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Search for Supersymmetry

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Search for Supersymmetry

- 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

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

2

∙2

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

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

- 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

- 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

- 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

- 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

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

Different

tan β

sign of μ

Impact of

Higgs

constraint

reduced

if larger mt

Focus-point

region far up

JE + Olive + Santoso + Spanos

Full

Model

samples

← Second lightest visible sparticle

Detectable

@ LHC

Provide

Dark Matter

Dark Matter

Detectable

Directly

Lightest visible sparticle →

JE + Olive + Santoso + Spanos

Sensitive to missing transverse energy

carried away by neutral particles:

e.g., neutrinos, neutralinos

LHC reach in

supersymmetric

parameter space

`Typical’ supersymmetric

Event at the LHC

Can cover most

possibilities for

astrophysical

dark matter

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

Relatively small

branching ratios in CMSSM

Z

h

Average numbers

of particles per

sparticle event

τ

3l

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

LHC almost

`guaranteed’

to discover

supersymmetry

if it is relevant

to the mass problem

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

For gauge couplings

For sparticle masses

Can one estimate the scale of supersymmetry?

Sensitivity 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

Including mW , sin2θW, b → sγ, gμ - 2

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

JE + Heinemeyer +Olive +Weiglein

χ

χ2,χ±

χ3,χ2±

τ1

Preferred

sparticle

masses for

tan β = 10

e1

e2

JE + Heinemeyer +Olive +Weiglein

t1

t2

b1

b2

Preferred

sparticle

masses for

tan β = 10

g

A

Within reach of LHC!

JE + Heinemeyer +Olive +Weiglein

Beyond the CMSSM

- 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)

- 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!

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

- Free Higgs mixing μ,
pseudoscalar mass mA

- Larger parameter space
- Constrained by vacuum
stability

New vertical

allowed strips

appear

JE + Olive + Santoso + Spanos

- 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

Full

Model

samples

← Second lightest visible sparticle

Detectable

@ LHC

Provide

Dark Matter

Dark Matter

Detectable

Directly

Lightest visible sparticle →

JE + Olive + Santoso + Spanos

Gravitino Dark Matter?

- 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)

- 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

Different

Gravitino

masses

χ NLSP

stau NLSP

Density below

WMAP limit

Decays do not affect

BBN/CMB agreement

JE + Olive + Santoso + Spanos

Neutralino LSP

region

stau LSP

(excluded)

Gravitino LSP

region

tan β fixed by vacuum conditions

More constrained than CMSSM: m3/2 = m0, Bλ = Aλ – 1

Excluded by b s γ

LEP constraints

Onmh, chargino

JE + Olive + Santoso + Spanos

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

Observations

Calculations

Cyburt + Fields + Olive + Skillman

- 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

χ NLSP

stau NLSP

Density below

WMAP limit

Decays do not affect

BBN/CMB agreement

JE + Olive + Santoso + Spanos

CMSSM

Benchmarks

GDM

Benchmarks

NUHM

Benchmarks

with neutralino NLSP

with stau NLSP

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

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

- 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

χh, χZ small

in CMSSM

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

- 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

- Staus come with
many jets & leptons

with pT hundreds of GeV,

produced centrally

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

- Staus come with
many jets & leptons

with pT hundreds of GeV,

produced centrally

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

- Event-by-event
accuracy < 10%

- < 1% with full sample

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

At different

colliders

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

- 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

- 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

- 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

- 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

- 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

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

- 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!

From global fit to accelerator data

Latest experimental upper limit

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

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