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Seeking Supersymmetry

Paul Grannis Escolo Swieca, Campos do Jordao

Jan. 19 23, 2009

Susy

Supersymmetry is basically a simple idea.

Translating the idea into a model which can be

confronted with Nature through experiment leads

to a forest of nearly an infinite number of trees

and tangled pathways. Our aim in this lecture is

to examine some of the interesting trees but also

to gain some perspective of the forest as a whole.

My expertise as a forest ranger is limited!

Susy outline

- Supersymmetry phenomenology
- Susy breaking
- Present experimental constraints
- How much Susy space is left unexplored?
- What can we learn from the LHC?
- What will ILC add to Susy understanding?

Supersymmetry

Supersymmetry is the maximal extension of the

Lorentz group. It has fermionic generators Q, Q

which anticommute with themselves and relates

fermions and bosons (differing by ½ unit of spin)

Q bosongt fermiongt Q fermiongt bosongt

And thus puts boson and fermion into the same

multiplet, with the same mass (in the

supersymmetry limit). (Denote supersymmetry

partners sparticles ( p ) One of the largest

diseases of the SM is the hierarchy problem the

tendency of Higgs and other masses to rise to the

Planck scale without incredible fine tuning.

Supersymmetry solves this for every fermionic

loop diagram there is now a corresponding bosonic

loop with opposite sign. So there is a

cancellation in the mass divergences at every

order, diagram by diagram exact if Susy is a

perfect symmetry, but good enough even if the

fermion boson mass difference is O(1 TeV) EW

scale.

W

W

W

W

(-)

W

W

H

H

Sparticles

Every standard model spin ½ fermion (quark,

lepton) has a spin 0 partner e.g. scalar

electron, scalar up quark etc. Note that the SM

fermions have left- and right-handed states which

are degenerate due to Lorentz invariance (a boost

can turn a left handed up quark into a right

handed up quark). The Susy partners (e.g.

selectronL and selectronR), having no spin,

cannot be so related and thus their masses need

not be the same. Every standard model boson

(spin 1 gauge bosons the massless ones before

EWSB and spin 0 Higgs fields) has a spin ½

partner (wino, bino, gluino, higgsino ). For

each massless gauge boson there are two gauginos,

one for each of the 1 helicity states. In

supersymmetry we require at least two complex

Higgs doublet fields to avoid triangle anomalies.

As we have seen, 3 of these 8 degrees of freedom

are eaten to provide the zero helicity states of

W and Z and the other 5 survive as the physical

h, H, A and H. Each of these 8 Higgs fields has

its corresponding higgsino fields, with again 5

surviving as sparticles.

Susy/SM particles

particle and sparticle states (only 1st

generation shown)

Susy breaking

Recall that the SM does not yield unification of

the forces (SU(3), SU(2) and U(1) couplings do

not become equal at the GUT scale). TeV scale

Susy modifies the renormalization group evolution

so that the couplings can meet at a common

point. Susy must be a broken symmetry. There is

no scalar partner of the electron at M0.511 MeV

and no spin ½ W partner at 80.399 GeV. In the SM,

the gauge bosons in the symmetry limit must be

zero due to gauge invariance it is the EWSB

that generates the masses of W and Z. The Susy

sparticles can however have intrinsic mass terms

in the Lagrangian for squarks, sleptons,

higgsinos, gauginos all presumably at the TeV

scale. Additionally, we introduce ad hoc

trilinear couplings A governing the

squark-squark-Higgs and slepton-slepton-Higgs

vertices and bilinear couplings B of Higgs

supermultiplets. In the general Minimal

Supersymmetric Standard Model (MSSM), these mass

and couplings, and the Higgsino mass term m, are

put in as 105 arbitrary parameters, to be chosen

by Nature, to describe the Susy breaking. The 105

arbitrary parameters (ugly??) mean that it is

effectively impossible to characterize the

phenomenology for the full class of MSSM Susy

models. Thus simplifying assumptions are often

made about relations among the parameters. and,

even more complex versions of Susy than the MSSM

can be invented

Susy Lagrangian

For the record, the Susy breaking Lagrangian

And the Higgs potential

R-parity and Mixing

- Susy could violate baryon and lepton number

conservation. To prevent this, an invariance

under R parity inversion is often postulated. - R ( -1)3B-3L2S (Bbaryon ,

Llepton , S spin) - All particles have R 1 (e.g. quark with B1/3,

L0, S1/2 ), whereas all sparticles have R -1

(e.g. squark with B1/3, L0, S0). - R-parity invariance then implies that in any

reaction initiated by SM particles, there are an

even number of sparticles participating. - Thus the lightest of the sparticles LSP

(lightest Susy particle) is forbidden to decay

(to all SM particles), and is a good candidate

for the Dark Matter particle, as it would have

very small interaction cross sections and would

be cosmically stable. - Sparticles with the same quantum numbers can

mix, so the observed mass eigenstates are

mixtures of the Susy states shown in the table

above. - 2x2 mixing matrix for (charged winos and

higgsinos) ? 2 charginos c1 , c2 - 2x2 matrix for squarks (L and R) and sleptons (L

and R) ? 2 q, l states e.g. t1, t2 - Off diagonal mass matrix elements

quark/lepton mass, so large mixing for t, t - 4x4 matrix for neutral wino, bino, 2 higgsinos ?

4 neutralinos c10, c20, c30, c40

Susy breaking models

Exploring a parameter space with 105 arbitrary

parameters and trying to confront predictions

with experiment is difficult!! Simplified

models are considered, classified by the

mechanism used to break the Susy symmetry. There

seems not to be a way to break the symmetry

through choices of the MSSM parameters. SUGRA

(supergravity) Postulate some high energy

scale, F, for the symmetry with spontaneous

breaking transmitted to the TeV scale by gravity.

The sparticle masses are scaled by the Planck

scale MP as M F2/MP. Implying that F1011

GeV. In SUGRA, assume that all squarks,

selectrons and Higgs have a common mass m0 at the

GUT scale (F) and all gauginos have a common mass

m1/2. These masses evolve and diverge as they

are run down to the TeV scale. Typically squarks

and gluinos are more massive than sleptons and

gauginos, and decay through chains leading

ultimately to the LSP. The c10 is typically the

LSP and is the DM candidate. Also assume the

trilinear Higgs-sfermion-sfermion couplings have

a common value A0. This leaves the bilinear Susy

breaking term B and the higgsino mass m, but B

and m2 can be eliminated by their relation to MZ,

leaving the 5 parameters m0 m1/2

A0 tanb sgn(m) 1 In SUGRA, the lighter

chargino and neutralinos tend to be mainly

gaugino (not higgsino)-like with M(c20) M(c1)

2M(c10).

Susy breaking models

GMSB (Gauge Mediated Susy Breaking) Again

postulate a symmetry breaking at F 1010 GeV,

but transmission by SU(3)xSU(2)xU(1) gauge

interactions to the TeV scale. In this

mechanism, the Susy partner of the graviton, the

gravitino, gets its mass only through gravity and

is much lighter than all other sparticles. Now

the next to lightest Susy particle (NLSP) is

either the lightest neutralino or the stau and

decays weakly to the gravitino c10 ? G g or t1 ?

G t. Unless the NSLP is the neutralino and

lives long enough to escape the detectors, GMSB

phenomenology is quite different from SUGRA. The

photon in the NLSP decay is often a good

experimental signature. There are again 5

parameters in the simplified GMSB framework.

Anomaly mediated and Gaugino mediated Susy

breaking schemes have also been postulated. Each

has rather different characteristic sparticle

mass spectra, though even within a specific model

class wide variations can be found. Also, models

in which R-parity is violated, at least for some

of the sparticle fields, are possible (so long as

B and L conservation is retained).

What has experiment ruled out?

The mapping between experiment and Susy theory is

not good. Experiments must choose a particular

signature (specific collection of jets, leptons,

MET etc.) and see whether the rates observed

violate the prediction of a particular model.

Thus experimental results tend to be valid for a

specific Susy breaking scheme, but not generally

for the full MSSM. There are MANY specific

searches at LEP, Tevatron, HERA, and other

experiments often difficult to relate to each

other.

Examples of searches Charged slepton search at

LEP LEP operated at energies up to 208 GeV ee-

collisions and produces slepton pairs as shown

The LEP experiments have also ruled out charginos

below 103 GeV for all but a few pathological

parameter choices.

What has experiment ruled out?

The final state then consists of several jets

(2-4 depending on the mass hierarchy) and MET

from the LSP. Several optimized searches with

different number of jets and MET were performed

and compared to a series of predictions in the

(m0 m1/2 ) plane.

The plot shows the MET distribution compared to

SM backgrounds dominated by ttbar, Wjets,

Zjets. It shows possible gluino signal (heavier

gluino case). The data is well modeled by the

backgrounds, so limits can be set.

And in the m0 m1/2 plane, extending LEP

somewhat

Limits in the squark-gluino mass plane

What has experiment ruled out?

Chargino masses below about 140 GeV are ruled

out. The data are not consistent with tanb lt10

for M(c1)130 GeV.

Limits in the m0 m1/2 plane extend LEP and

previous Tevatron considerably

Is Susy still an attractive BSM idea?

There is no experimental evidence to date for

Supersymmetry no sparticles, no convincing

demonstration of new physics hiding in loops in

rare processes. So is it sensible to retain Susy

as a viable model?

- Nevertheless Susy has many very attractive

features - It cures the hierarchy problem
- Allows an explanation for EWSB that is not ad hoc
- Is thought to be an essential feature of

consistent string theories (though is not

predicted to be at low mass scale) - Provides a dark matter candidate
- Completes the Lorentz group
- Retains the agreement of existing precision

measurements with SM prediction. (many other

models tend to produce discrepancies with

experiment), and Susy reduces in many limits to

the SM at present energies.

So we are reluctant to give up on Supersymmetry

How much Susy space is left?

C. Berger, J. Hewett, J. Gainer, T. Rizzo, hep-ph

0812-0980

- Most experimental searches to date have been in

some restricted Susy model, not the MSSM.

Recently, a more general search in a model space

called pMSSM (phenomenological MSSM) in which

some simplifications are made - No CP violation in Susy parameters
- Minimal flavor violation
- Degenerate 1st and 2nd generation squarks and

sleptons

- This leaves 19 (not 105) Susy breaking

parameters - Masses for SU(3), SU(2) and U(1) gauginos (50

GeV lt Mi lt 1 TeV) - Higgsino mass m (50 GeV lt m lt 1 TeV)
- tanb (1 lt tanb lt 50)
- Higgs CP odd mass, MA (43.5 GeVlt MA lt 1 TeV)
- 10 masses for squarks and sleptons (100 GeV lt

Mf lt 1 TeV) - Trilinear couplings only for 3rd generation (b,

t, t) (Aj lt 1 TeV)

Pick parameters randomly with equal probability

in indicated ranges 107 times. Compute the Susy

spectrum and derived quantities. Require that

predictions agree with theoretical constraints or

experimental results, and keep only those models

that are consistent.

How much Susy space is left?

Flavor physics/cosmological constraints Agree

(loosely) with limits on b?sg, Bs ?mm

B?tn, gm-2, quark mixing Relic density of LSP no

greater than WDMh2 0.121 (could be non-LSP dark

matter)

Constraints employed

Theoretical constraints No tachyons No false

minima in scalar potential LSP is lightest

neutralino (Grand unification not required)

LEP/Tevatron limits on squark, chargino masses,

Higgs couplings, heavy stable particles are

obeyed.

For the 107 parameter sets chosen, 7x104 survive

all these constraints. For these, plot the

distributions of sparticle masses, Susy

parameters that are thus still compatible with

data

t1 , t2

Sleptons R sleptons tend to be lighter than

L. Stau1lt selectron/smu

e/m L and R

How much Susy space is left?

Squarks some solutions are below the Tevtron

limit 300 GeV where the searches made cuts that

eliminated them from sample.

Gauginos lowest c1 and c10 , c20 states are

quite light, often accessible to 500 GeV ILC.

How much Susy space is left?

Light Higgs h is almost always below 125 GeV

(recall in decoupling limit, h HSM). Cases

with Mh lt 110 GeV have odd couplings that evaded

the HSM search. H and A nearly degenerate, even

away from decoupling limit.

light Higgs h (log scale)

heavy Higgs H/Ah

Gluino masses rather uniformly distributed up to

upper limit.

gluino

How much Susy space is left?

c10 is the LSP by construction what is the NLSP?

Some preference for c1 and c20, but other

possibilities are also possible.

character of NLSP

What are the components in the c10 LSP after

the neutralino mass mixing? Somewhat

surprisingly it tends not be like SUGRA where c10

is mainly bino. There is a rather large fraction

of cases which are higgsino or wino dominated.

Few cases with all three significant in mixture.

LSP higgsino vs. bino fraction

LSP bino vs. wino fraction

How much Susy space is left?

tanb distribution

One can ask the probability distributions for

Susy parameters or observables in the selected

models. Most likely value of tanb is 12

Most likely value of Wh2 from the LSP is

significantly lower than observed Wh2, so it

implies there are other DM particles besides

neutralinos (axions?)

Wh2 distribution

In general, the existing constraints on

supersymmetry leave a large amount of parameter

space still unexplored. However the observables

tend to be in a range that is easily explored by

the LHC, and many states have high probability

for being seen at the ILC.

Finding Susy at LHC

The LHC produces mainly squark/gluino pairs via

known strong QCD interactions. Other sparticles

then occur in the decay chains that are quite

model dependent, and ultimately end with a

collection of SM particles and the LSP.

The LHC experiments can quickly see Susy and

determine the Susy scale. Define a variable

Meff METpT(1)pT(2)pT(3)pT(4)

from the

missing ET and pT of the four leading jets in the

event (veto on leptons)

Left plot is Meff distribution shaded histogram

is SM bknd and open circles add in Susy (760 GeV

gluino). Note log scale. Right plot is MSUSY

(Minimum of squark or gluino mass) vs. Meff. The

scale of Susy is remarkably well determined.

Most studies of Susy at LHC have been done in the

SUGRA framework, and even here there are very

different signatures over the range of possible

parameters. ATLAS and CMS have sampled this

space to get an idea of what can be done, but

these studies can only be representative.

Finding Susy at LHC

Within SUGRA models, one can scan the space to

get an idea of the discovery reach. For 10 fb-1,

requiring at least 2 jets that are not

back-to-back (for SM rejection) and significant

MET, or high pT leptons with transverse mass of

leptons and MET above the W mass, one obtains

discovery (gt10 events, good S/vB)

Lines are for different final state lepton

content.

Visually these plots look like the LEP/Tevatron

exclusion plots shown before. Dont be fooled

the axes are much expanded! (The Tevatron range

is circled) The LHC should see the effects of

Susy if it has anything to do with EWSB.

LHC should see squarks/ gluinos out to gt 2 TeV

Determining Susy parameters at LHC

It is easy to see dramatic effects at LHC if Susy

exists. The harder questions are whether one can

determine that it really is Susy, what the masses

of the sparticles are, what are the decay

branching ratios, what are the quantum numbers of

the sparticles, and what is the nature of Susy

symmetry breaking. The answers to these questions

are again very dependent on the exact Susy model

Nature has chosen. Even small changes in

parameters make large qualitative differences in

decay patterns and masses.

Decay chain example At LHCC Point 3,

M(gluino)300 GeV, M(squarks)310 GeV and gluino

pair production is dominant. A representative

decay chain g ? b1 b ( h.c.) (89)

b1 ? c20 b (86) c20 ?

c10 l l- (34)

(Gluino decays to bottom squark (and SM b) since

light squark mass exceeds gluino mass here.)

Sparticle masses from end points

End points For 2 body decay of monoenergetic

particle A (e.g. ee ? AA )whose decay A ? X

C (X unseen, C some known SM particle) is

isotropic in its decay frame, the lab frame

energy distribution for C is flat between end

points E- and E.

Knowing s, and measuring E and E-, allows

solving for MX and MA.

At the LHC (e.g. example in previous page), we

typically do not know s due to parton momentum

distribution, and usually are not dealing with a

monoenergetic particle decaying into two final

particles, but the upper end point continues to

carry information about mass differences.

Susy

Masses in gluino decay example

For our example c20 ? c10 l l- , the dilepton

mass upper end point determines the c20 - c10

mass difference (here input to be 50 GeV) to

about 0.1. (A favorable case with small

backgrounds and the large BRs.)

dilepton mass

Get M(b1) to 1 1.5DM(c10) M(g) M(b1) 10

This is a favorable scenario for LHC. Typically

get only mass differences, at the level of

10-20. And mass of c10 is known, so the

absolute scale is not fixed.

Susy at LHC

Typically LHC experiments will see evidence of

Susy in many channels, so fitting them all

together can give some information about the

underlying model parameters, assuming a

particular Susy breaking scheme. ATLAS estimates

that the precision on m0, m1/2 and tanb range

between a few and 20, after making the

assumption that it is SUGRA. It is unlikely that

the LHC experiments will measure the spins and

parities of new particles. This is critical to

establishing that what you see is Susy if you

say you see a selectron, you had better be able

to demonstrate that it has spin 0!

For example, 4 different models give same final

state particles (a) and (b) are Susy with

different DM particle. (c) and (d) are extra

dimension models with different KK state

character.

The LHC is a wonderful discovery machine, but the

reverse engineering to let us understand clearly

what is seen is difficult. This is the crux of

the argument for the lepton colliders, where the

simplicity of the reactions pays off. (But dont

sell the ingenuity of the LHC physicists short,

once they have data in hand.)

Susy at the ILC

For supersymmetry studies, the ILC is very

complementary to the LHC. Whereas the LHC seems

assured to produce most of the Susy particles,

the ILC is limited in energy (500 GeV to 1 TeV)

so if the sparticles are heavy they may be

inaccessible. (recall that sparticles are

produced in pairs) But for those sparticles that

can be produced, much more incisive measurements

are possible at ILC than at the LHC. The

colliding partons (e e-) have a fixed energy

the beam particles can be polarized to enhance

cross sections and reduce backgrounds, the

events are cleaner, and the initial state is

known. The ILC can measure the masses of the

accessible particles accurately, and can usually

determine their quantum numbers (recall that

knowing the spins is crucial for saying that what

we see is Susy). The mixing matrices can be

measured, and CP violations in these mixings can

be sought. Working together, the two machines

amplify the results of each other. For example,

the ILC can measure the mass of the LSP c10 this

allows the mass differences of the heavier

sparticles measured at the LHC to be converted to

mass measurements. And with results from both

machines, the nature of the Susy symmetry

breaking mechanism can be illuminated.

ILC smuons

Can measure both the smuon and LSP mass to lt

accuracy from runs at the maximum energy. Once

one knows the mass from the end point spectrum,

one can set the energy of the collider to near

the smuon pair threshold. In this case, the

threshold behavior is b3 (p-wave). From the

location of the threshold, one can measure the

mass more precisely (0.1 in this case).

End point mass measurements for all observable

Susy particles can be done simultaneously at full

energy. But separate threshold scans are

typically needed for each reaction.

ILC smuon Qs couplings

The threshold behavior (for smuons, b vs b3) and

the angular distribution of the final ms

determine the quantum numbers of the mR . To

verify it is Susy, the smuons should be spin 0

and there should be (non-degenerate) partners for

both left- and right-handed m. The dominant

particles produced (mR or mL pairs) can be

selected by altering the polarization of the

incident electron. Supersymmetry requires that

analogous couplings between Susy particles and SM

particles are identical. e.g. g(mnW)

g(mnW) The sparticle couplings can be directly

measured from the cross sections to verify if it

is Supersymmetry or some other model. Similar

techniques work for the selectrons (harder

because one can produce eL eR- and eR eL-

also) and staus (harder because final state ts

are harder).

ILC selectron studies

Production of selectron pairs -- have two

diagrams typically the t-channel c0 exchange

dominates and allows measurement of neutralino

couplings (gaugino vs. higgsino) to

lepton/slepton. Bkgnd WW production is suppressed

for beam eR- .

e

e

c0

e distributions for both e- polarizations

e-

e-

End point measurements for selectrons are more

complex as can reach eReR-, eReL-, eLeR-, and

eLeL- final states from same initial state.

But can disentangle to get masses.

Scan at threshold for very accurate masses Here

use e-e- since this is s-wave (b1), not p-wave

(b3) as for ee-. Can achieve 20 MeV (0.01).

Angular distributions of decay electrons e ? e

c10 with polarized beams give quantum numbers,

coupling of exchanged c10 and give information on

nature of neutralino mixing (gaugino/higgsino),

hence the underlying Susy mass parameters.

ILC chargino studies

Both s-channel and t-channel processes

contribute. Masses are measured to few from

end points in reaction e e- ? c1 c1- with

decays c1 ? c10 W or c10 ln or c10 qq. The

mass values of c1, c2 constrain the parameters

of the mixing matrix taking (WH) to the mass

eigenstates (c1, c2) and determine M2 (mass of

the SU(2) Susy boson) and m (Higgsino mass

parameter).

M2(c1)M2(c2) M22 2MW2 m2 M(c1) x M(c2)

mM2 MW2 sin(2b)

Thresholds for gaugino pairs are b1 (thus better

mass precision than for scalars).

ILC neutralino studies

The mass matrix for the 4 J1/2 neutral gauginos

(b, w3, H1, H2) depends on the U(1) and SU(2)

gaugino masses M1, M2, the higgsino mass m and

tanb. The mass matrix can be diagonalized to

give the physical state ci0, i1,4. There

are 14 possible CP violating phases in the

neutralino sector alone (46 overall in the MSSM).

Unitarity relations yield unitarity quadrangles

which in principle can be determined

experimentally, through a combination of

neutralino production cross sections, and

fermion-sfermion-neutralino vertix

determinations. These, together with the

chargino measurents, make it possible to extract

the underlying Susy parameters even in the case

of CP violation. We need to know M1eiF1, M2,

meiFm, tanb to fix the low energy Susy model.

ILC gaugino studies

Measurement of cross sections for c1 c1- and

c1 c2- with polarized beams give us M2, meiFm,

tanb

Measurement of c10 and c20 masses and s(c10 c20)

then give M1 and its phase Fm

?

?

?

CP violating observables like pe(p x p-) in

reaction ee- ? c10 c20 ? c10 c10 l l - can

directly signal CP violation.

ILC third generation sfermion studies

The (tL , tR) or (tL , tR) states mix to

non-degenerate mass eigenstates (t2 , t1) or (t1

, t2) through SM fermion Yukawa terms hence

the mixing is most pronounced for third

generation sfermions. The mass mixing matrix is

sensitive to the soft Susy-breaking parameters

and trilinear couplings

tLtR

t1t2

cosqt sinqt -sinqt cosqt

Cross sections with polarized e- , and mass of t

s, allow determination of sinqt to 0.03

(100 fb-1). Polarization of t can be determined

to 7 from the t decay asymmetry This

yields information on the c10 and t mixing (and

also yields info on tanb there are many

independent ways to measure the Susy

parameters!) tR- ? tR- Gaugino tL- ?

tL- Higgsino A valuable tool for independent

study of gaugino mixing

Using polarized e- beams, one can measure the

stop mass to 2 GeV and cosqt to 0.02. The

mixing angle can be improved to 0.001 through

measurement of ALR for t t.

Sfermion measurements allow probe of the Yukawa

Susy couplings and departures from simple mSUGRA

models.

ILC Susy studies

The Linear Collider can determine the Susy model,

and make progress to understand the high energy

supersymmetry breaking scale. To do this, one

would like to see the full spectrum of sleptons,

gaugino/higgsino states. The question is whether

the full set of Susy particles will be

kinematically accessible.

Thresholds for selected sparticle pair

productions at LHC mSUGRA model points.

Point 1 2 3 4 5

6 GeV GeV GeV GeV GeV

GeV

reaction

RED Accessible at 500 GeV BLUE added at 1 TeV

c10 c10 336 336 90

160 244 92 c10 c20 494

489 142 228 355 233 c1 c1-

650 642 192 294 464

304 c1 c2- 1089 858

368 462 750 459 e e/ m m

920 922 422 1620 396 470 t t

860 850 412 1594

314 264 Z h 186 207 160

203 184 203 Z H/A 1137 828

466 950 727 248 H H -

2092 1482 756 1724 1276

364 q q 1882 1896 630

1828 1352 1010

The pMSSM study above of models that satisfy

theoretical and expt constraints tend to confirm

that low mass c10, c20, c1 are preferred.

It is likely however that in the case that

supersymmetry exists, one will want ILC upgrades

in energy to at least 1 TeV.

ILC Susy run plan

The measurements we have outlined at ILC require

running at several different conditions (beam

particles, energies, polarizations), unlike LHC

where one runs the machine only at full 14 TeV

energy. At ILC, one wants runs at full energy to

seek new physics and measure Susy reaction end

points. Then do special runs at the thresholds

for some Susy reactions and tt production. Can

one do this program achieve the sort of precision

we have outlined in a finite time?

Examine a run scenario for the first 1000 fb-1 of

ILC running at 500 GeV (7 years). Take Mh120

GeV. Assume Susy parameters that assure many

particles are accessible, thus many run

conditions are needed. The SM2 SUGRA point gives

masses and BRs as indicated. Remember that all

Susy reactions allowed occur together, so Susy

forms an important background in many studies.

m0 100 GeV m1/2 250 GeV tanb 10 A0

0 sgn(m)

ILC Susy run plan

Cross sections are specified given the SUGRA

parameters note that L and R polarized e- XSs

differ (assume Pe- 80).

Propose run plan shown Calibrate detectors with

Z pole runs. Initial running at 500 GeV to get

Susy reaction end points. e e-threshold scans

for

ILC Susy run plan

We focus on specific decay topologies (e.g. 4

leptons and MET). Take into account that other

Susy reactions provide background and note that

several reactions may feed a particular final

state. For each channel sum the contributions

from all reactions that feed it. We choose the

e- polarization state to enhance particular

reactions of interest. Since the decay BRs and

backgrounds depend sensitively on the specific

Susy model, this exercise is an existence proof

but is not directly translatable to other models.

Sparticle mass precision achieved in 1000 fb-1

Precision on Higgs mass/couplings and top quark

parameters

Sugra parameter precision

Even for a very rich accessible Susy spectrum,

the ILC should be able to make measurements at

the desired precision.

ILC and LHC are synergistic

If Susy exists, the LSP provides a dark matter

candidate. The ILC in particular measures its

mass very accurately and the Susy cross sections

allow the calculation of the DM cosmic density.

If these agree with the density measurements from

Cosmic Microwave Background measurements, we have

provided full understanding of the character of

dark matter.

DM cosmic density ?

If the density from colliders disagrees with

mwave background, we know that there are other

contributing dark matter particles.

DM mass ?

ILC and LHC synergy

Measurements of the gluino, wino and bino masses

can be extrapolated by renormalization group to

high scales, and we can see if there is a grand

unification, thus telling us about the scale of

Susy breaking.

m1/2

The sfermion mass terms extrapolated to high

scale reveal the nature of the Susy breaking

shown here for Sugra and Gauge mediated symmetry

breaking.

LHC

High mass Sugra and GMSB patterns are distinctive.

m0

ILC

ILC and LHC synergy

ILC measures masses, couplings and mixings of the

accessible Susy spectrum much more precisely than

LHC. LHC can observe higher mass sparticles.

Either LHC and ILC alone gives an incomplete view

of the new physics. Acting in concert, like

binocular vision, they give a depth of view that

can tell us much more than either alone.

Pardon me, I thought you were much farther away

Supersymmetry summary

- Low mass supersymmetry offers many desireable

properties - Cures the hierarchy problem
- Provides a dark matter candidate
- Allows for unification of Strong, EM, Weak gauge

forces - Has possible sources of CP violation that could

address the baryon-antibaryon asymmetry - And Susy is an ingredient of string theories

If Susy provides these explanations, it will

surely be found at the LHC. The ILC, to the

extent that it can access the Susy particles,

will make precision measurements of masses,

quantum numbers, and couplings to tell us which

Susy breaking model is at work.