Search for Supersymmetry

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Search for Supersymmetry
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Outline

• Introduction to supersymmetry
• Phenomenology of the CMSSM
• Non-universal scalar masses?
• Non-universal Higgs masses (NUHM)
• Options for the LSP
• Gravitino dark matter
• New possibilities for collider phenomenology

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Loop Corrections to Higgs Mass2

• Consider generic fermion and boson loops
• Each is quadratically divergent ??d4k/k2
• Leading divergence cancelled if
• Supersymmetry!

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Other Reasons to like Susy
It enables the gauge couplings to unify
It predicts mH lt 150 GeV
As suggested by EW data
JE, Nanopoulos, Olive Santoso hep-ph/0509331
Approved by Fabiola Gianotti
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Astronomers say that most of the matter in
the Universe is invisible Dark Matter
Lightest Supersymmetric particles ?
We shall look for them with the LHC
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Minimal Supersymmetric Extension of Standard
Model (MSSM)

• Particles spartners
• 2 Higgs doublets, coupling µ, ratio of v.e.v.s
  tan ß
• Unknown supersymmetry-breaking parameters
• Scalar masses m0, gaugino masses m1/2,
• trilinear soft couplings A?, bilinear soft
  coupling Bµ
• Often assume universality
• Single m0, single m1/2, single A?, Bµ not
  string?
• Called constrained MSSM CMSSM
• Minimal supergravity (mSUGRA) predicts additional
  relations for gravitino mass, supersymmetry
  breaking
• m3/2 m0, Bµ A? m0

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Lightest Supersymmetric Particle

• Stable in many models because of conservation of
  R parity
• R (-1) 2S L 3B
• where S spin, L lepton , B baryon
• Particles have R 1, sparticles R -1
• Sparticles produced in pairs
• Heavier sparticles ? lighter sparticles
• Lightest supersymmetric particle (LSP) stable

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Possible Nature of LSP

• No strong or electromagnetic interactions
• Otherwise would bind to matter
• Detectable as anomalous heavy nucleus
• Possible weakly-interacting scandidates
• Sneutrino
• (Excluded by LEP, direct searches)
• Lightest neutralino ?
• Gravitino
• (nightmare for astrophysical detection)

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Constraints on Supersymmetry

• Absence of sparticles at LEP, Tevatron
• selectron, chargino gt 100 GeV
• squarks, gluino gt 250 GeV
• Indirect constraints
• Higgs gt 114 GeV, b -gt s ?
• Density of dark matter
• lightest sparticle ?
• WMAP 0.094 lt O?h2 lt 0.124

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Current Constraints on CMSSM
Assuming the lightest sparticle is a neutralino
Excluded because stau LSP
Excluded by b ? s gamma
WMAP constraint on relic density
Excluded (?) by latest g - 2
JE Olive Santoso Spanos
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Current Constraints on CMSSM
Different tan ß sign of µ
Impact of Higgs constraint reduced if larger
mt Focus-point region far up
JE Olive Santoso Spanos
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Sparticles may not be very light
Full Model samples
? Second lightest visible sparticle
Detectable _at_ LHC
Provide Dark Matter
Dark Matter Detectable Directly
Lightest visible sparticle ?
JE Olive Santoso Spanos
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Missing Energy Detection _at_ LHC
Sensitive to missing transverse energy carried
away by neutral particles e.g., neutrinos,
neutralinos
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Supersymmetry Searches at LHC
LHC reach in supersymmetric parameter space
Typical supersymmetric Event at the LHC
Can cover most possibilities for astrophysical dar
k matter
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Supersymmetric Benchmark Studies
Lines in susy space allowed by accelerators, WMAP
data
Specific benchmark Points along WMAP lines
Sparticle detectability Along one WMAP line
Calculation of relic density at a benchmark
point
Battaglia, De Roeck, Gianotti, JE, Olive, Pape
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SparticleSignaturesalongWMAPlines
Relatively small branching ratios in CMSSM
h
Z
Average numbers of particles per sparticle event
t
3l
Battaglia, De Roeck, Gianotti, JE, Olive, Pape
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Summary of LHCScapabilities and
OtherAccelerators
LHC almost guaranteed to discover supersymmetry
if it is relevant to the mass problem
Battaglia, De Roeck, Gianotti, JE, Olive, Pape
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Tests of Unification Ideas
For gauge couplings
For sparticle masses
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Precision Observables in Susy
Can one estimate the scale of supersymmetry?
Sensitivity to m1/2 in CMSSM along WMAP
lines for different A
mW
tan ß 10
tan ß 50
sin2?W
Present possible future errors
JE Heinemeyer Olive Weiglein
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MoreObservables
tan ß 10
tan ß 50
b ? s?
tan ß 10, 50
Bs ? µµ
gµ - 2
JE Heinemeyer Olive Weiglein
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Global Fits to Present Data
Including mW , sin2?W, b ? s?, gµ - 2
As functions of m1/2 in CMSSM for tan ß 10, 50
JE Heinemeyer Olive Weiglein
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Global Fitsto Present Data
?
?2, ?
?3, ?2
t1
Preferred sparticle masses for tan ß 10
e2
e1
JE Heinemeyer Olive Weiglein
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Global Fitsto Present Data
t1
t2
b1
b2
Preferred sparticle masses for tan ß 10
A
g
Within reach of LHC!
JE Heinemeyer Olive Weiglein
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Beyond the CMSSM
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More General Supersymmetric Models

• MSSM with more general pattern of supersymmetry
  breaking
• non-universal scalar masses m0
• and/or gaugino masses m½
• and/or trilinear couplings A0
• Nature of the lightest supersymmetric particle
  (LSP)
• Extended particle content
• non-minimal supersymmetric model (NMSSM)

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Non-Universal Scalar Masses

• Different sfermions with same quantum s?
• e.g., d, s squarks?
• disfavoured by upper limits on
  flavour- changing neutral interactions
• Squarks with different s, squarks and sleptons?
• disfavoured in various GUT models
• e.g., dR eL, dL uL uR eR in SU(5), all
  in SO(10)
• Non-universal susy-breaking masses for Higgses?
• No reason why not!

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Non-Universal Higgs Masses (NUHM)

• Generalize CMSSM ()
• mHi2 m02(1 di)
• Free Higgs mixing µ,
• pseudoscalar mass mA
• Larger parameter space
• Constrained by vacuum
• stability

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Sampling of (m1/2, m0) Planes in NUHM
New vertical allowed strips appear
JE Olive Santoso Spanos
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Low-Energy Effective Supersymmetric Theory

• Assume universality for sfermions with same
  quantum numbers (but different generations)
• Require electroweak vacuum to be stable (RGE not
  ? negative mass2)
• up to GUT scale (LEEST)
• up to 10 TeV (LEEST10)
• Qualitatively similar to NUHM
• not much freedom to adjust squarks/sleptons

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Sparticles may not be very light
Full Model samples
? Second lightest visible sparticle
Detectable _at_ LHC
Provide Dark Matter
Dark Matter Detectable Directly
Lightest visible sparticle ?
JE Olive Santoso Spanos
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Gravitino Dark Matter?
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Possible Nature of LSP

• No strong or electromagnetic interactions
• Otherwise would bind to matter
• Detectable as anomalous heavy nucleus
• Possible weakly-interacting scandidates
• Sneutrino
• (Excluded by LEP, direct searches)
• Lightest neutralino ?
• Gravitino
• (nightmare for astrophysical detection)

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Possible Nature of NLSP

• NLSP next-to-lightest sparticle
• Very long lifetime due to gravitational decay,
  e.g.
• Could be hours, days, weeks, months or years!
• Generic possibilities
• lightest neutralino ?
• lightest slepton, probably lighter stau
• Constrained by astrophysics/cosmology

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DifferentRegions of SparticleParameterSpace
ifGravitino LSP
? NLSP
stau NLSP
Density below WMAP limit
Decays do not affect BBN/CMB agreement
JE Olive Santoso Spanos
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Minimal Supergravity Model (mSUGRA)
More constrained than CMSSM m3/2 m0, B? A?
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Excluded by b ? s ?
LEP constraints On mh, chargino
JE Olive Santoso Spanos
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Light Nuclei BBN vs CMB
Good agreement for D/H, 4He discrepancy for 7Li?
Observations
Calculations
Cyburt Fields Olive Skillman
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Constraints on Unstable Relics

• 7Li lt BBN?
• Effect of relic decays?
• Problems with D/H
• 3He/D too high!
• Interpret as upper
• limits on abundance
• of metastable heavy
• relics

JE Olive Vangioni
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DifferentRegions of SparticleParameterSpace
ifGravitino LSP
? NLSP
stau NLSP
Density below WMAP limit
Decays do not affect BBN/CMB agreement
JE Olive Santoso Spanos
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Regions Allowedin Different Scenarios
forSupersymmetryBreaking
NUHM Benchmarks
with neutralino NLSP
with stau NLSP
De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Spectra inNUHM and GDMBenchmarkScenarios
Typical example of non-universal Higgs masses
Models with gravitino LSP
Models with stau NLSP
De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Properties of NUHM and GDM Models

• Relic density WMAP in NUHM models
• Generally lt WMAP in GDM models
• Need extra source of gravitinos at high
  temperatures, after inflation?
• NLSP lifetime 104s lt t lt few X 106s

De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Neutralino Masses and Decay Modes
?h, ?Z small in CMSSM
De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Final States in GDM Models with Stau NLSP

• All decay chains
• end with lighter stau
• Generally via ?
• Often via heavier
• sleptons
• Final states contain
• 2 staus, 2 t,
• often other leptons

De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Kinematic Distributions Point e

• Staus come with
• many jets leptons
• with pT hundreds of GeV,
• produced centrally

De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Kinematic Distributions Point ?

• Staus come with
• many jets leptons
• with pT hundreds of GeV,
• produced centrally

De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Stau Mass Measurements by Time-of-Flight

• Event-by-event
• accuracy lt 10
• lt 1 with full sample

De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Numbers of Visible Sparticle Species
At different colliders
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Slepton Trapping at the LHC?
If stau next-to-lightest sparticle (NLSP) may be
metastable may be stopped in detector/water
tank?
Trapping rate
Kinematics
Feng Smith
Hamaguchi Kuno Nakaya Nojiri
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Stau Momentum Spectra

• ß? typically peaked 2
• Staus with ß? lt 1 leave central tracker
• after next beam crossing
• Staus with ß? lt ¼ trapped inside calorimeter
• Staus with ß? lt ½ stopped within 10m
• Can they be dug out?

De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Extract Cores from Surrounding Rock?
Very little room for water tank in LHC
caverns, only in forward directions where few
staus

• Use muon system to locate impact point on cavern
  wall with uncertainty lt 1cm
• Fix impact angle with accuracy 10-3
• Bore into cavern wall and remove core of size 1cm
  1cm 10m 10-3m3 100 times/year
• Can this be done before staus decay?
• Caveat radioactivity induced by collisions!
• 2-day technical stop 1/month
• Not possible if lifetime 104s, possible if 106s?

De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Detect Staus in Mass Spectrometer?

• Each core 1cm 1cm 10m
• Region of interest 1m long
• Contains 2 1027 nucleons, i.e., 1027 protons
• Present best limits from water 10-29/proton
• Sensitivity possible in principle
• How quickly could the volume be searched?
• Have at most a few weeks!

De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Detect Supersymmetric Decay Albedo?

• Look for staus stopping 10m from detector
• Later decay ? t gravitino
• t ? µ with branching ratio 16
• Characteristic energies (1/6) mstau
• 25 to 50 GeV
• Geometric acceptance for upward-going µ 1/12 ?
  1.3 of stau decays detectable
• ? 100 events/year in benchmark scenario e

De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Caveat Cosmic-RayBackground

• Background of cosmic-ray µ
• 100 events/year
• Similar energy range
• Signal might be visible in
• benchmark scenario e
• Not in scenarios ? and ?

De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Potential Measurement Accuracies
Gravitino Dark Matter even more interesting than
Neutralino Dark Matter!
Measure stau mass to 1 Measure m½ to 1 via
cross section, other masses? Distinguish points
?, ?
De Roeck, JE, Gianotti, Moortgat, Olive Pape
hep-ph/0508198
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Summary

• The C in CMSSM signifies conservative
• Many more exotic supersymmetric phenomenologies
  are possible
• Gravitino dark matter is one example
• Not to mention breaking of R parity
• nor split supersymmetry
• Supersymmetry is the most expected surprise at
  the LHC
• Expect it to appear in an unexpected way!

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Elastic Scattering Cross Sections
From global fit to accelerator data
Latest experimental upper limit
JE Olive Santoso Spanos hep-ph/0502001
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Direct CDM detection in NUHM/LEEST
Cross section similar in NUHM/LEEST
Cross section depends on pN s term
Cross section depends on sign of µ
Some NUHM/LEEST models already excluded
JE Olive Santoso Spanos