The Lonesome Higgs
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Richard Kass
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The Ohio State University
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Second level
Outline
ThirdIntroduction
level
to Higgs
LHC
and ATLAS
Fourth
level
Finding the first Higgs particle
Fifth level
Finding the next Higgs particle
Summary
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What is a “Higgs”
A person
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• Click to edit Master text styles
• Second levelPeter Higgs
Professor Emeritus, University of Edinburgh
• Thesis:
Third“Some
level
PhD
problems in the theory of molecular vibrations”
Awards: Nobel Prize, Wolf Prize, Sakurai Prize, Dirac Medal,+++
• Fourth level
A mechanism
A way
to eliminate
• Fifth
levelzero mass scalar particles and give mass to vector
bosons in a theory with a spontaneously broken continuous symmetry.
A field
Its vacuum expectation value is responsible for giving mass to vector
bosons, quarks, & charged leptons.
A particle
(aka “God particle”)
A particle with mass ~125X that of a proton.
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2
What are the quantum numbers
of
a
Higgs
particle?
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The angular momentum (spin) of a Higgs particle is 0
The parity (P) of the lightest Higgs particle is +
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The• parity
a particle
is determined
by how its
wavefunction transforms under (x,y,z) -> (-x,-y,-z)
• Second level
P Ψ(x,y,z)= Ψ(-x,-y,-z)=+Ψ(x,y,z) for + parity (e.g. Ψ(x,y,z)=x2+y2+z2 )
P Ψ(x,y,z)=
for – parity (e.g. Ψ(x,y,z)=x+y+z )
• Third Ψ(-x,-y,-z)=-Ψ(x,y,z)
level
A spin 0 positive parity particle is a “scalar”
Fourth
level
A •spin
0 negative
parity particle is a “pseudoscalar”
The
conjugation (C) of a Higgs particle is +
• charge
Fifth level
charge conjugation turns a particle into its antiparticle
The Quantum numbers of a Higgs: JPC=0++
The Quantum numbers of a photon: JPC=1-A spin 1 particle is a “vector” particle
The photon is a massless vector boson
The Z is a massive (~90X proton) vector boson
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The Standard Model’s Building Blocks
1964
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to(pre-)
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MasterModel
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Third level
Fourth level
Fifth level
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A brief higgstory of HEP theory
1950’s-early 1960’s:
Search for a theory that has both massive & massless particles
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field theories (other than QED) give unphysical results
field theory Vs S-matrix theory (looks like S-matrix will win….)
Nambu-Goldstone theorem predicts massless scalar particles
But no experimental
• Second
level evidence for massless scalars
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1964:
• Third
level in PRL on avoiding massless scalars
3 papers
published
“Broken Symmetry and the Mass of Gauge Vector Mesons, “ Englert, F. & Brout, R.
PRL 13 (1964) 321-323
• Fourth level
“Broken
Symmetries
• Fifth
leveland the
PRL 13 (1964) 508-509
Masses of Gauge Bosons ,” Higgs, Peter W.
“Global Conservation Laws and Massless Particles,” G.S. Guralnik, C.R. Hagen,
T.W.B. Kibble, PRL 13 (1964) 585-587
And let’s not forget:
“Plasmons, Gauge Invariance, and Mass,” Anderson, Philip W. Phys. Rev. 130 (1963) 439-442
“Quasi-Particles and Gauge Invariance in the Theory of Superconductivity,” Yoichiro Nambu,
Phys. Rev. 117, (1960) 648
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What did these papers do?
Higgs takes a theory from Goldstone & shows that with a suitable
gauge transformation & a spontaneously broken symmetry the particle
spectrum contains only a massive scalar & a massive vector.
Gauge transformation
leaves
Maxwell’s
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toEqsedit Master text styles
invariant:
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• Second level
• Third level
• Fourthbroken
level
A spontaneously
symmetry
• Fifth
level
V(φ)
Ā=vector potential
Ā‘→Ā +θ
V=scalar potential
V’→V- θ t
-μ/λ
+μ/λ
φ
V(φ)=-½μ2φ2+¼λ2φ4
V’(φ)=0 for φ=0, ± μ/λ
V’’(μ/λ)>0
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Higgs-steria??
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Whatto
is the
reaction
to these papers?
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All the papers are ignored…..
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Yearly citations for Higgs, PRL 13 (1964) 508
Second level
1964-70: 14 citations!
To date: > 3000 citations.
Third level
Other papers have same
Fourth level
citation history!
Fifth level
(including self-cites)
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Higgs-steria??
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titlenotice?
style
What
happened
to make
people take
NOT: “A Model of Leptons,” Weinberg, PRL 19 (1967) 1264 (>9000 cites)
AND
NOT: “Regularization and Renormalization of Gauge Fields,”
Gerard 't Hooft, M.J.G. Veltman Nucl.Phys. B44 (1972) 189-213
• Second
level
(> 3300
cites)
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• Third
level (Z) interactions were observed!
Neutral
Current
A new interaction where a neutral spin 1 particle couples to a neutrino.
• Fourth level
• Fifth level
No muon produced
by interacting neutrino
V
F J Hasert et al. 1973a Phys. Lett. 46 121.
F J Hasert et al. 1973b Phys. Lett. 46 138.
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Mass Higgs-steria
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>1000 citations
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Nuclear Physics B106 (1976) 292
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Second level
Third level
Fourth level
Fifth level
Unitarity puts an upper bound on the mass
of the Higgs ≈ 1 TeV
1990
found
here !
This book has
its own
facebook page*!
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*https://www.facebook.com/pages/The-Higgs-Hunters-Guide/412484908831857
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Standard Model Higgs Predictions
The mass of the Higgs is not predicted in the standard Model.
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it is a free parameter
But how often it is produced in pp collisions Vs Higgs mass is!
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• Second level
• Third level
Gluon Fusion Vector-Boson
• Fourth level
Fusion
• Fifth level
Higgs-strahlung
Cross section for pp-> Higgs Vs MHiggs
LHC at 8 TeV CM energy produces ~1000 Higgs/hr
but we detect only a few a day L
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Standard Model Higgs Predictions
The mass of the Higgs is not predicted in the standard Model.
But how often it decays into quarks, leptons, and vector bosons
as a function of Higgs mass is!
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Higgs Branching fraction vs MHiggs
• Second level
MHiggs= 125 GeV
• Third level
• Fourth level
• Fifth level
hardest
detection
easiest
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The Large Hadron Collider
The LHC collides protons
Center of Mass E=14 TeV ~7X Fermilab
Very high luminosity ~100X Fermilab
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LHC is located at CERN
CERN is in France & Switzerland
CERN is located near Geneva
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1232 superconducting dipole magnets B=~8T
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Second level
Third level
Fourth level
Fifth level
ATLAS
site
9km
main lab
5/29/2012
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The ATLAS Experiment
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• Second level
• Third level
outside
good momentum, energy, & vertex
• Fourth level
detector
resolution
Identify muons, electrons, photons
• Fifth level
Reconstruct b-jets, taus
flexible triggers
Hermetic detector: can look for
missing energy signatures
inside
detector
Optimized to look for Higgs particles & BSM physics processes13
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pp-> Z->μ+μ-+ other stuff
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Click to edit Master text styles~100x106 collisions/s
Most are uninteresting
Second level
Third level
Fourth level
Fifth level
Many collisions
within 50 ns.
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Higgs->γγ Candidate
To “find” a particle calculate the invariant mass of its decay products
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2 energetic
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Second
level
gammas
• Third level
• Fourth level
• Fifth level
Invariant Mass of two particles:
m2=(E1+E2)2-(P1+P2)2
For photons:
m2=Eγ1Eγ2(1-cosθ)
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Higgs Particle Discovery Modes
Make
invariant
mass plots
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H->ZZ*->4 leptons
H->γγ
+e-e+e- /μ+μ-μ+μ- /e+e-μ+μ-)
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Second level
Third level
Fourth level
Fifth level
Also observed: H->WW*, H->bb, and H->τ+τHiggs decay into dibosons, quarks, and leptons
All decay channels consistent with mass=125 GeV
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The standard model is “complete”
we done? title style
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Fourth level
Fifth level
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Beyond the standard model
Many important issues remain!
The standard model is incomplete:
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Cannot predict the mass of the Higgs or how many Higgs particles.
The minimum is one, but there can be more!
Does not contain dark matter or dark energy.
Magnitude of CP violation for baryon asymmetry (CKM CPV too small)
• Second
level
No
gravity
Neutrino mass ?
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• Third level
Why
generations
• three
Fourth
levelof quarks and leptons & >19 parameters?
The “Hierarchy” problem:
Why
is the Higgs
• Fifth
levelso light compared to the Planck scale: 102 Vs 1019 GeV
Technical problems:
Quantum corrections to the Higgs mass are larger than 125 GeV.
Corrections must cancel at an amazing level: implies fine tuning to 1 part in ~1030
Muv~Mplanck~1019 GeV
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Going Beyond the Standard Model
Supersymmetry is a popular BSM with an extended Higgs sector
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to
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SUSY is a theory with symmetry between fermions & bosons.
For every SM particle there is a SUSY particle with spin that differs by ½.
Eliminates hierarchy problem
SUSY compatible with string theory & SM
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Natural extension to grand unified theories
•
Second level
Lightest SUSY particle may be stable and might be dark matter
SUSY may contain a new conserved quantum number, R
• ThirdB=baryon
level#, L=lepton #, S=spin, R=1 for SM, -1 for SUSY particles
R=(-1)
If R is conserved, SUSY particles must be produced in pairs.
• Fourth level
BUT SUSY has ~ 100 free parameters!
• Fifth level
Many possible models to consider, masses of SUSY particles unspecified.
3(B-L)+2S
Minimal Supersymmetric Model (MSSM)
5 Higgs particles:
3 neutral scalars (2 CP even, 1 CP odd), 2 charged scalars, H±
Next-to-Minimal Supersymmetric Model (NMSSM)
7 Higgs particles
5 neutral scalars (3 CP even, 2 CP odd), 2 charged scalars, H±
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Many BSMs with Higgs Particles
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Minimal Composite Higgs Model (MCHM)
(1 Higgs)
Higgs boson = composite (pseudo-Nambu-Goldstone boson)
strong interaction to the rescue => no hierarchy problem
• Click to edit Master text styles (2 Higgs)
Single additional electroweak singlet
simplest
extension,
• Second
level two CP-even Higgs bosons
Two Higgs Doublet Models (2HDM)
(5 Higgs)
• Third level
additional
doublet h0, H0 (CP-even), A0 (CP-odd), H±
=> fixeslevel
hierarchy problem
• Fourth
4 types based on coupling structure (Type II = MSSM)
• Fifth level SUSY (NMSSM)
Next-to-Minimal
(7 Higgs)
MSSM + complex singlet(S): H1, H2, H3, A1, A2, H±
=>generates MSSM μ-term through S spontaneous symmetry breaking
Higgs Triplet Model
h0, H0 (CP-even), A0 (CP-odd), H±, H±±
=> generates neutrino masses/mixings
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(7 Higgs)
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Which Higgs have we found?
Is the 125 GeV Higgs consistent with the standard model?
Detailed studies show quantum numbers are consistent with JPC=0++
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scalar Vs pseudoscalar
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Can rule out spin 1, 2,
mixtures, etc.
• Second level
• Third level
Couplings & branching fractions to fermions & vector bosons are SM.
• Fourth level
Higgs Coupling Vs mass
• Fifth level
All production & decay measurements are consistent with SM!
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Direct Higgs Searches
Search
for additional
Higgs/scalar
particles…
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Generic searches looking for H->γγ, ZZ(*), WW(*), bb, tt, etc
Look for more massive versions of H(125)
±, cs, τν, etc
Charged
Scalars
H±->ZW
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text styles
predicted by SUSY & other BSMs
• Second
level
Scalars
that decay
into other scalars
can happen if m >2*(125 GeV)
• Third level
Scalars that violate lepton number (e.g. H-> τμ)
• Fourth
level
possible
in SUSY
and Randall Sundrum models
Scalars
thatlevel
decay into undetectable particles
• Fifth
Since Higgs couples to mass decays into neutrinos highly suppressed
Unaccounted for “missing” energy in the detector
Look for another H->γγ
No evidence up to ~600 GeV
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Summary
We have
foundto
a scalar
predicted
by Higgs.
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Its mass is 125 GeV
Englert & Higgs
-->
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All particles of the standard model are now accounted for.
• Second level
BUT:
We•need
“new”
physics to explain why the SM works so well.
Third
level
We need “new” physics to explain the physics not in the SM.
Fourth
level
The• most
popular
NP models have additional “Higgs” Bosons.
• Fifth
level
Despite
intense
efforts by ATLAS and CMS there is no evidence for any
additional scalar particles in the range 100 GeV < m < ~ 1 TeV
The next chapter in the hunt for more Higgs bosons begins in a few months
when ATLAS & CMS start collecting 13 TeV CM energy data.
LHC plans to take data until 2035!
How much longer will the Higgs be lonesome?
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Extra Slides
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Second level
Third level
Fourth level
Fifth level
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Impact of the BIG 4 PRL Papers
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Plasmons, Gauge Invariance, and Mass
Anderson, Philip W.
Phys.Rev. 130 (1963) 439-442
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Second level
Third level
Fourth level
Fifth level
Broken Symmetry and the Mass
of Gauge Vector Mesons
Broken Symmetries and the
Masses of Gauge Bosons
Phys.Rev.Lett. 13 (1964) 321-323
Phys.Rev.Lett. 13 (1964) 508-509
Englert, F. & Brout, R.
Higgs, Peter W.
Global Conservation Laws
and Massless Particles
G.S. Guralnik, C.R. Hagen,
T.W.B. Kibble
Phys.Rev.Lett. 13 (1964) 585-587
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ATLAS & CMS
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• Click to edit Master text styles
• Second level
• Third level
• Fourth level
Fifth level
Both• detectors
have good momentum, energy, and vertex resolution
Identify muons, electrons, photons
Reconstruct b-jets, taus
flexible triggers
Hermetic detectors: can look for missing energy signatures
Optimized to look for Higgs particles
& Beyond Standard Model (BSM) physics processes
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Discovering the Standard Model at the LHC
Before you can discover new physics must discover the old physics.
Standard Model has many predictions for cross sections.
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Excellent test of how well the ATLAS detector works.
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Second level
Third level
Fourth level
Fifth level
cross section
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Measurements & predictions agree over ~ 12 orders of magnitude
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Which Higgs have we found?
Is the 125 GeV Higgs consistent with the standard model?
Detailed studies show that quantum numbers are consistent with JPC=0++
Click to edit Master title style
Rule out spin 1, 2, mixtures, etc.
H  ZZ *  l1l2l2l2
• Click to edit Master text styles
• Second level
• Third level
Are couplings & branching fractions to fermions & vector bosons SM? YES!
• Fourth
Higgslevel
Coupling Vs mass
Higgs branching fractions
• Fifth level
All production & decay measurements are consistent with SM!
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Search for charged Higgs, H±
Search for Charged H± →W± Z
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Second level
Third level
Fourth level
Fifth level
No signal, set model dependent limits
Many other searches for more Higgs particles: h0, H± & H±±
No signals, set limits that depend on mass and x-section
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Which Higgs have we found?
Is the 125 GeV Higgs consistent with the standard model?
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Measure Higgs branching fractions & compare with standard model
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Second level
Third level
Fourth level
Fifth level
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What is next?
The LHC is preparing to operate at 13/14 TeV CM energy
Higher CM energy = 1.75X more H(125)’s
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Second level
Third level
Fourth level
Higgs production modes
Fifth level
Higgs cross section
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LHC luminosity to increase 2X + more days taking data
>10X increase in H(125) sample in ~ 3 years
LHC has a plan to take data that goes until 2035!
Will increase sensitivity to finding additional Higgses by >100X
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Going Beyond the Standard Model
Supersymmetry is a popular BSM with an extended Higgs sector
Click
to
edit
Master
title
style
SUSY is a theory with symmetry between fermions & bosons.
For every SM particle there is a SUSY particle with spin that differs by ½.
Eliminates hierarchy problem
SUSY compatible with string theory & SM
• Click to edit Master text styles
Natural extension to grand unified theories
•
Second level
Lightest SUSY particle may be stable and might be dark matter
SUSY may contain a new conserved quantum number, R
• ThirdB=baryon
level#, L=lepton #, S=spin, R=1 for SM, -1 for SUSY particles
R=(-1)
Because of R conservation, SUSY particles must be produced in pairs.
• Fourth level
SUSY
predicts
lots of new particles besides more Higgses:
• Fifth
level
3(B-L)+2S
bosons
squark
slepton
Higgs
gluon
W, Z
photon
fermions
quark
lepton
Higgsino
gluino
Wino+Zino
photino
~
~
W   H   ~   charginos
~ ~
~
~  Z  h 0  H 0  ~ 0  neutralino s
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Which SUSY model?
SUSY
has
~ 100
free parameters
!
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to
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title
style
Many possible models to consider…
Mass of SUSY particles unspecified….
• Click to edit Master text styles
5• Higgs
particles
Second
level
2 neutral scalars (CP even), h, H
charged level
scalars, H+, H•2 Third
mass constraints
1 neutral pseudo-scalar (CP odd), A mh≤mA≤mH
Two
free parameters
• Fourth
level at tree-level: mH±2=mA2+mW2
mA & tanβ (VEV ratio of doublets)
• Fifth
level
Higgs
couplings:
up-type fermions: ~1/tanβ, down-type fermions ~tanβ
Minimal Supersymmetric Model (MSSM)
Next-to-Minimal Supersymmetric Model (NMSSM)
7 Higgs particles
3 neutral scalars (CP even), H1, H2, H3
2 charged scalars, H+, H2 neutral pseudo-scalar (CP odd), A1, A2
CP violation possible
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Higgs Decay to γγ/ZZ*/WW*
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H->γγ
No evidence up to ~600 GeV
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• Second level
• Third level
(*) → 4leptons
H→
ZZ
• Fourth level
No evidence up to ~900 GeV
ATLAS-CONF-2013-013
• Fifth level
ATLAS: arXiv:1407.6583 [hep-ex]
CMS-PAG-HIG-14-006
CMS: Phys. Rev D 89. 092007
H->WW(*)
No evidence up to ~1000 GeV
ATLAS-CONF-2013-067 CMS-HIG-13-023
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What is next?
The LHC is preparing to operate at 13/14 TeV CM energy
ClickHigher
to CM
edit
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style
energy
(1.75X) + moretitle
data (100X)
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H → ZZ → 4l
Second level
Third level
>10X increase in H(125)
Greatly increased sensitivity
sample in
~ 3 years
Fourth
level
Fifth level
(*)
LHC has a
20 year plan!
now
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Constraints from Higgs(125) measurements
ATLAS-CONF-2014-010
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Use SM Higgs coupling measurements from γγ, ZZ, WW, bb, ττ
Type II 2HDM
Exclusions in plane of m(A) vs tanβ
tanβ= VEV ratio of doublets
α=h & H mixing angle
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in a simplified MSSM model
(no new decay mode other than SM's)
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Second level
Third level
Fourth level
Fifth level
Also, exclusion plots for Type I, III, IV models
4/7/2015 with SM-like alignment, cos(β –α)~0
Consistent
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Invisible Higgs Decays
ATLAS: Phys. Rev. Lett. 112, 201802 (2014)
CMS: Eur. J. C74 (2014) 2980
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Invisible decays predicted in several models:
neutralinos (SUSY) , graviscalars (extra D’s)
Invisible decay of Higgs via ZH (ATLAS, CMS) or VBF (CMS)
Signature is m(ll) close to Z mass, no jets, ll-system balances missing ET
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Second level
Good agreement between
Third level
data & SM bkgd predictions
Fourth level
Fifth Br
level
inv < 58% @ 95% CL for m=125 GeV SM Higgs
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Invisible Higgs Decays to Dark Matter
ATLAS: Phys. Rev. Lett. 112, 201802 (2014)
CMS: Eur. J. C74 (2014) 2980
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toportal
editto Master
Higgs
Dark Mattertitle style
Hidden sector with DM particles
MasterCould
textcontribute
styles to Γinv if mass <mh/2
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• Second level
Convert
Brinv tolevel
DM-nucleon cross section assuming ΓSM total Higgs width
• Third
Consider vector, scalar, fermion DM models
• Fourth level
Limits up to mh/2
• Fifth level
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H → ZZ → 4ll Direct Search
ATLAS-CONF-2013-013
CMS: Phys. Rev D 89. 092007
Click to edit Master title style
Look for a heavy Higgs boson with SM (narrow) width
Signature is two opposite sign same-flavor lepton
leptons have large pT
3 categories
• Click (VBF/VH/ggF-like)
to edit Master text styles
fit m(llll)
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Third level
Fourth level
Fifth level
A4/7/2015
heavy Higgs with SM width is excluded up to ~800 GeV
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H → WW → μνeν Direct Search
ATLAS-CONF-2013-067
CMS-HIG-13-023
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Look for a heavy Higgs boson with SM or narrow width
Signature is two opposite-sign high-pT leptons with
•different
Click toflavors,
edit Master
text Estyles
large missing
T, high m(ll), b-jet veto
Cut•& Second
template based,
level fit MT (W)
• Third level
• Fourth level
• Fifth level
A 4/7/2015
Higgs with SM width is excluded from 260 to 642 GeV
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H→ WW → μνeν
ATLAS-CONF-2013-027
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title
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Type Ito edit Master
Type
II
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α=h & H mixing angle
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Second level tanβ= 1
Third level
Fourth level
Fifth level
tanβ= 20
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Model independent h/H/A → ττ
ATLAS: arXiv:1409.6064 CMS: Submitted to JHEP (arXiv:1408.3316)
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fusionMaster text
b associated
• Second
No
signal out level
to m ~ 1000 GeV
Calculate
• Third upper
levellimits (to cross section)x(cross section)
• Fourth level
• Fifth level
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R. Kass
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MSSM h/H/A → ττ
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Search for narrow width neutral Higgs
• Click to edit Master text styles
Signature is decay to two τ’s
Use
3 τ final states,
• Second
level (lep-had, had-had, lep-lep)
Set limits on tanβ vs m(A) for several MSSM scenarios: max, mod+, modATLAS: arXiv:1409.6064
• Third
level
• Fourth level
• Fifth level
CMS: Submitted to JHEP (arXiv:1408.3316)
max
4/7/2015
constant mh=red
constant mH=blue
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MSSM h/H/A → ττ
ATLAS: arXiv:1409.6064
CMS: Submitted to JHEP (arXiv:1408.3316)
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Second level mod+
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mod-
mod-
mod+
4/7/2015
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Lepton Flavor Violating Higgs Decays
CMS-PAS-HIG-14-005
Decays possible in 2HDM and Randall-Sundrum models
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Search for H(125)➞μτ where τ decays to electron or hadron(s)
μτ have opposite charge
Similar signature as h/H/A ➞ττ analysis, but different kinematics
Search is done in jet multiplicity bins (0, 1, 2 (VBF) jets)
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Second level
Yukawas couplings: Y
use Γ =4.1 MeV & m=125 GeV
Third level
m
(h  l l ) 
(| Y |  | Y | )
8

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SM
 
h
2
2
l l 
l  l
Upper limit of BR(H➞μτ) of ~1.5% @ 95% CL
Best fit yields BR(H➞μτ) = (0.89 ± 0.39)% ~2.5σ (compatible with 0)
Best limits on flavour-violating τμ Yukawa couplings
Generating recent theory buzz:
4/7/2015
arXiv:1412.3671
(Heeck, Holthausen, Rodejohann, Shimizu)
arXiv:1409.7690 (Aristizabal Sierra, Vicente)
R. Kass
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45
Search for H± Cascade
ATLAS: Phys. Rev. D 89, 032002 (2014)
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H → WH → WWh → WWbb
0
+
0
Search for a charged Higgs in a cascade of a
W pair and a bb-pair
Signature is one high pT lepton, large missing ET,
≥•4 jets,
≥ 2 b-jets
Second
level
Fit using boosted decision-tree distribution
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Third
Set• limits
on level
cross section as a function
of both
H± andlevel
H0 mass
• Fourth
Observed 95% CL limits
Limits on σ(gg→ H0 )obs/ σ(gg→ H0 )2HDM-II
• Fifth level
4/7/2015
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Search for Charged H → cs
ATLAS: Eur. Phys. J. C, 73 6 (2013) 2465
CMS: CMS-PAS-HIG-13-035
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Search for a charged Higgs that decays 100% into cs
• dominant
Second
level
(cs
for tan
β <1)
Signature is one high pT lepton, large missing ET,
≥• 4 Third
jets, ≥ 2 level
b-jets, two light jets
mjj close to mH ±, mH ±< mt
• Fourth level
Kinematic fit constraining tt system
Setlevel
limits on BR(t → bH±)
• Fifth
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X → H(125)H(125)
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Search for a heavy neutral resonance (X) with narrow width
that decays into 2 H(125)’s
Decays predicted by SUSY 2Higgs doublet & Randall–Sundrum models
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X → HH → bbγγ
X → HH → bb bb
Second level
Third level
Fourth level
Fifth level
ATLAS: arXiv:1406.5053
CMS-PAS-HIG-13-032
ATLAS-CONF-2014-005
CMS-PAS-HIG-14-013
Model dependent limits out to mH ~ 1000 GeV
4/7/2015
R. Kass
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X → hh → bbγγ
ATLAS: arXiv:1406.5053
CMS-PAS-HIG-13-032
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Signature is 2 isolated high p photons, two b-jets
Search for a heavy neutral resonance (X) with narrow width
T
Cut based analysis, set window around 125 GeV for each h
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Second level
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Set upper limits on gg → X → hh production
95%4/7/2015
CL UL on the x-section of non-resonant Higgs pair production <2.249pb
R. Kass
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X → hh → bbbb
ATLAS-CONF-2014-005
CMS-PAS-HIG-14-013
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Search for a heavy neutral resonance (X)
Signature is 4 b-jets from two boosted dijets
Cut based fit on m(bbbb)
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Second level
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limits on gg → X → hh → bbbb
FifthSet
level
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2HDM Scorecard
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5 Higgs particles, two Higgs doublets:
2 neutral scalars, h, H (CP-even)
2 charged scalars, H+, H1 neutral pseudo-scalar, A (CP-odd)
Separate VEVs for each doublet: v12 + v22=(246 GeV)2 tanβ = v2/v1
Parameters:
mh, mlevel
H, mA, mH±, tanβ, α (mixing angle of h & H)
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Suppress FCNCs
MSSM
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• Third level
• Fourth level
• Fifth level
4/7/2015
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Higgs Couplings- interpretation
ATLAS-CONF-2014-010
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Second level
Third level
Fourth level
Fifth level
4/7/2015
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H→ WW → μνeν
ATLAS-CONF-2013-027
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• Click to edit Master text styles
Search
for a neutral,
narrow width heavy Higgs
• Second
level
When analyzing the data include both h and H in the fit
plots
for M vs cos(α)
with α the mixing angle of h and H
•Contour
Third
level
Signature is 2 different flavor high pT leptons, large missing ET
jets for ggF,
2 jets for VBF
• 0Fourth
level
Use ANN NeuroBayes®
• Fifth level
H
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