1. Supersymmetry at LHC and beyond
---Ultimate tagets---
Mihoko M. Nojiri
YITP, Kyoto University

2. Why collider ?? Best way to 1. See existence of superpartners
2. Supersymmetric relations
3. Soft mass measurements
Understand SUSY breaking mechanism
] Interactions at high scale
Impacts on the other physics
B, LFV, Dark matter

3. 1. The existence scaler mass We should try to extract
Large cross section.
No SM backgrounds
Search up to 2TeV squark or
gluino.
1000 events/year
for 1TeV squarks and gluinos
We should try to extract
ALL physics information
from THIS experiment!
gaugino mass
(Not only) famous SPS1a …
scaler mass

4. 2. Supersymmetric relations (I can’t wait until LC operation)
chiral nature
No new dimensionless coupling
Fermion-sfermion-gaugino(higgsinocoupling)

5. chirality and m(jl) distributions Richardson (2001), Barr(2004), Kawagoe Goto Nojiri(2004)
Chirality of slepton appears in m(jl) distribution
Right handed lepton goes same direction to the jet direction
Right handed anti-lepton goes opposite to jet
Charge asymmetry!

6. MC simulations (left and right sleptons)
Kawagoe, Goto, Nojiri(2004)

7. smuon L-R mixing(Goto’s talk)
tanb
Br(e)
Br(m)/Br(e)
A(m) 10
6.3%
1.04
0.93 15
2.4%
1.09
0.83 20
1.2%
1.17
0.70
visible in wide parameter regions
Proof of smuon F term mixing
Other examples?( m(bb) distribution of gluino->stop top)
Hisano, Kawagoe,MMN 2003

8. 3.Soft mass measurement Collider signature of SUSY “easy” to “hard”
Long lived NLSP(~O(10m))
Neutral LSP
sfermion<gaugino
gaugino<sfermion
gaugino<<sfermion
degenerated
Too heavy
Models
Gauge mediation
Supergravity and the variants
M>m
M~m
M<<m KK

9. “Easy case” Signature with long lived NLSP
Shorter life time (<O(1cm))
lots of leptons and photons
endpoint analysis.
Charged Long Lived NLSP
TOF for charged track
Dt~1ns at 10m-20m
Full reconstruction
Neutral Long Lived NLSP
No track
Fine time resolution at ECAL cDt~3cm at O(1m)
Gravitino momentum and decay position can be solved with the time info
(Kobayasi, Kawagoe, Ochi,MMN(2003)
Kawagoe’s talk)
No systematic study yet.
Hinchliffe and Paige

10. “Moderate cases” Long lived NLSP(~O(10m)) Neutral LSP Too heavy
sfermion<gaugino(2 body)
gaugino<sfermion(3 body )
gaugino<<sfermion
degenerated
Too heavy
Time delay Signals
TOF for charged track
Arrival time(photon)
Endpoint analysis(Giacomo’s talk)
Lepton mode
Tau and b modes
Jet selection
No good ideas

11. Summary of endpoint study at SPS1a
Based on the endpoint analysis, sparticle
masses may be understood very well. The lepton channels are important.
LSP mass [dark matter mass
Slepton mass, neutralino mass [Dark matter density

12. Limitations of the end point method
unkonwn LSP momentum
No kinematical constraint even though you know the masses
Waste of statistics
Events off the end points are not used.
Need statistics enough to see the end point.
signals from different cascades to make a single broad end point.

13. Mass relation method apply mass-shell constraints to solve events
Full event reconstructions! we see peaks.
Use all events for mass and distribution study.
“In principle”, a few events are enough to determine the masses and LSP momentum (up to jet energy resolutions)
Kinematical constraints available.
Nojiri, Polesello, Tovey hep-ph/ (Les Houches)

14. Example of mass relation method
5 Dim mass space M
A event<-> 4 dim hypersurface
in M
gluino mass
For simplicity Assume we know mass of
sbottom mass
Each event corresponds to a curve in the mass plane
Two events is enough to give the masses, and
LSP momentum.
a distribution of the solution in the previous plot

15. Sbottom mass determination (plot lighter solution for fixed gluno mass)
tanb=10
Background level
tanb=20
tanb=15
1/3
1/2
485(52)GeV
492(525)GeV
Sbottom2 contribution
479(532)GeV
Kawagoe, MMN, Polesello…

16. mSUGRA and 3rd generation mass spectrum
FCNC constraints are weak for 3rd generation.
　　non-universal squark and slepton masses for the 3rd generation.
Yukawa RGE running breaks the universality at at the GUT scale.
m(stop,sbottom)<m(1st)
Left-right squark mixing
SPS1a tanb=10 sbottom mass 492GeV
tanb= GeV
Implication to higgs mass, B physics….

17. A event a probability density for true masses(L)
log L(1) logL(2) log L(3) logL(4)
= log L(~Dc2)
tanb=10
tanb=20

19. Spin off from the mass relation method
Neutralino momentum also solved.
Transverse momentum
of the 2nd LSP
For the 2nd LSP, transverse
Momentum is known
a event Corresponds to 1 dim line in the
mass space.
Even shorter cascade can be solved.
2nd LSP
Total missing
momentum
reconstructed LSP
momentum

20. New channels using missing pT (hep-ph/0312317,18)
Example I
chargino reconstruction
Example II heavy higgs reconstruction 4lepton channel .

21. “getting more difficult”
Large tanb
gaugino<sfermion
squark->gluino jets
Then 3 body
Losing statistics
Tau mode dominate.
(giacomo’s talk)
All squarks decays into gluino, information loss
Jet selection? B modes?
Degenerated (no hard jets…)

22. Handle signal without leptons
Sometimes SUSY signature is not hard leptons.
Still stop, sbottom may be lighter than other sparticles
due to top Yukawa RGE
SUSY -> events with many b jets.
Gluino decays dominantly into
btc- ,bbc0 and ttc0
b tagging efficiency is 60%
Looking for non-b jets from SUSY decay is difficult.
many QCD jets

23. Reconstructing top from gluino decays
t a bW a bjj
N(jet) a7 typically. Many BG
to W a jj
Background to t abWabjj is estimated from events in the
sideband
mjj<mW-15GeV
mjj>mW+15 GeV.
Reconstructed top quarks are used to study tb distribution .

24. Difference between two body and three body
Branching ratio is biggest for tb final state.
SPS1a: edge with DMtb ~4GeV for 100fb-1
SPS2 :(focus points M=300GeV), distribution may reflect
But cross section is small….
(from the plots in
Hisano, Kawagoe, Nojiri PRD )
1000 fb-1 but cut is not optimized

25. Conclusions LHC starts soon ! (2007, I hope!)
SUSY is polarized. m(jl) distribution is
easy to study. Want more example. Jet charge
tagging????
New “full reconstruction” technique. It works even for small statistics.
Note: If event contains many neutrinos, the method cannot be applied. Go back to the end points?
How to combine end points and “full reconstructions”
We need more thoughts and works. “Crazy theorists” are especially welcome.

26. And more .. Interplay between LC andLHC

27. LHC: gluino and two sbottom masses
For the wino like second –lightest neutralino
If WEAK SUSY parameters are known
precisely enough, decay pattern of sbottom
may be understood as
the function of q.
Hisano, Kawagoe, Nojiri (for LHC/LC)

28. Precise SUSY with LHC/LC
LC can change “silver” to “gold”
Interaction measurements
Checking universality O(1)%
O(10%) for GUT scale scalar masses.
Need more precise estimation of running from GUT to weak scale
Fix low energy parameters for DM, Higgs, B, LFV. Ex. O(1%) thermal relic density