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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

Loop Corrections to Higgs Mass2

- Consider generic fermion and boson loops:
- Each is quadratically divergent: ∫Λd4k/k2
- Leading divergence cancelled if
Supersymmetry!

2

∙2

Other Reasons to like Susy

It enables the gauge couplings to unify

It predicts mH < 150 GeV

As suggested

by EW data

JE, Nanopoulos, Olive + Santoso: hep-ph/0509331

Approved by Fabiola Gianotti

that most of the

matter in the

Universe is

invisible

Dark Matter

Lightest Supersymmetric particles ?

We shall look for

them with the

LHC

Minimal Supersymmetric Extension of Standard Model (MSSM)

- Particles + spartners
- 2 Higgs doublets, coupling μ, ratio of v.e.v.’s = tan β
- Unknown supersymmetry-breaking parameters:
Scalar massesm0, gaugino massesm1/2,

trilinear soft couplingsAλ, bilinear soft couplingBμ

- Often assume universality:
Singlem0, singlem1/2, singleAλ,Bμ: not string?

- Called constrained MSSM = CMSSM
- Minimal supergravity (mSUGRA) predicts additional relations for gravitino mass, supersymmetry breaking:
m3/2 = m0,Bμ = Aλ – m0

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

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 χ

Gravitino

(nightmare for astrophysical detection)

gμ - 2

Constraints on Supersymmetry- Absence of sparticles at LEP, Tevatron
selectron, chargino > 100 GeV

squarks, gluino > 250 GeV

- Indirect constraints
Higgs > 114 GeV, b -> s γ

- Density of dark matter
lightest sparticle χ:

WMAP: 0.094 < Ωχh2 < 0.124

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

Current Constraints on CMSSM

Different

tan β

sign of μ

Impact of

Higgs

constraint

reduced

if larger mt

Focus-point

region far up

JE + Olive + Santoso + Spanos

Sparticles may not be very light

Full

Model

samples

← Second lightest visible sparticle

Detectable

@ LHC

Provide

Dark Matter

Dark Matter

Detectable

Directly

Lightest visible sparticle →

JE + Olive + Santoso + Spanos

Missing Energy Detection @ LHC

Sensitive to missing transverse energy

carried away by neutral particles:

e.g., neutrinos, neutralinos

Supersymmetry Searches at LHC

LHC reach in

supersymmetric

parameter space

`Typical’ supersymmetric

Event at the LHC

Can cover most

possibilities for

astrophysical

dark matter

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

SparticleSignaturesalongWMAPlines

Relatively small

branching ratios in CMSSM

Z

h

Average numbers

of particles per

sparticle event

τ

3l

Battaglia, De Roeck, Gianotti, JE, Olive, Pape

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

Can one estimate the scale of supersymmetry?

Precision Observables in SusySensitivity to m1/2

in CMSSM

along WMAP lines

for different A

mW

tan β = 10

tan β = 50

sin2θW

Present & possible

future errors

JE + Heinemeyer +Olive +Weiglein

MoreObservables

tan β = 10

tan β = 50

b → sγ

tan β = 10, 50

Bs → μμ

gμ- 2

JE + Heinemeyer +Olive +Weiglein

Global Fits to Present Data

Including mW , sin2θW, b → sγ, gμ - 2

As functions of m1/2 in CMSSM for tan β = 10, 50

JE + Heinemeyer +Olive +Weiglein

χ2,χ±

Global Fitsto Present Dataχ3,χ2±

τ1

Preferred

sparticle

masses for

tan β = 10

e1

e2

JE + Heinemeyer +Olive +Weiglein

t1

t2

Global Fitsto Present Datab1

b2

Preferred

sparticle

masses for

tan β = 10

g

A

Within reach of LHC!

JE + Heinemeyer +Olive +Weiglein

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)

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!

Non-Universal Higgs Masses (NUHM)

- Generalize CMSSM (+)
mHi2 = m02(1 + δi)

- Free Higgs mixing μ,
pseudoscalar mass mA

- Larger parameter space
- Constrained by vacuum
stability

Sampling of (m1/2, m0) Planes in NUHM

New vertical

allowed strips

appear

JE + Olive + Santoso + Spanos

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

Sparticles may not be very light

Full

Model

samples

← Second lightest visible sparticle

Detectable

@ LHC

Provide

Dark Matter

Dark Matter

Detectable

Directly

Lightest visible sparticle →

JE + Olive + Santoso + Spanos

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 χ

Gravitino

(nightmare for astrophysical detection)

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 χ

lightest slepton, probably lighter stau

- Constrained by astrophysics/cosmology

Gravitino

masses

DifferentRegions of SparticleParameterSpace ifGravitino LSPχ NLSP

stau NLSP

Density below

WMAP limit

Decays do not affect

BBN/CMB agreement

JE + Olive + Santoso + Spanos

region

stau LSP

(excluded)

Gravitino LSP

region

tan β fixed by vacuum conditions

Minimal Supergravity Model (mSUGRA)More constrained than CMSSM: m3/2 = m0, Bλ = Aλ – 1

Excluded by b s γ

LEP constraints

Onmh, chargino

JE + Olive + Santoso + Spanos

Light Nuclei: BBN vs CMB

Good agreement for D/H, 4He: discrepancy for 7Li?

Observations

Calculations

Cyburt + Fields + Olive + Skillman

Constraints on Unstable Relics

- 7Li < 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

DifferentRegions of SparticleParameterSpace ifGravitino LSP

χ NLSP

stau NLSP

Density below

WMAP limit

Decays do not affect

BBN/CMB agreement

JE + Olive + Santoso + Spanos

Benchmarks

GDM

Benchmarks

Regions Allowedin Different Scenarios forSupersymmetryBreakingNUHM

Benchmarks

with neutralino NLSP

with stau NLSP

De Roeck, JE, Gianotti, Moortgat, Olive + Pape: hep-ph/0508198

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

Properties of NUHM and GDM Models

- Relic density ~ WMAP in NUHM models
- Generally < WMAP in GDM models
Need extra source of gravitinos at high temperatures, after inflation?

- NLSP lifetime: 104s < τ < few X 106s

De Roeck, JE, Gianotti, Moortgat, Olive + Pape: hep-ph/0508198

χh, χZ may be

large in NUHM

Neutralino Masses and Decay Modesχh, χZ small

in CMSSM

De Roeck, JE, Gianotti, Moortgat, Olive + Pape: hep-ph/0508198

Final States in GDM Models with Stau NLSP

- All decay chains
end with lighter stau

- Generally via χ
- Often via heavier
sleptons

- Final states contain
2 staus, 2 τ,

often other leptons

De Roeck, JE, Gianotti, Moortgat, Olive + Pape: hep-ph/0508198

Kinematic Distributions: Point ε

- Staus come with
many jets & leptons

with pT hundreds of GeV,

produced centrally

De Roeck, JE, Gianotti, Moortgat, Olive + Pape: hep-ph/0508198

Kinematic Distributions: Point ζ

- Staus come with
many jets & leptons

with pT hundreds of GeV,

produced centrally

De Roeck, JE, Gianotti, Moortgat, Olive + Pape: hep-ph/0508198

Stau Mass Measurements by Time-of-Flight

- Event-by-event
accuracy < 10%

- < 1% with full sample

De Roeck, JE, Gianotti, Moortgat, Olive + Pape: hep-ph/0508198

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

Stau Momentum Spectra

- βγ typically peaked ~ 2
- Staus with βγ < 1 leave central tracker
after next beam crossing

- Staus with βγ < ¼ trapped inside calorimeter
- Staus with βγ < ½ stopped within 10m
- Can they be dug out?

De Roeck, JE, Gianotti, Moortgat, Olive + Pape: hep-ph/0508198

Very little room for water tank in LHC caverns,

only in forward directions where few staus

Extract Cores from Surrounding Rock?- Use muon system to locate impact point on cavern wall with uncertainty < 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

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

Detect Supersymmetric Decay Albedo?

- Look for staus stopping ~ 10m from detector
- Later decay → τ + gravitino
- τ → 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 ε

De Roeck, JE, Gianotti, Moortgat, Olive + Pape: hep-ph/0508198

Caveat Cosmic-RayBackground

- Background of cosmic-ray μ
~ 100 events/year

- Similar energy range
- Signal might be visible in
benchmark scenario ε

- Not in scenarios ζ and η

De Roeck, JE, Gianotti, Moortgat, Olive + Pape: hep-ph/0508198

Potential Measurement Accuracies

Gravitino Dark Matter even more interesting

than Neutralino Dark Matter!

Measure staumass to 1%

Measure m½ to 1%

via cross section, other masses?

Distinguish points ζ, η

De Roeck, JE, Gianotti, Moortgat, Olive + Pape: hep-ph/0508198

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!

Elastic Scattering Cross Sections

From global fit to accelerator data

Latest experimental upper limit

JE + Olive + Santoso + Spanos: hep-ph/0502001

Direct CDM detection in NUHM/LEEST

Cross section similar

in NUHM/LEEST

Cross section depends

on πN σ term

Cross section depends

on sign of μ

Some NUHM/LEEST

models already excluded

JE + Olive + Santoso + Spanos

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