Determination of SUSY Parameters at LHC/ILC

Hans-Ulrich MartynRWTH Aachen & DESY

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Outline

• Why and how to explore supersymmetry

• Discovery and measurements at LHC

• Precision measurements at ILC

• Reconstructing supersymmetry

• Dark matter and colliders

• Scenarios off mainstream

• Summary and outlook

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Why supersymmetry

Most attractive extension of Standard Model

• ensures naturalness of hierarchy scales

• unification of fundamental gauge forces

• provides cold dark matter candidate

• stabilisation of light Higgs mass corrections

• local SUSY incorporates gravity

• additional sources of CP violation

• maximal symmetry of fermions & bosons

EW data consistent with weak-scale SUSY

LHC experimentsoutcome extremely important, huge impact on

futureprojects - ILC, VLHC, superB, super… discovery - revolution in particle physics

Ellis et al 06

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MSSM

• Building blocks SM MSSM– duplication of particles sparticles

– 105 new parameters in MSSM R-parity conserving

• Biggest mystery - symmetry breaking invoke hidden sector

• Plethora of mediation mechanisms:gravity, gauge, gaugino, anomaly, string inspired, … reduced set of parameters– what are dominant effects producing couplings of hidden sector

and MSSM fields: tree-level, loop-induced, ..., ?

Hidden sector MSSM sectorFlavour blind

mediators

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Soft parameters

GUT scale low scale MSSM Observables

mSUGRA:m0, m1/2, A,tanβ, sign

string inspired models

GMSB

AMSB

…..

masses, decay widths,spin, couplings, mixings,quantum numbers,cross-sections

RPV, CPV, LFV …

neutralinos/charginossleptonssquarksHiggs (h,H,A)

, tanβ, Af

at present

RGEMGUT, MX, MS, HO corrections, renormalisation scheme..., ?

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Soft parameters

GUT scale low scale MSSM Observables

mSUGRA:m0, m1/2, A,tanβ, sign

string inspired models

GMSB

AMSB

…..

masses, decay widths,spin, couplings, mixings,quantum numbers,cross-sections

RPV, CPV, LFV …

neutralinos/charginossleptonssquarksHiggs (h,H,A)

, tanβ, Af

in future

all obstacles solvable with sufficient precision data -- need new techniques at hadron colliders

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Experimental facilities

LHC

• 2007 commissioning @ 0.9 TeV

• 2008 start operation @ 14 TeVgoal: few fb-1 per experiment

• 2010 reliable results on new physics, discoveries?

• huge discovery potential up to scales of m ~ 2.5 TeV

ILC

• 2006 reference design

• 2009 technical design

• 2010 + … ready for decision

• 7 - 8 years construction

• polarised e+e-, e-e-, γγ

• high-precision measurements up to kinematic limit 0.5 - 1 TeV

pp 14 TeV e+e- 1 TeV

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Exploring supersymmetry LHC

Dominant production of strongly interacting squarks, gluinos Many states produced at once,

long decay chains complicated

final states

ILCProduction of non-colored

sleptons,neutralinos, charginosSelect exclusive reactions,

bottom-upapproach, model independent

analysis

Considerable synergy between LHC and ILC

combined analyses, concurrent running

SPS 1a’ mSUGRA benchmark

favourable for LHC & ILC

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Discovering SUSY at LHC

• Signatures from gluino/squark decay chain: high pT multi-jets, isolated leptons,

large missing energy

• Inclusive search Meff=∑1,4ETi + ET

miss

QCD background reliably calculable?

W, Z, tt production Anastasiou

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Early discovery of SUSY at LHC?• Is there New Physics?

What is the scale?

Science community expects fast and reliableanswers, e.g. planning for future facilities

• Understanding detector and ETmisss

spectrum crucial!

• Discovery potential vs luminosity

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Reconstructing masses at LHC

Exploit variety of invariant mass distributions, low & high end pointsConstruct kinematic constraints on sparticle masses precise mass differences seriously limited by poor neutralino mass

Nojiri, SUSY06

strong slR - χ1 correlation

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Reconstructing masses at LHC

• End point method: waste of statistics and information

• Mass relation method: exact kinematics using complete events

• bbll channel– 5 masses: each event define 4-dim hypersurface in 5-dim mass space

– 5 events sufficient to solve mass equations

– many events: overconstraint fit, solve for masses, improved resolution

• All sparticle masses known: reconstruction LSP momentum

Kawagoe, Nojiri, Polesello 2004

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Spin, L/R sfermion?• Shape of decay distribution carry spin information

• Problems: pick up correct combinationquark + near lepton, tell ql+ from anti-ql+

• Solution: lepton charge asymmetry

• Assumptions: more squarks than antisquarkssquarks/sleptons dominantly left or right neutralino spin ½

• Distinct from other models, e.g. UED

spinless

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Finding sparticles with help of ILC

• Light neutralinos and chargino found at ILC

Prediction of masses of heavy neutralinos and charginomay not be accessible at ILC

• New particle can be identified at LHC via‘edge’ in the di-lepton mass spectrum

~0

4

~0

2

LHC/ILC interplay: Phys.Rept.426 (2006) 47

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SPS 1a’ spectrum from LHC

LHC analysis

• access to high mass states, sleptons and gauginos via cascades

• resolution limited by strong correlations with neutralino LSP

• mass differences much more accurate

Correct interpretation?

neutralino

sneutrino

KK photonAguilar-Saavedra et al

2006

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Masses at ILC

• Energy spectrum, end points

δm ~ 0.1 GeV

• Threshold excitation curvecharacteristic β dependence, steep rise

δm ~ 0.05 - 0.2 GeV

flat energy spectrum

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Masses -stau

Stau production

flat energy spectrum distorted to triangular shapefit upper end point mstau

• Coannihilation regionsmall Δm = mstau-mχ 3 GeV accessible

difficult measurement due to huge γγ bkgimportant to get DM constraint

very problematic for LHC

mstau = 173 GeV

δm ~ 0.3 GeV

Point D’

mstau = 218 GeV

Δm = 5 GeV

δm ~ 0.15 GeV h-um

04

E+E-

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Masses - gauginos

Neutralino production

Chargino production

Many reactions to get the mass of the lightestneutralino very accurately! δm ~ 0.05

GeV

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Masses - cascade decays

Decay chains à la LHC

kinematics of cascade decay provides access to intermediate slepton2-fold ambiguity for mass solutions

extremely narrow mass peak δm/m ~ 5∙10-5

Similarly: selectron reconstruction

Berggren 05

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Masses & mixings

Chargino sector

Mass matrix

masses from threshold excitation

Mixings

polarised cross sections σL,R[11] and σL,R[12]

disentangle ambiguities and determinemixing angles cos 2ΦLRChoi et al

2000

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Masses & mixings

Stop production

lightest squark in many scenarios, difficult todetect at LHC

Mixing

polarised cross sections

Minimal mass reconstructed from kinematics, momentumcorrelations, using mχ

peak at mstop Finch et al 04

SPS 5

Bartl et al 97

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Spin

Threshold productionand

Angular distribution

all masses known: reconstructionpolar angle Θ (2-fold ambiguity)

Unambiguous spin assignmentmodel inependent, distinct from e.g. UED

L/R quantum numbers via polarisationR sfermions prefer right-handed electrons e-

R

L sfermions prefer left-handed electrons e-L

Choi et al 2006

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Couplings

Basic element of SUSYidentical gauge and Yukawa

couplingsSU(2) gauge g = Yukawa ĝ U(1) gauge g’ = Yukawa ĝ’

Slepton production

Freitas et al, 04

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SPS 1a’ spectrum from LHC+ILC

Coherent LHC+ILC analysis

• complementaryspectrum completed

• superior to sum of individual analyses

• accuracy increased by 1-2 orders of magnitude

Challenge:experimental accuracy matched by theory?

Aguilar-Saavedra et al 2006

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How to proceed?

• We want to understand the relation between the visible sector, observables, and the fundamental theory

SUSY provides a predictive framework

• How precise can we predict masses, x-sections, branching ratios, couplings, … ?– many relations between sparticle masses at tree-level, much worse at loop-level

– choice of renormalisation scheme?

• Which precision can be achieved on parameters of the MSSM Lagrangian?

– Lagrangian parameters not directly measurable

– parameters not always directly related to a particular observable, e.g. µ,tan ß

– fitting procedure, …

• Can we reconsruct the fundamental theory at high scale?

– unification of couplings, soft masses, … ?

– which SUSY breaking mechanism, origin of SUSY breaking?

Goals of the SPA Project

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SPA convention and project

• Supersymmetry Parameter AnalysisSupported by ~100 theorists & experimentalists

• SPA Convention

renormalisation schemes / LE parameters / observables

• Program repository

theor. & expt. analyses / LHC+ILC tools / Susy Les Houches Accord

scheme translation, RGE & spectrum calculators, event generators, fitting, …

• Theoretical and experimental tasks

short- and long-term sub-projects, SUSY calc. vs expt., LO NLO NNLO, …, new channels & observables, combine LHC+ILC data

• Reference point SPS 1a’

derivative of SPS 1a, consistent with all LE and cosmological data • Future developments

CP-MSSM, NMSSM, RpV, effective string theory, etc.

You are invited to join! http://spa.desy.de/spa/ EPJC 46 (2006) 43

Hollik, Robens

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Extracting Lagrange parameters

Global fit of all available ‘data’ to most up-to-date HO calculationsinput: masses, edges, x-sects, BRs from LHC & ILC

~120 values incl. realistic error correlationstheory: no errors (no reliable estimate available)

output: ~20 parameters

tools Fittino (Bechtle, Desch, Wienemann), SFitter (Lafaye, Plehn, D. Zerwas)

Results SPS 1a’ high precision

LHC alone not able to constrain

most parameters Arkani-Hamed

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High-scale extrapolation

• Gauge couplings α-1

grand unification ~2σ / giU~2% ε3 at ~8σ level

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High-scale extrapolation

• Universality of gaugino & scalar mass parameters in mSUGRA

• Evolution in GMSB distinctly different from mSUGRA

• Bottom-up evolution of Lagrange parameters provides high sensitivity to SUSY breaking schemes

Q [GeV] Q [GeV]

1/Mi[GeV-1] Mj2 [103 GeV2]

mSUGRA

Q [GeV]

Mj2 [103 GeV2]

GMSB

MM

Porod

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Testing mSUGRA

mSUGRA fit excellentUniversality can be tested in bottom-up approach

non-coloured sector at permil to percent levelcolored sector needs improvement

LHC+ILC: Telescope to Planck scale physics

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metastable stau

Dark matter & colliders

Cold dark matter in Universe ΩDM≈ 22%

ΩDMh2 = 0.105 ± 0.008 WMAP

Understanding nature of cold dark matter requires

• direct detection DM particle in astrophysical expt

• precise measurement of DM particle mass & spin at colliders

• compare relic density calculation with observation Ωχ h2~ 3 ∙10-27cm3s-1/<σv>

requires typical weak interaction annihilation cross section

Candidates: neutralino, gravitino, sneutrino, axino, …Formation: freeze out of thermal equilibrium

in general Ωχ » 0.2, annihilation mechanism needed

thermal production

late decays Kraml, Allanach

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Neutralino dark matter

SPS 1a’ ‘bulk region’

annihilation through slepton exchange

χχ тт, bbσχχ depends on light slepton masses & couplings

LHC: precision ~20% (very high lumi)

assuming mSUGRA, ‘a posteriori’ estimate/fix of unconstrained parameters, e.g. mixings

LHC + ILC: precision ~1-2%

matches WMAP/Planck expts Reliable prediction for direct neutralino -

proton detection cross section

Baltz 06

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Neutralino dark matter

LCC2 ‘focus point region’

heavy sfermions, light gauginos

annihilation ΧΧ WW, ZZ

σχχ depends on M1, M2, μ, tanβ

LHC: study gluino decays, not enough constraints to solve neutralino matrix

LHC + ILC: ~10% precision on relic abundance

ILCresolves

LHC multiple solutions

bino

wino

Higgsino

M1

μ

parasitic LHC peak at Ωχ ~ 0

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Gravitino dark matterGravitino mass set by SUSY breaking scale F of mediating

interaction m3/2 =F/√3∙MP Planck scale MP =2.4∙1018 GeV

In general free parameter depending on scenariosupergravity, gaugino, gauge mediationm3/2 = TeV … eV

Most interesting: gravitino LSP, stau NLSP m3/2 = few GeV - few 100 GeV

Dominant decay gravitational coupling, lifetime sec - years

Gravitino not detectable in astrophysical expts

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Gravitino dark matter

Detecting metastable staus & gravitinosidentify & record stopping stau stau mass

wait until decay stau lifetimemeasure τ recoil spectra gravitino mass

rare radiative decays gravitino spin γ- τ correlations in

LHC detectors not appropriate stau mass ok, no lifetime or decay spectramoderate rate, high background, busy timing

external absorber/calorimeter needed

ILC ideal environmenthigh rate, adjustable via cms energy

low duty cycle ~0.5%, excellent calorimetry

Hamaguchi et al 04, Feng, Smith 04, DeRoeck et al 05, H-UM 06

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trap

Gravitino dark matter GDM ε scenario mo=m3/2=20 GeV, M1/2=440 GeV

ILC case study L=100 fb-1 @ 500 GeV (<1 year data taking)

• Prolific stau production

• Lifetime measurement

• Decay spectrum

Access to Planck scale / Newton’s constant

• SUSY breaking scale

• Unique test of supergravity:gravitino = superpartner of graviton

H-U M, EPJC 48 (2006) 15

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Off mainstream scenarios

• Scenario SPS 1a’ is just a benchmark, a test bed

• Nature may be very different from SPS 1a’, mSUGRA, or …

• Other possibilities– complex parameters, CP phases baryogenesis

– lepton flavour violation neutrino masses

– R-parity violation unstable LSP, neutrino masses

– alternative SUSY breaking mediation anomaly, gauge, gaugino, …

mixed scenarios of SUSY breaking

– additional matter/gauge fields NMSSM, UMSSM, ESSM, …

– additional dimensions

– split SUSY

– and many more …

• Different signatures at LHC / ILC

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CP phases

CPV in SUSY may explain baryon asymmetryCP phases

affect CP-even quantities

generate CP-odd observables (triple products)

EDM constraints for 1st, 2nd generation sfermionsand charginos/neutralinos mSUGRA Φμ < 0.1-0.2

Stop decay widths μ, At

strong phase dependence Φ(At) of stop chargino + b

Neutralino sector in selectron production μ, M1

pure Χi0 exchange in t and u channel

transversely polarised e-e- beams

cross section CP even

azimuthal asymmetry CP odd pse_L∙(se1x se2)

complementary to

SPS 1a

S/√L

Bartl et al

Kernreiter, Rolbiecki

2 σ @ L=100 fb-

1

m=380 GeV

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Lepton Flavour Violation

LFV in slepton pair production

Seesaw mechanism to generate neutrino masses mν

LR extension: νR singlet fields and superpartners

added to MSSMsensitivity σLFV ~ 0.1-1 fb

Majorana mass scale MR~1013-1014 GeV

radiative decay Br(μeγ)~10-13

Massive neutrinos affect RGEs of sleptonsflavour off-diagonal terms with large Yukawacouplings for 3rd generationkink in evolution of L3, H2

M(νR3) = (5.9±1.6) 1014 GeV

μe τμ

SPS 1a

Deppisch et al 04

Blair et al 05

Deppisch

SPS 1a’

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Split SUSY

SUSY breaking scale split between scalar & gaugino sectors

Spectrumlight Higgs, neutralinos, charginos, gluino squarks, sleptons, H, A extremely heavy

Signatures strongly dependent on gluino lifetime

long-lived gluino, R-hadrons LHCdisplaced vertices

stable R0 missing ET

stable R+ balanced pT

Chargino/neutralino sector LHC & ILCconventional phenomenology for searches/massesanomalous Yukawa couplings from gaugino-Higgsino mixing

Both LHC & ILC needed to establish SUSY Lagrangianat common scalar mass scale m˜

Arkani-Hamed, Dimopoulos

Kilian et al 04

Provenza

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Summary & outlook

Experiments at LHC will tell if weak-scale supersymmetry isrealised in nature

Methods and techniques have been developed to discover andexplore supersymmetry. Close contacts between experiment andtheory are needed to go beyond basic discovery

SPA project provides a platform for discussions

Both accelerators, the LHC and a future ILC, are necessary tounderstand the sparticle spectrum in detail and to unravel in amodel-independent way the fundamental supersymmetry theory

High-precision measurements of low-energy Lagrange parameters

offer the unique possibility to perform reliable extrapolationstowards the GUT / Planck scale and to test the concepts ofunification of the laws of physics