples
• Combine with other mono-Higgs decay channels
• Interpret results for DM-nucleon cross section exclusion
• Full Run-II
• Expand analysis to boosted regime where hadronic taus overlap with muon/electron to allow for overlapping tau topology
• Search for heavy scalar (ττ) + DM model
A thesis is never finished, only abandoned.—Marià Cepeda,
quoting Juan Alcaraz, quoting someone else
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
CMS Summary Invisible
89CMS-PAS-HIG-16-009 arXiv:1610.09218 [hep-ex]
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Control Regions
90
(GeV)T,totM0-150 150-325 >325
Obs
/Exp
0.5
1
1.5
(13 TeV)-1 2016, 35.9 fbhτμτ
L. DoddPh.D. Thesis
Even
ts
1
10
210
310
Observedττ→Z
ll→ZW+jetsMultiboson/Single TopQCD/multijetSM 125 GeV Higgstt
bkg. uncertainty
(13 TeV)-1 2016, 35.9 fbhτμτ
L. DoddPh.D. ThesisUW-Madison
(GeV)T,totM0 200 400 600 800 1000 1200 1400 1600 1800 2000
Obs
/Exp
0.5
1
1.5
(13 TeV)-1 2016, 35.9 fbhτμτ
L. DoddPh.D. Thesis
Even
ts
1
10
210
310
410 Observedττ→Z
ll→ZW+jetsMultiboson/Single TopQCD/multijetSM 125 GeV Higgstt
bkg. uncertainty
(13 TeV)-1 2016, 35.9 fbhτμτ
L. DoddPh.D. ThesisUW-Madison
(GeV)T,totM0-150 150-325 >325
Obs
/Exp
0.5
1
1.5
(13 TeV)-1 2016, 35.9 fbhτhτ
L. DoddPh.D. Thesis
Even
ts
1
10
210
Observedττ→Z
+jetsνν→ZW+jetsMultiboson/Single TopQCD/multijetSM 125 GeV Higgstt
bkg. uncertainty
(13 TeV)-1 2016, 35.9 fbhτhτ
L. DoddPh.D. ThesisUW-Madison
(GeV)T,totM0 200 400 600 800 1000 1200 1400 1600 1800 2000
Obs
/Exp
0.5
1
1.5
(13 TeV)-1 2016, 35.9 fbhτeτ
L. DoddPh.D. Thesis
Even
ts
1
10
210
310
Observedττ→Z
ll→ZW+jetsMultiboson/Single TopQCD/multijetSM 125 GeV Higgstt
bkg. uncertainty
(13 TeV)-1 2016, 35.9 fbhτeτ
L. DoddPh.D. ThesisUW-Madison
(GeV)T,totM0-150 150-325 >325
Obs
/Exp
0.5
1
1.5
(13 TeV)-1 2016, 35.9 fbhτeτ
L. DoddPh.D. Thesis
Even
ts
1
10
210
310Observed
ττ→Zll→Z
W+jetsMultiboson/Single TopQCD/multijetSM 125 GeV Higgstt
bkg. uncertainty
(13 TeV)-1 2016, 35.9 fbhτeτ
L. DoddPh.D. ThesisUW-Madison
eτ same signμτ same sign
ττ same-sign
μτ W eτ W
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Mono-Higgs Cutflow
91
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Results II: Combination ττ+γγ
92
(GeV)Z`M10 210 310 410
) (fb
)χχ
H→ B
Z'
→(p
pσ
95%
C.L
.
2−10
1−10
1
10
210 Observed Limitττ+γγ Expected Limitττ+γγ 1 std. dev.ττ+γγ
Observed Limitττ
Observed Limitγγ
(GeV)Z`M310
) (fb
)γγχχ
→ A
H
→(p
pσ
95%
C.L
.
2−10
1−10
1
10
210 Observed Limitττ+γγ Expected Limitττ+γγ 1 std. dev.ττ+γγ
Observed Limitττ
Observed Limitγγ
Z’-2HDM Baryonic-Z’
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Status of 125 GeV Higgs
93
Indirect limit on the branching fraction to Beyond the Standard Model (BSM)
decays, including dark matter (invisible decays)
arXiv:1606.02266 [hep-ex]
• How does SM Higgs boson help with finding dark matter?
• With Run-I combination results, the indirect searches limit the beyond the standard model branching ratio of Higgs to 34%.
• Better H(ττ) and other measurements will help to constrain further.
• We can improve with direct searches.
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Event Yield
94
background yields in sensitive regiondominated by statistical uncertainties
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Experiment backup
95
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Standard Model (SM): Higgs II
96
• Scalar boson discovered by CMS and ATLAS in 2012
• Significance of results driven by ZZ and γγ channels.
• Mass: 125 GeV measured spin-0 scalar
run-II goal: reduce uncertainties!
arXiv:1606.02266 [hep-ex]
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Proton Structure
97
• The LHC collides protons
• Partons (gluons and quarks) interact in collisions
• Gluons, valence quarks (u and d) and sea quarks (virtual q anti-q pairs)
• Parton distribution functions
• Deep inelastic scattering experiments (such as at HERA) provide the probability f(x) for a quark or gluon to have fraction of the protons momentum x
• Without accurate pdfs, no cross section normalization
gluons carry ~50% of proton momenta
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Dynamic strip envelope
98
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Solenoid
99
s
LR
track
3.8 T superconducting solenoid cooled to 4.7K
provides critical magnetic field to
measure momenta of particles
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
LHC Parameters
100
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Radiation lengths
101
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Interaction lengths
102
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Dipole magnetic fields
103
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Bethe-Bloch
104
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018 105
(13 TeV)-1 2016, 36.8 fbhτµτ
CMSPreliminary
visible mass [GeV]0 20 40 60 80 100 120 140
Even
ts
0
10
20
30
40
50
60
70
310×Observed
±h
±
h±: hττ→Zs 0π ±: hττ→Z
±: hττ→Zµµ→Z
ElectroweakQCDtt
(13 TeV)-1 2016, 36.8 fbhτµτ
CMSPreliminary
(13 TeV)-1 2016, 36.8 fbhτµτ
CMSPreliminary
mass [GeV]hτ0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Even
ts
0
20
40
60
80
100
120
310×Observed
±h
±
h±: hττ→Zs 0π ±: hττ→Z
±: hττ→Zµµ→Z
ElectroweakQCDtt
(13 TeV)-1 2016, 36.8 fbhτµτ
CMSPreliminary
Hadronic Tau Reconstruction
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
SM Hττ 8TeV
106
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
SM Higgs TauTau 8 TeV Analysis
107
Straightforward mass-based analysis
Used reconstructed invariant di-Tau mass for signal extraction.
Multi-Variate Analysis(MVA) correction for MET based of the decay modes of each tau.
SVFit
Mass reconstructed using likelihood fit to determine most probable 4 vectors of taus, and met.
Assume all met in event is from taus and need to specify what decay mode of each tau for accurate neutrino estimates
tau decay modes τeτh , τμτh , τhτh , τeτμ , τeτe τμτμ
examined
WH/ZH additionSM H->ττ at 8TeV
CMS-HIG-13-004arXiv:1401.5041 [hep-ex]
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
SM Higgs TauTau 8 TeV Analysis
108SM H->ττ at 8TeV
discriminatingvariables used
CMS-HIG-13-004arXiv:1401.5041 [hep-ex]
• 95% CL limits on SM H→ττ signal strength
• excess on mass spectrum from 115 GeV-135 Gev
and SVfit mass
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
Laura in HEP: summary
109
2012 2013 2014 2015 2016 2017
L1 Trigger MSSM Higgs->hh->ττ bb MSSM Higgs ->ττ SM h->ττ Mono-Higgs ττ
summer summerpreliminary exam
defenseand
find a job
2018
hardware supersymmetry: supersymmetry: thesis: thesis:
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
MSSM Hhh
110
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
SM Higgs as a tool for discovery
111 125 GeV H->ττ used as a tool for searches
• Di-Higgs 2 main flavors
• Measure: SM Trilinear Ηiggs coupling
• Search: New heavy resonance X
• Several di-Higgs bbττ analyses done at CMS
• Non-resonant
• Aims to measure trilinear Ηiggs coupling
• Resonant analysis
• Aims to reconstruct mass peak of “X”
• VH Analysis
• Search for resonant MSSM A->Zh(125)
Hhhττbb
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
bbττ
• Performed at 8 TeV
• 8 TeV Run1 in two different results
• MSSM-driven analysis and Model Independent Analysis
• Performed at 13TeV in 2015 and 2016
• 2016 Analysis has 12.9 /fb
• Resonant and non-resonant production modes
112
plot: CMS-PAS-HIG-16-011
BR h(bb) h(ττ)= 3.6%
125 GeV H->ττ used as a tool for searches
Hhhττbb
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
8 TeV bbττ
113
CMS-HIG-14-034CMS-PAS-HIG-15-013
HHKinFit
Maximum likelihood fit for mass Heavy Higgs, H, using the topology below.
Input: (1) SVfit rebuilds H->ττ first (2) 2 Reconstructed Jets
Di-jet invariant mass constrained to be 125 GeV
125 GeV H->ττ used as a tool for searches
• MSSM Analysis search for Heavy H decays to two 125 GeV h
• Probe low tanβ MSSM
• Model Independent analysis used same techniques and extended the mass range of the search
• Resonant and non-resonant
Hhhττbb
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
8 TeV MSSM H->hh->bbττ
114
CMS-HIG-14-034
• MSSM Analysis search for Heavy H decays to two 125 GeV h
• Kinematic fits assume no other MET in event
• Tau decay Modes: τeτh τμτh τhτh τeτμ
• τμτh most sensitive at low MH- similar to Legacy SM Higgs result.
• τhτh drives limit at high mass.
• Performed in tandem with A->Zh to probe low tanβ MSSM
Hhhττbb
ME: LTAU
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
8 TeV MSSM H->hh->bbττ
115 CMS-HIG-14-034
• A->Zh set stronger limits in MA-tanβ plane
Hhhττbb
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
8 TeV MSSM bbττ+llττ
116
+ =A->Zh H->hh COMB
CMS-HIG-14-034
Hhhττbb
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
MSSM Hττ
117
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
MSSM Higgs TauTau
118
MSSM Higgs Decays to ττ
CMS-PAS-HIG-16-006
• MSSM Ηiggs ττ search with 2.3 /fb in 2015 at 13 TeV
• Gluon-gluon fusion and associated-b production
• 2 categories: one b-tagged jet, no b-tagged jets using medium working point.
• Very similar analysis strategy and event selection to SM Higgs->ττ
• However, single lepton triggers used. No trigger requirement for the tau was applied.
• SVFit is used. The MT,tot variable rebuilt from svFit output performed better than Mττ variable
Ph.D. DefenseL. Dodd, U. Wisconsin Feb. 15 2018
MSSM Higgs TauTau
119
CMS-PAS-HIG-16-006
• Event selection optimized for high mass
• MT,tot used to set limits
• Compared to 8 TeV better high mass limits, but not as sensitive to the low mass as 8 TeV, primarily due to better separation of ttbar backgrounds.
MSSM Higgs Decays to ττ