SUSY 3
Jan Kalinowski
Outline
Linear Collider: why?
Precision SUSY measurements at the ILC
masses, couplings, mixing angles, CP phases,
Towards reconstructing the fundamental theory
the SPA Convention and Project
Summary
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After discovering SUSY at LHC
Many burning questions will arise:
• is it really SUSY? (measurement of quantum numbers)
• how is it realized? (MSSM, NMSSM, …)
• how is it broken?
ILC will be indispensable to
answer these questions!
Sobloher
Make full use of the flexibility
of the machine:
- tunable energy
- polarized beams
- possibly e-e- and  collisions
200
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1000
3000
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The International Linear Collider
An intense R&D process since 1992
Huge world-wide effort to be ready for construction in 2009/10
(Global Design Effort GDE)
ICFA parameter document:
The baseline:
- e+e- LC running from MZ to 500 GeV, tunable energy
- e- /e+ polarization
- at least 500 fb-1 in the first 4 years
Upgrade: to ~ 1 TeV 500 fb-1 /year
Options :
- GigaZ (high luminosity running at MZ)
- , e, e-e- collisions
Choice of options depending on LHC+ILC physics results
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The ILC physics case
0.
Top quark at threshold
• measure its mass, verify its couplings
1. Higgs
• ‘light’ (consistent with precision EW)
 verify the Higgs mechanism is at work in all elements
• ‘heavy’ (inconsistent with precision EW)
 find out why prec. EW data are inconsistent
2. 1.+ new states (SUSY, ED, extra Z’, little H,...)
• measurements of new states: masses, couplings
• infer properties of states above kinematic limit
3. No Higgs, no new states
• find out why precision EW data are inconsistent
• look for threshold effects of strong/delayed EWSB
LHC + LC data analysed together  synergy!
(LHC/ILC study group, `Weiglein et al.)
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Masses
Two methods to obtain absolute sparticle masses:
In the continuum
At the kinematic threshold
smuons:
Martyn
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Masses
If a double cascade occurs, the intermediate state can be fully
reconstructed
e.g.
Assuming neutrino masses known to some extent
•
two LSP 4-momenta => 8 unknowns
•
4 mass relations + E,p conservation => 8 constraints
LSP momenta can be reconstructed
Berggren
4-momentum of the intermediate particle
(here slepton) can be measured!
So if you are used to think that
a sparticle is just an edge or an end-point,
change your mind – it can be a peak!
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Couplings and mixings
EW gauge and Yukawa couplings
can be probed in e.g.
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Charginos + neutralinos
Including masses and polarized cross sections for light neutralinos:
Now ask your LHC friends to look for
=> crucial test of the model
Desch, JK, Moortgat-Pick, Nojiri,
Polesello
Feeding info on m(
) back to ILC
=> improved accuracy
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Neutralino couplings
Choi, JK, Moortgat-Pick, Zerwas
also the equality of EW gauge
and Yukawa couplings can be
tested with polarized beams
In these analyses sleptons assumed to be seen at ILC and measured.
What if all sfermons heavy, like in focus-point or split SUSY?
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Heavy sfermion case
Focus-point inspired case
Desch, JK, Moortgat-Pick, Rolbiecki, Stirling
sfermions ~ 2 TeV
only stop1 ~1.1 TeV
Expectations at LHC:
•
decay dominates, but huge background from top production
• other squarks accessible, but low statistics, BG, .. => Dm=50 GeV
• large gluino production,
dilepton edge clearly seen, measure
Expectations at ILC 500 GeV
• large
production, measure its mass precisely
• very small cross section for neutralinos
•
masss from
decay + LHC
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Heavy sfermion case
FB asymmetry very sensitive
to sneutrino mass
,Z
=>
DAFB
• obtain sneutrino mass
• distinguish models
(e.g. focus point SUSY from
split SUSY)
Even a partial spectrum
can tell a lot…
Decay lepton FB asymmetry
Desch, JK, Moortgat-Pick, Rolbiecki, Stirling
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Majorana and CP of neutralinos
Can be probed in
• neutralino pair production at threshold
• neutralino decay spectrum near the end-point
• neutralino production + decay
after Fierz-ing selectron exchanges
Production:
Decay:
If CP conserved,
in non-relat. limit
(
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for production
for decay
intrinsic CP )
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Majorana and CP of neutralinos
1. Production at threshold
• if
=> P-wave
• if
=> S-wave
CPC: if (12) and (13) in S-wave
(23) must be in P-wave
otherwise CP violated
JK
2. Compare production of
(12) with decay of 2->1
CPC: if production in S-wave
decay must be in P-wave
otherwise CP violated
S.Y.Choi
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e and  options
Create HE photon beam by Compton back-scattering laser light on electrons
Ginzburg, Kotkin,
Serbo, Telnov
Photons
retain ~90% of electron beam energy
almost 100% conversion – no loss of luminosity
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e example
Assume that LSP mass=100 GeV and already measured => higher reach
in selectron mass
Illian, Monig ’05
N
signal
important SM background from
can be considerably suppressed by taking
right-handed electron beam
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 examples
1. very useful for Higgs boson studies
- higher kinematic reach
- investigate CP using polarized  beams
2. Measure tanb (for moderate to large values)
- important parameter
- notoriuosly difficult to determine
Choi, JK, Lee, Muhlleitner, Spira, Zerwas
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Cosmology connection: benchmarks
How well <sv> can be predicted from LHC/ILC depends on model for NP
American LCC + Snowmass05 benchmark points
Peskin, LCWS06
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LCC2
LHC alone allows multiple solutions
Squarks and sleptons heavy,
relevant param. M1, M2, tanb, m
measured at LHC
J. Alexander et al.
Need to know gauginohiggsino mixing angle
can be measured at ILC
ILC
resolves
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LCC2: cross-checks, predictions
With the LSP properties determined, calculate
• neutralino-proton cross section for
direct DM search experiments,
or using measured cross section
determine the flux of DM
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• rate of  from DM annihilation in
the galactic center,
or using measured rate determine
the DM density
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other LCC points
The LHC will start testing cosmology.
In some cases the LC will be invaluable.
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Towards reconstructing SUSY:
Supersymmetry particles will be discovered at the LHC
Future ILC will provide additional precision data on masses and couplings
Will everybody be happy?
We would like to know the relation of the visible sector to the fundamental theory:
 what is the origin of SUSY breaking ?
 what is the role of neutrinos ?
 is it related to the theory of early universe ?
 how to embed gravity ? etc., etc.
Probably we won’t have a direct experimental access to these questions
But SUSY is a predictive framework !
We can analyse precision data and state how well within some specific SUSY/GUT
model the relation of observable to fundamental physics can be established
You may ask: who cares about precision ??
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Remember Tycho Brache ?
from W. Kilian
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Practical questions
How precisely can we predict masses, cross sections, branching ratos,
couplings etc. ?
 many relations between sparticle masses already at tree-level, much
worse at loop-level
 no obvious choice of renormalizaton scheme
What precision can be achieved on parameters of the MSSM Lagrangian ?
 Lagrangian parameters not directly measurable
 some parameters are not directly related to one particular observable,
e.g., tanb, m
 fitting procedure, ....
Can we reconsruct the fundamental theory at high scale ?
 unification of couplings, soft masses etc.???
 which SUSY breaking mechanism ??
Goals of the SPA Project
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http://spa.desy.de/spa
The SPA project is a joint study of theorists and experimentalists working on LHC and
Linear Collider phenomenology. The study focuses on the supersymmetric extension of the
Standard Model. The main targets are
•High-precision determination of the supersymmetry Lagrange parameters at the
electroweak scale
•Extrapolation to a high scale to reconstruct the fundamental parameters and the
mechanism for supersymmetry breaking
The SPA convention and the SPA Project are described in the SPA report,
Eur.Phys.J.C46:43-60,2006
[arXiv:hep-ph/05113444].
Spiritus movens: Peter Zerwas
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The Document
More than one ‘astronomer’ involved
Please join in !!!!
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Summa summarum
Supersymmetry has been motivated as a way to stabilize the
hierarchy
At present: no sign, but not excluded either
If true, exciting times at near-future colliders
Precision measurements will be necessary to reconstruct the
theory
Once seen and studied, it may provide a telescope to physics
at GUT/Planck/string scales
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