Transcript Searches for Supersymmetry at the Tevatron

Searches for
Supersymmetry at the
Tevatron
looking for chargino and
neutralino
Cambridge HEP Seminar
Friday 5th May 2006
Giulia Manca,
University of Liverpool
“Supersymmetry”,
by Karl Hager
From the artist’s
website:
“…I try to leave the
intention minimized
while maintaining an
element of exploratory
desperation.”
http://www.cassetteradio.com/cubagallery/hagen.htm
2
Outline
• Supersymmetry
• The Tevatron and its
•
•
•
experiments
Searching for Chargino
and Neutralino
Conclusions
Outlook
5th May 2006
Giulia Manca, University of Liverpool
3
Supersymmetry: All you need to
know
Extends the Standard Model (SM) by predicting a new symmetry:
spin-1/2 matter particles (fermions) <=> spin-1 force carriers (bosons)
Standard Model Particles
Susy Particles
g
Higgsino
Higgs
Higgs
e  
e


~
G~
G
Gravitino
G
Graviton
Quarks
5th May 2006
Leptons
Force particles
Squarks
Sleptons
Susy
Force particles
Giulia Manca, University of Liverpool
4
Supersymmetry: All you need to
know
Extends the Standard Model (SM) by predicting a new symmetry:
spin-1/2 matter particles (fermions) <=> spin-1 force carriers (bosons)
Standard Model Particles
Susy Particles
g
Higgsino
Higgs
Higgs
e  
e


~
G~
G
Gravitino
G
Graviton
Quarks
5th May 2006
Leptons
Force particles
Squarks
Sleptons
Susy
Force particles
Giulia Manca, University of Liverpool
5
Supersymmetry: All you need to
know
Extends the Standard Model (SM) by predicting a new
symmetry:
spin-1/2 matter particles (fermions) <=> spin-1 force carriers (bosons)
Standard Model Particles
Susy Particles
g
Higgsino
~0
Higgs
Higgs
ci
e  
e


4 neutralinos
~c
i
2
~ charginos
G~
G
Gravitino
G
Graviton
Quarks
Leptons
Force particles
Squarks
Sleptons
New Quantum Number R-Parity  Rp  (1)BL2s
Lightest Sparticle (LSP) stable!
5th May 2006
Susy
Force particles
+1 (SM particles)
-1 (Susy particles)
Giulia Manca, University of Liverpool
6
•
Supersymmetry: models
Different mechanisms of susy breaking lead to different models
Model
MSSM
Name
Breaking mechanism
and scale
Minimal
Supersymmetric
Standard Model
Parameters
LSP
>100
any…
mSugra, Minimal
cMSSM Supergravity
Constrained MSSM
Gravity (GUT)
M0,M1/2,
A0,tan
sgnor
c0 
GMSB
Gauge Mediated
Symmetry
Breaking
Gauge messengers
(10 TeV)
m,Mm, tan,
N5, sgn(),
Cgrav
Graviti
no (G)
AMSB
Anomaly Mediated
Symmetry
Breaking
“conformal anomaly”
M3/2,m0,tan
sgn
c0 
If RP not conserved, LSP decays into SM particles (RPV models)
5th May 2006
Giulia Manca, University of Liverpool
7
Supersymmetry: All you need to
know
Extends the Standard Model (SM) by predicting a new symmetry:
spin-1/2 matter particles (fermions) <=> spin-1 force carriers (bosons)
Standard Model Particles
Susy Particles
g
Higgsino
~0
Higgs
Higgs
ci
e  
e

4 neutralinos

~c
i
2
~ charginos
G~
G
Gravitino
G
Graviton
Leptons
Quarks
Force particles
Squarks
~
Sleptons
Susy
Force particles
1. mSugra and AMSB: c0 LSP, stable
~
2. GMSB: G LSP,stable
3.
Rp 2006
(RPV): LSP decays into SM particles
5th May
Giulia Manca, University of Liverpool
8
Supersymmetry: why ?
•Solves “Hierarchy Problem”
•Provides Grand Unification
Standard Model
SUSY
Theory at the 1016 GeV scale
•Consistent with results from
Precision Data fits
New
Top
Mass
172.5
GeV/c2
5th May 2006
•Rp Conserving models
provide good Dark Matter
Candidate (LSP)
Giulia Manca, University of Liverpool
9
•
Supersymmetry & Dark Matter
Evidence for Dark Matter
 galaxy rotation
 fluctuations in the cosmic
In mSugra and with Rp
conserved and EW radiative
corrections,
 5 main regions where neutralino
fulfills the WMAP relic density
•bulk region (low m0 and m1/2)
•stau coannihilation region mc  mstau
Common gaugino mass M1/2
•
microwave background (WMAP)
From WMAP: CDMh2 ≤ 0.113
•hyperbolic branch/focus point (m0 >> m1/2)
•funnel region (mA,H  2mc)
•Higgs pole: 2mc0mh
5th May 2006
Tevatron sensitive to the BULK
region in WMAP data
Common
scalar
Mof0 Liverpool
Giulia
Manca,mass
University
10
•
Supersymmetry & Dark Matter
HOWEVER: MORE OPTIONS
WITH LESS CONSTRAINED
MODELS
Evidence for Dark Matter
 galaxy rotation
 fluctuations in the cosmic
•
H. Baer, A. Belyaev, T.
Krupovnickas, J. O’Farrill,
JCAP 0408:005,2004
microwave background
(WMAP)
In mSugra and with Rp
conserved and EW radiative
corrections,
 4 main regions where
neutralino fulfills the
WMAP relic density
M1/
2
•bulk region (low m0 and m1/2)
•stau coannihilation region mc  mstau
•hyperbolic branch/focus point (m0 >> m1/2)
•funnel region (mA,H  2mc)
5th May 2006
M0
Giulia Manca, University of Liverpool
11
Supersymmetry: how ?
Wide range of signatures: look for SuSy specific signatures or
excess in SM ones; examples:
Rp
:
LSP Large Missing Energy ET
:
Isolated leptons
c0
˜ g˜ Multijets
qc±
GMSB:
2 LSPs Diphotons
1012
Remember :
VERY SMALL cross sections !!
5th May 2006
(fb)
104
10
Giulia Manca, University of Liverpool
12
The Tevatron
•
p p at ECM 1.96 TeV
•
High Luminosity
 Tevatron ~1.5 fb-1!
CDF and D0 running at
high efficiency
Still long way to go!
design goal
We are
here
Mar01-Aug05
750 pb-1
5th May 2006
base goal
Giulia Manca, University of Liverpool
Charginos and Neutralinos
14
Why Charginos and Neutralinos ?
• They are light (~ 100-500 GeV/c2)
Squarks and gluinos too heavy for the Tevatron
mSugra
GUT
scale
EW
scale
hep-ph/9311269
5th May 2006
Giulia Manca, University of Liverpool
15
Why Charginos and Neutralinos ?
• They are light (~ 100-500 GeV/c2)
Squarks and gluinos too heavy for the Tevatron
• They decay giving striking signatures
In mSugra : 3 isolated leptons + /
ET
In GMSB : 2 photons +/
ET
In AMSB : long-lived particles
In R
/p models : >3 leptons
(and many more signatures in each model
depending on the parameters !)
5th May 2006
Giulia Manca, University of Liverpool
16
The trilepton signal
Higgsinos and
gauginos mix
CHARGINOS
NEUTRALINOS


Striking signature at Hadron Collider,
THREE LEPTONS
In mSUGRA Rp conserved scenario,
LARGE MISSING TRANSVERSE
ENERGY from the stable LSP+
 Low background
 Easy to trigger
~
c 10
~
c 1
p
p
~
c 20

~
c 10

GOLDEN SIGNAL AT THE
LOW MODEL DEPENDENCE TEVATRON !!
5th May 2006
Giulia Manca, University of Liverpool
17
mSugra Existing Limits : LEP
c0 c±0GeV/c2;
c00GeV/c2;
SM Higgs Limits
Slepton Limits
Chargino-Limits
LEP I Precision measurements
Theoretically forbidden
(i.e. M1(GUT)=M2(GUT)=M3(GUT)=m1/2)
5th May 2006
Giulia Manca, University of Liverpool
Chargino-Neutralino
production…
18
 Low cross section
(weakly produced)
T. Plehn, PROSPINO
10
q
SUSY (pb) vs sparticle
mass(GeV/c2) for
√s=1.96 TeV
~
c 20
W*
1
~
c 1
q
t-channel
interferes
destructively
5th May 2006
c0 c±
~
q
~
q
q'
10-1
c 20
~
c

1
10-2
10-3
100 150 200 250 300 350 400 450 500
Giulia Manca, University of Liverpool
19
…and decay
Leptons of 1st, 2nd
generation
are preferred
~
c
~
c

1
0
1

Chargino Decay
W*

Leptons of 3rd
generation
are preferred

~
c 1

~

~
c 10

~
c 1

~
Neutralino
Decay

~
c 10
~
c 10

~
c 20
5th May 2006
~
0
 c2
Z*


~

~
c 10
Best reach for the Tevatron
for mass sleptons~mass chargino
=> BR (3ℓ) enhanced
Giulia Manca, University of Liverpool
Trileptons at CDF
21
How to investigate the different scenarios?
CHANNEL
LUM
TRIGGER PATH
 + e/
750
High pT Single Lepton
ee + e/
350
High pT Single Lepton
 + e/
312
Low pT Dilepton
e + e/
Ongoing
Low pT Dilepton
e + e/
Ongoing
High pT Single Lepton
High tan
e/e + track
Ongoing
Low pT Dilepton
region
ee + track
610
Low pT Dilepton
ee,e, 
710
High pT Single Lepton
Low tan
region
Acceptance
improvement
sensitive
to leptonic 
decay
sensitive
to all 
decays
Low tan scenario tan=5 , 38%
High tan scenario tan=20, 100%
High pT data-sample benchmark
to understand low pT data-sample
5th May 2006
Giulia Manca, University of Liverpool
22
How to investigate the different scenarios?
CHANNEL
LUM
TRIGGER PATH
 + e/
750
High pT Single Lepton
ee + e/
350
High pT Single Lepton
 + e/
310
Low pT Dilepton
e + e/
Ongoing
Low pT Dilepton
e + e/
Ongoing
High pT Single Lepton
High tan
e/e + track
Ongoing
Low pT Dilepton
region
ee + track
610
Low pT Dilepton
ee,e, 
705
High pT Single Lepton
Low tan
region
Acceptance
improvement
sensitive
to leptonic 
decay
sensitive
to all 
decays
Low tan scenario tan=5 , 38%
High tan scenario tan=20, 100%
High pT data-sample benchmark
to understand low pT data-sample
5th May 2006
Giulia Manca, University of Liverpool
23
Finding SUSY at CDF
CENTRAL REGION
=0
=1
Muon system
e
Recover loss in
acceptance due
to cracks in the
detector if we
accept muons
with no hits in
the Muon
Chamber

Drift chamber


Missing Transverse Energy
(MET)
Real MET
 Particles escaping detection
Em
Calorimeter
5th May 2006
Fake MET
Had Calorimeter
Muon pT or jet ET mismeasurement
Additional interactions
Cosmic ray muons
Mismeasurement of the vertex
Giulia Manca, University of Liverpool
24
Event kinematic
Leading lepton
Next-To-Leading lepton
Third lepton
0
0
 pT  m  m( c 2 )  m( c1 )
Chargino and Neutralino
Lepton pT (GeV)
Typical SUSY leptons
Lepton pT thresholds
EWK range
 high-pt analyses 20,8(10),5 GeV
prompt decay
Leptons
separated in space
 low-pt analyses 15(5),5,4(5) GeV
5th May 2006
Giulia Manca, University of Liverpool
25
Analysis Strategy
COUNTING EXPERIMENT
• Optimise selection criteria for best
signal/background value;
• Apply selection criteria to the data
•
Define the signal region and keep it
blind
Test agreement observed vs.
expected number of events in
orthogonal regions (“control
regions”)
•
•Look in the signal region and
count number of SUSY events !!
Or set limit on the model
5th May 2006
Giulia Manca, University of Liverpool
Backgrounds:
how
to
reduce
Backgrounds
them?
• DIBOSON (WZ,ZZ) PRODUCTION
• DRELL YAN PRODUCTION +
26
additional lepton
 Leptons have high pT
 Leptons have mainly high pT
 Leptons are isolated and separated
 Small MET
 MET due to neutrinos
e
 Low jet activity
The third lepton
originates from g
conversion
p

5th May 2006
• HEAVY FLAVOUR PRODUCTION
e
p
e
The third lepton is
a fake lepton
e
g
p
irreducible background
 Leptons mainly have low pT

e
 Leptons are not isolated
 MET due to neutrinos
0

p
p
p


Giulia Manca, University of Liverpool
27
Selection criteria: (I) Mass
Rejection of J/,  and Z
Dimuon events
Dimuon Mass(GeV/c2)
 M<76 GeV & M >106 GeV

M> 15 (20,25) GeV
 min M < 60 GeV
5th May 2006
(dielectron+track analysis)
Giulia Manca, University of Liverpool
28
(II) DeltaPhi( , ) + Jet Veto
Rejection of DY and high jet
multiplicity processes
Analysis
Kinematic
Variable
Kinematic
Cut
Trilepton
analyses
Jet ET > 20
GeV
n. Jets < 2
Dielectron +
track analysis
HT= ∑jetETj
HT < 80 GeV
5th May 2006
Giulia Manca, University of Liverpool
29
(III) MET selection
Further reducing DY by MET > 15 GeV
…Still BLIND !
5th May 2006
Giulia Manca, University of Liverpool
31
Understanding of the Data
-like sign
L=704 pb-1
MET
Each CONTROL REGION is investigated
 with different jet multiplicity-check NLO processes
 with 2 leptons requirement - gain in statistics
 with 3 leptons requirement - signal like topology
??
EWK
Diboson
low DY
Zmass
L=704 pb-1
10
15
SIGNAL
REGION
DY + g
15
5th May 2006
Z + fake
76
Invariant Mass
106
Very good agreement between SM prediction
observed
Giulia and
Manca,
University data
of Liverpool
32
Systematic uncertainty
Major systematic uncertainties affecting the
measured number of events
ee+lepton (high-pt)
 Signal
 Lepton ID 5%
Z->ee MC
 Muon pT resolution 7%
 Background
 Fake lepton estimate method 5%
 Jet Energy Scale 22%
 Common to both signal and background
 Luminosity 6%
 Theoretical Cross Section 6.5-7%
 PDFs 7%
5th May 2006
Giulia Manca, University of Liverpool
33
Results !
Look at the “SIGNAL” region
Analysis
Total
predicted
background
Example
SUSY
Signal
Observed
data
ee,e,

6.801.00
3.180.33
9
 +e/
(low-pT)
0.130.03
0.170.04
0
ee+track
0.480.07
0.360.27
1
ee + e/
0.170.05
0.490.06
0
 +e/
0.640.18
1.610.22
1
e +e/
0.780.15
1.010.07
0
5th May 2006
Giulia Manca, University of Liverpool
34
Highest lepton-pt event
In the ee like-sign analysis, we observe one interesting event
e- : 103 GeV
Mass OS1
220 GeV/c2
Mass OS2
12 GeV/c2
MET : 25 GeV
e+ : 5 GeV
e- : 107 GeV
g : 15 GeV
5th May 2006
Giulia Manca, University of Liverpool
35
Limit
No SUSY :(
•Combined all analyses to
obtain a limit on the mass
of the chargino in mSugralike scenario with no
slepton mixing
• Observed limit:
M(c1) ~ 127 GeV/c2
xBR ~ 0.25 pb
• Sensitive up to masses
M(c1) ~ 140
2
GeV/c
xBR ~ 0.2 pb
Better than LEP and Tevatron Run I ! But…
5th May 2006
Giulia Manca, University of Liverpool
36
Limit
..we are model dependent
In “standard” mSugra
Sensitive to chargino
masses of ~ 116 GeV/c2
Not able to exclude this
particular region of
parameter space with
these results …
5th May 2006
Giulia Manca, University of Liverpool
Trileptons at DO
38
DO detector
•Coverage to muons up to eta~2
=0
=1.0
=2.0
=1.0
=3.0
=3.6
5th May 2006
Giulia Manca, University of Liverpool
39
Chargino and Neutralino in 3+ET
In mSUGRA:3 leptons+ET
 Luminosity ~350 pb-1
 Use tau leptons
6 analyses:
-2l(l=e,,)+isolated track or 

ET and topological cuts (M,f, MT)
Selection
SM expected
OBSERVED
ee+t
0.21±0.12
0
et
0.31±0.13
0
t
1.75±0.57
2
±±
0.64±0.38
1
e+t
0.58±0.14
0
+t
0.36±0.13
1
SUM
3.85±0.75
4
5th May 2006
M(e (GeV/c2)
Giulia Manca, University of Liverpool
40
Chargino Neutralino Limits
mSUGRA: M(c±)≈M(c02) ≈2M(c01)
“3l-max”
•
•
M(  ) > M(c02)
No slepton mixing
Limits :
 xBR < 0.2 pb
 M(c±1)>116 GeV/c2
mSugra
optimistic
scenario
A0=0
“Heavy Squarks”
M(c±)≈M(c02)3M(q)
 xBR < 0.2 pb
 M(c±1)>128 GeV/c2
•
“Large m0”
M()>>M(c02 ,c±)
 No sensitivity
•
5th May 2006
Analyses being updated with 1 fb-1
Giulia Manca, University of Liverpool
41
Summary and Outlook:
Chargino and Neutralino in mSugra
TRILEPTONS SIGNAL:
• CDF and D0 analysed first half of data and observed no excess :(
• Set limit already beyond LEP results ! (although model dependent )
• 1.5 fb-1 of data collected and ready to be analysed
• With 4-8 fb-1 by the end of RunII we should be sensitive to Chargino
masses up to ~250 GeV and xBR ~ 0.05-0.01 pb !!
Ellis, Heinemeyer, Olive, Weiglein,
hep-ph\0411216
now
Favoured
by EW
precision
data
5th May 2006
Giulia Manca, University of Liverpool
42
The most favoured masses in
mSugra
Simultaneous variations of M0, M1/2,tan
constraining mtop,mb s and using input
measurements of b->sg, (g-2),DMh2,
get the most probable mSugra spectrum
5th May 2006
B.Allanach et.al., hep-ph/0507283
mtop
= 174.3±3.4 GeV/c2
mb(mb)MS = 4.2±0.2 GeV/c2
s(Z)MS =0.1187 ± 0.002
BR(b->sg) = 3.52±0.42x10-9
DMh2
= 0.1126±0.009,
-10
(g-2)Giulia
/2 =Manca,
19.0 University
± 8.4x10
of Liverpool
Charginos and Neutralinos
in GMSB
44
Why Charginos and Neutralinos ?
• They are light (~ 100-500 GeV/c2)
Squarks and gluinos too heavy for the Tevatron
• They decay giving striking signatures
In mSugra : 3 isolated leptons + /
ET
In GMSB : 2 photons +/
ET
In AMSB : long-lived particles
In R
/p models : >3 leptons
(and many more signatures in each model
depending on the parameters !)
5th May 2006
Giulia Manca, University of Liverpool
45
Motivation: Run I CDF Event
•
CDF Run I event:
•
Interpretations in GMSB:
•
•
 2 e, 2 g and Et=56 GeV
 SM expectaction: 10-6 Events
 Selectron
 Chargino/Neutralino
/
Visible in inclusive diphoton Et
spectrum
Searched by Tevatron Run II, LEP
and
HERA
Phys.Rev.Lett.81:1791-1796,1998
5th May 2006
Giulia Manca, University of Liverpool
46
Chargino Neutralino in gg+ET
In GMSB: 2 photons+ET
D0(CDF) Event selection:
-2 photons ET -> 20(13) GeV
-ET>40(45) GeV
SM Expected
OBSERVED
D0
3.7±0.6
2
CDF
0.3±0.1
0
CDF‡ and D0#
combined result:
m(c±)>209 GeV/c2
‡Phys.Rev.D.71,3 031104(2004)
#Phys. Rev. Letters 94,
041801(2005)
5th May 2006
Giulia Manca, University of Liverpool
47
Chargino Neutralino in gg+ET
In GMSB: 2 photons+ET
D0 Event selection (L=760
-2 photons ET -> 25 GeV
-ET>45GeV
5th May 2006
pb-1):
D0
SM Expected
OBSERVED
2.1±0.7
4
D0 new result :
m(c±)>220 GeV/c2
Giulia Manca, University of Liverpool
Charginos and Neutralinos
in AMSB
49
Why Charginos and Neutralinos ?
• They are light (~ 100-500 GeV/c2)
Squarks and gluinos too heavy for the Tevatron
• They decay giving striking signatures
In mSugra : 3 isolated leptons + E
/T
In GMSB : 2 photons +/
ET
In AMSB : long-lived particles
In R
/p models : >3 leptons
(and many more signatures in each model
depending on the parameters !)
5th May 2006
Giulia Manca, University of Liverpool
50
Charginos in AMSB
In the AMSB scenario (c01 LSP)
• c±1 is the NLSP (Next-to-Lightest-Supersymmetric Particle)
• lives long enough to decay outside the detector;
•c and the BR depend almost entirely upon the mass difference c±1-c01
c±1-> c01
5th May 2006
M(
Giulia Manca, University of Liverpool
51
Champs
CHArged Massive stable Particles:
-electrically charged
-massive->speed<<c
-lifetime long enough to decay
outside detector
Event Selection:
-2 muons Pt> 15 GeV, isolated
-Speed significantly slower than c
100 GeV Staus
100 GeV Higgsino-like
Chargino
100 GeV Gaugino-like
Chargino
No SM Background!!->from DATA
Expected
OBSERVED
0.66±0.06
0
Limits in AMSB:
champ = ~
c± 
~±
M(c
1)>174
GeV/c2
5th May 2006
Giulia Manca, University of Liverpool
Charginos and Neutralinos
in Rp violating
53
Why Charginos and Neutralinos ?
• They are light (~ 100-500 GeV/c2)
Squarks and gluinos too heavy for the Tevatron
• They decay giving striking signatures
In mSugra : 3 isolated leptons + /
ET
In GMSB : 2 photons +/
ET
In AMSB : long-lived particles
In R
/p models : >3 leptons
(and many more signatures in each model
depending on the parameters !)
5th May 2006
Giulia Manca, University of Liverpool
54
•
R Parity Violation
RPV tested in Production and Decay of SUSY particles
-d
d
´211
~
c01 ~+

~
´211
u
-u
Resonant sparticle
production
-> ’ijk coupling
Selection:
2jets+2isolated ’s
 ’211
5th May 2006
133
122


RPV decay of LSP(c01)
-> ijk coupling
Selection:
3 (=e,)+ET+channel
dependent cuts
 121 ->(eeee,eee,ee+
 122 ->(,e,ee) +
Giulia Manca, University of Liverpool
55
•
RPV Neutralino Decay
Model:
 R-parity conserving production => two
•
•
neutralinos
 R-parity violating decay into leptons
 One RPV couplings non-0: 122 , 121
Final state: 4 leptons +Et
 eee, ee, e, 
 3rd lepton Pt>3 GeV
 Largest Background: bb
Obs.
Exp.
eel (l=e,)
0
0.5±0.4
l (l=e,)
2
0.6+1.9-0.6
Interpret:
 M0=250 GeV, tan=5
121>0
122>0
~
m(c+1) >165 GeV
5th May 2006
~
m(c+1) >181 GeV
Giulia Manca, University of Liverpool
56
•
RPV Neutralino Decay
Model:
 R-parity conserving production => two
neutralinos
 R-parity violating decay into leptons
 One RPV couplings non-0: 122 , 121
•
Final state: 4 leptons +Et
•
Interpret:
~+ ) >199 GeV
m(c
1
 eee, ee, e, 
 3rd lepton Pt>5 GeV
 Largest Background: DY+conversion
 M0=250 GeV, tan=5
Obs.
Exp.
l (l=e,)
1
3.8 ±0.4
eel (l=e,)
5
4.3±0.4
5th May 2006
122>0
121>0
~
m(c+1) >172.6 GeV/c2
Giulia Manca, University of Liverpool
58
•
Chargino-Neutralino: Present
Lots of searches setting limits on c0(+) masses from
different sides
c0 c±
Rp
M(c±)>199
•
•
AMSB
M(c±)>174 GMSB
M(c±)>220
mSugra
M(c±)>127
Getting close to the most favoured masses!
Still ~1 fb-1 to analyse ! => Observation ? Or better limits…
 Hints from the Tevatron will help LHC to prioritise searches
5th May 2006
Giulia Manca, University of Liverpool
What about the future ?
60
•
•
•
Susy at the LHC !
Will generally be found
fast!
But SUSY comes in very
many flavours
Hints from the Tevatron
would help on search
priorities, e.g.
 tan large:
 3rd generation
important
(’s, b’s)
 R-parity is violated
 No ET
 GMSB models:
 Photons important
 Split-SUSY:
 Stable charged
hadrons
 Can setup triggers
Inclusive search
STATISTICAL
reach only
up to 2.8 TeV
up to 2.3 TeV
up to 2 TeV
accordingly
5th May 2006
Giulia Manca, University of Liverpool
61
•
•
•
Susy at the LHC !
Will generally be found
fast!
But SUSY comes in very
many flavours
Hints from the Tevatron
would help on search
priorities, e.g.
 tan large:
 3rd generation
important
(’s, b’s)
 R-parity is violated
 No ET
 GMSB models:
 Photons important
 Split-SUSY:
 Stable charged
hadrons
 Can setup triggers
Inclusive search
STATISTICAL
reach only
up to 2.8 TeV
up to 2.3 TeV
up to 2 TeV
accordingly
5th May 2006
Giulia Manca, University of Liverpool
62
•
Production Cross-sections at the
LHC
In mSugra:
 squark-gluino dominate
•
(pb)
SUSY (pb) vs sparticle
mass(GeV/c2) for √s=14 TeV
(jets+met channel)
T. Plehn, PROSPINO
Direct production crosssections small
300k
events
in 3fb-1
 But could be the only way
•
to observe SUSY if
quark-gluinos are heavy
! (“focus point”)
3,000
events
in 3fb-1
0 
c  c±
In other regions trileptons
signal enhanced from
squark-gluino cascade
mass(GeV/c2)
But also :
6x106 Zs, 2.4x106 t-antitop and
150,000 WZ !
5th May 2006
Giulia Manca, University of Liverpool
63
•
•
Mass measurement at the LHC
Mass constraints
Invariant masses in
pairs
 Missing energy
 Kinematic edges
Observable:
Depends on:
Limits depend on
angles between
sparticle decays
5th May 2006
Giulia Manca, University of Liverpool
64
Building on leptons…
• Other possibilities with lepton
signatures in mSugra:
Jets+MET+leptons -> mass of the
sparticles in the cascade
Like-sign dileptons -> still sensitive to
chargino-neutralino but also on gluino pair
production ! (no jet veto)
R-parity violating scenarios
5th May 2006
Giulia Manca, University of Liverpool
65
Conclusions
• Chargino-neutralino are the golden
•
•
discovery mode at the Tevatron in virtually
all the models
Hints from the Tevatron can give
directions to the LHC
At the LHC, chargino-neutralino
production crucial in study the properties
of the new sparticles as their masses (but
only mSugra considered)
• Exciting times to come !!
5th May 2006
Giulia Manca, University of Liverpool