Transcript Prospects for SUSY at ATLAS and CMS

Supersymmetry
at ATLAS
Dan Tovey
University of Sheffield
Dan Tovey
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Sapporo, June 2007
ATLAS
Length: ~45 m
Radius: ~12 m
Weight: ~7000 tons
Dan Tovey
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Dan Tovey
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SUSY @ ATLAS
• Many motivations for
low-scale SUSY:
– Gauge hierarchy
problem
– Higgs mass
– Coupling constant
unification
– Dark Matter candidate
~0
c
1
MET
• Focus here on R-Parity
Conserving models
– Dark Matter Candidate
 ETmiss signature
• NB ETmiss signature
valid for any DM
candidate (not just
SUSY)
~
c 01
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ATLAS SUSY Strategy
SUSY studies at ATLAS will proceed in three stages:
1) SUSY Discovery phase
2) Inclusive Studies
– comparison of significance in inclusive channels,
– measurement of SUSY Mass Scale.
3) Exclusive studies
–
–
–
–
–
Dan Tovey
model-dependent interpretation (e.g. mSUGRA DM),
less model-dependent DM,
universalities / flavour physics,
spin measurement (is it SUSY?),
….
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Stage 1:
SUSY Discovery
Dan Tovey
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SUSY Signatures
• Q: What do we expect SUSY events @ LHC to look like?
• A: Look at typical decay chain:
p
p
~
g
q
~
q
~
c0 2
q
~
c0 1
~
l
l
l
• Strongly interacting sparticles (squarks, gluinos) dominate
production.
• Heavier than sleptons, gauginos etc. g cascade decays to LSP.
• Long decay chains and large mass differences between SUSY states
– Many high pT objects observed (leptons, jets, b-jets).
• If R-Parity conserved LSP (lightest neutralino in mSUGRA) stable
and sparticles pair produced.
– Large ETmiss signature (c.f. Wgln).
• Closest equivalent SM signature tgWb.
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Inclusive Searches
•
•
•
•
Use 'golden' Jets + n leptons + ETmiss discovery channel.
Map statistical discovery reach in mSUGRA m0-m1/2 parameter space.
Sensitivity only weakly dependent on A0, tan(b) and sign(m).
Syst.+ stat. reach harder to assess: focus of current & future work.
5s
5s
ATLAS
Dan Tovey
ATLAS
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Monte Carlo Studies
• Monte Carlo background estimates
subject to significant systematics
• Original studies used Parton Shower
• Recent studies use ALPGEN MPFS
generator + MLM matching to PS
• Re-assessment of significances
Jets + ETmiss + 0 leptons
Meff=S|pTi| + ETmiss
ATLAS
10 fb-1
Meff=S|pTi| + ETmiss
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Background Estimation
• Inclusive signature: jets + n leptons +
ETmiss
• Main backgrounds:
–
–
–
–
Z + n jets
W + n jets
QCD
ttbar
• Greatest discrimination power from
(R-Parity conserving models)
• Generic approach to background
estimation:
ETmiss
– Select background calibration samples
(control region);
– Extrapolate into high ETmiss signal region.
One lepton mode BG @ 1fb-1
•Blue: tt(lnln)
Preliminary
•Green: tt(lnqq)
•Red: w
•Black: sum BG
•Pink: SU3
ATLAS
Meff=S|pTi| + ETmiss Effective mass (GeV)
Jets + ETmiss + 1 lepton
10 fb-1
Meff=S|pTi| + ETmiss
• Used by CDF / D0
• Extrapolation is non-trivial.
– Must find variables uncorrelated with ETmiss
• Several approaches being developed.
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W/Z+Jets Background
• Z g nn + n jets, W g ln + n jets, W g
tn + (n-1) jets (t fakes jet)
• Estimate from Z g l+l- + n jets (e or m)
• Tag leptonic Z and use to validate MC
/ estimate ETmiss from pT(Z) & pT(l)
• Alternatively tag W g ln + n jets and
replace lepton with n (0l):
(Zll)
ATLAS
Preliminary
– higher stats
– biased by presence of SUSY
ATLAS
(Wln)
Preliminary
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Top Background
• Jets + ETmiss + 1 lepton: cut hard on
mT(ETmiss, l)
• Rejects bulk of ttbar (semi-leptonic
decays), W g ln + n jets
• Remaining background mostly fully
leptonic top decays (ttbblnln,
ttbbtnln, ttbbtntn) with one top
missed (e.g. hadronic tau)
Type of Event
ATLAS
Preliminary
Edge at W Mass
• tt(lnln)
• tt(lnqq)
• w+jet
• sum of all BG
• Pink: SU3
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Number of Events
Electron-Electron
67
Muon-Muon
80
Tau-Tau
14
Electron-Muon
152
Electron-Tau
100
Muon-Tau
109
Electron-Hadron
77
Muon-Hadron
174
Tau-Hadron
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Top Background
Control region
Signal region
Signal region
ATLAS
ATLAS
Preliminary
Preliminary
Missing ET (GeV)
Transverse Mass (GeV)
•
ATLAS
One possibility  use mT(W)
– Divide mT into signal region +
control region (mT<100GeV)
– Use shape of control distribution for
ETmiss or Effective Mass
– normalization factor determined in
the low ETmiss region (100 200GeV)
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Preliminary
Control region
•tt(lnln)
•tt(lnqq)
•w
•sum BG
•SU3
Missing ET (GeV)
normalization region
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mT Method
@1fb-1
ATLAS
@1fb-1
real BG
estimated BG
>300GeV
9.5±1.1
8.6±0.6
real BG
estimated BG
>800GeV
24.8±1.6
22.0±0.9
ATLAS
Preliminary
Preliminary
Meff=S|pTi| + ETmiss Effective Mass (GeV)
Missing ET (GeV)
• With cut mT > 100 GeV, BG well
reproduced in absence of SUSY
signal (statistical error ~ 10%)
• With SUSY signal estimated BG
increased by factor ~2.5.
• Rejection of SUSY contamination
next issue
With SU3 signal
>800GeV
24.8±1.6
60.8±2.5
ATLAS
Preliminary
Effective Mass (GeV)
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QCD Background
• Two main sources:
– fake ETmiss (gaps in acceptance, dead/hot
cells, non-gaussian tails etc.)
– real ETmiss (neutrinos from b/c quark
decays)
• Much harder with MC : simulations
require detailed understanding of
detector performance
• Strategy:
Pythia dijets
1) Initially choose channels which minimise
contribution until well understood (e.g.
jets + ETmiss + 1l)
2) Reject events where fake ETmiss likely:
beam-gas and machine background, bad primary
vertex, hot cells, CR muons, ETmiss phi correlations (jet
fluctuations), jets pointing at regions of poor
response …
3) Cut hard to minimise contribution to
background (at expense of stats).
4) Estimate background using data
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SUSY SU3
Sapporo, June 2007
QCD Background
• Work in Progress: several ideas under study
• Step 1: Measure jet smearing function from data
jets
– Select events: ETmiss > 100 GeV, Df(ETmiss, jet) < 0.1
MET
– Estimate pT of jet closest to EtMiss as
pTtrue-est = pTjet + ETMiss
• Step 2: Smear low ETmiss multijet events with
measured smearing function
fluctuating
jet
22pb-1
ATLAS
ATLAS
Preliminary
Preliminary
ETmiss
Dan Tovey
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Njets >= 4,
pT(j1,j2) >100GeV,
pT(j3,j4) > 50GeV
All
QCD
Znn
SU3
Estimate (QCD)
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Stage 2:
Inclusive Studies
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Inclusive Studies
• First indication of mSUGRA
parameters from inclusive channels
– Compare significance in jets + ETmiss +
n leptons channels
ATLAS
• Detailed measurements from
exclusive channels when accessible.
• Consider here two specific example
points studied previously:
Point
LHC Point 5
SPS1a
m0 m1/2 A0
100 300 300
100 250 -100
Sparticle Mass (LHC Point 5)
~
qL
~690 GeV
~
c02
233 GeV
~
lR
157 GeV
~
c01
122 GeV
Dan Tovey
tan(b) sign(m)
2
+1
10
+1
Mass (SPS1a)
~530 GeV
177 GeV
143 GeV
96 GeV
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LHC Point 5 (A0 =300
GeV, tan(b)=2, m>0)
Point SPS1a (A0 =-100
GeV, tan(b)=10, m>0)
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Inclusive Studies
• First SUSY parameter to be measured
may be mass scale:
– Defined as weighted mean of masses of
initial sparticles.
• Calculate distribution of 'effective mass'
variable defined as scalar sum of
masses of all jets (or four hardest) and
ETmiss:
Meff=S|pTi| + ETmiss.
• Distribution peaked at ~ twice SUSY
mass scale for signal events.
• Pseudo 'model-independent'
measurement.
• Typical measurement error (syst+stat)
~10% for mSUGRA models for 10 fb-1
(PS).
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Jets + ETmiss + 0 leptons
ATLAS
10 fb-1
Jets + ETmiss + 1 lepton
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Stage 3:
Exclusive studies
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Exclusive Studies
• With more data will attempt to measure weak scale SUSY parameters
(masses etc.) using exclusive channels.
• Different philosophy to TeV Run II (better S/B, longer decay chains) g
aim to use model-independent measures.
p
p
~
q
~g
q
~
c0 2
q
~
lR
l
~
c0 1
l
• Two neutral LSPs escape from each event
– Impossible to measure mass of each sparticle using one channel alone
• Use kinematic end-points to measure combinations of masses.
• Old technique used many times before (n mass from b decay
spectrum, W (transverse) mass in Wgln).
• Difference here is we don't know mass of neutral final state particles.
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Dilepton Edge Measurements
• When kinematically
accessible ~
c02 can undergo
sequential two-body decay
to ~
c01 via a right-slepton
(e.g. LHC Point 5).
• Results in sharp OS SF
dilepton invariant mass
edge sensitive to
combination of masses of
sparticles.
• Can perform SM & SUSY
background subtraction
using OF distribution
c~02
l
e+e-
c~01
l
e+e- + m+m- e+m- - m+e-
m+m-
+
Point 5
ATLAS
~
l
30 fb-1
atlfast
Physics
TDR
•m0 = 100 GeV
•m1/2 = 300 GeV
•A0 = -300 GeV
•tan(b) = 6
•sgn(m) = +1
ATLAS
5 fb-1
SU3
e+e- + m+m- - e+m- - m+e-
• Position of edge measured
with precision ~ 0.5%
(30 fb-1).
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Measurements With Squarks
•
•
•
•
Dilepton edge starting point for reconstruction of decay chain.
Make invariant mass combinations of leptons and jets.
Gives multiple constraints on combinations of four masses.
Sensitivity to individual sparticle masses.
~
qL
~
q c0 2
ATLAS
Dan Tovey
l
~
l
l
~
qL
~
c0 1
~
q c0 2
llq threshold
lq edge
1% error
(100 fb-1)
1% error
(100 fb-1)
TDR,
Point 5
ATLAS
h
b
llq edge
TDR,
Point 5
2% error
(100 fb-1)
TDR,
Point 5
ATLAS
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~
c0 1
b
bbq edge
1% error
(100 fb-1) TDR,
Point 5
ATLAS
Sapporo, June 2007
‘Model-Independent’ Masses
• Combine measurements from edges
from different jet/lepton
combinations to obtain ‘modelindependent’ mass measurements.
~
c0
ATLAS
Mass (GeV)
~c0
2
ATLAS
LHCC
Point 5
~
lR
1
Mass (GeV)
ATLAS
Mass (GeV)
~
q
L
ATLAS
Mass (GeV)
Sparticle Expected precision (100 fb-1)
~
qL
 3%
~
c02
 6%
~
lR
 9%
~
c01
 12%
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Measuring Model Parameters
• Alternative use for SUSY observables (invariant mass end-points,
thresholds etc.).
• Here assume mSUGRA/CMSSM model and perform global fit of model
parameters to observables
– So far mostly private codes but e.g. SFITTER, FITTINO now on the market;
– c.f. global EW fits at LEP, ZFITTER, TOPAZ0 etc.
Point
LHC Point 5
SPS1a
Parameter
m0
m1/2
tan(b)
A0
Dan Tovey
m0 m1/2 A0
100 300 300
100 250 -100
tan(b) sign(m)
2
+1
10
+1
Expected precision (300 fb-1)
 2%
 0.6%
 9%
 16%
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Dark Matter Parameters
• Can use parameter measurements
for many purposes, e.g. estimate
LSP Dark Matter properties (e.g.
for 300 fb-1, SPS1a)
– Wch2 = 0.1921  0.0053
– log10(scp/pb) = -8.17  0.04
Micromegas 1.1
(Belanger et al.)
+ ISASUGRA 7.69
Wc
h2
300 fb-1
ATLAS
Dan Tovey
Baer et al. hep-ph/0305191
LHC Point 5: >5s error (300 fb-1)
SPS1a: >5s
error (300 fb-1)
scp=10-11 pb
DarkSUSY 3.14.02
(Gondolo et al.)
+ ISASUGRA 7.69
scp=10-10 pb
scp
scp=10-9 pb
300 fb-1
LEP 2
No REWSB
ATLAS
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Target Models
• SUSY (e.g. mSUGRA) parameter space strongly constrained by
cosmology (e.g. WMAP satellite) data. mSUGRA A0=0,
tan(b) = 10, m>0
'Focus point'
region:
~
significant h
component to
LSP enhances
annihilation to
gauge bosons
'Bulk' region: tchannel slepton
exchange - LSP
mostly Bino.
'Bread and
Butter' region for
LHC Expts.
Dan Tovey
Ellis et al. hep-ph/0303043
Disfavoured by BR (b  sg) =
(3.2  0.5)  10-4 (CLEO, BELLE)
c~01
c~01
~0
c
1
l
~
lR
t~1
t
t~1
g/Z/h
Slepton Coannihilation
region: LSP ~
pure Bino. Small
slepton-LSP
mass difference
makes
measurements
difficult.
l
Also 'rapid
annihilation funnel'
at Higgs pole at
0.094  W c h2  0.129
(WMAP)
high tan(b), stop
co-annihilation
region at large A0
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Coannihilation Signatures
• Small slepton-neutralino mass
difference gives soft leptons
100 fb-1
– Low electron/muon/tau energy
thresholds crucial.
ATLAS
• Study point chosen within region:
– m0=70 GeV; m1/2=350 GeV; A0=0;
tanß=10 ; μ>0;
Preliminary
~
~
• Decays of c~02 to both lL and lR
kinematically allowed.
– Double dilepton invariant mass
edge structure;
– Edges expected at 57 / 101 GeV
100 fb-1
• Stau channels enhanced (tanb)
– Soft tau signatures;
– Edge expected at 79 GeV;
– Less clear due to poor tau visible
energy resolution.
Dan Tovey
• ETmiss>300 GeV
• 2 OSSF leptons
PT>10 GeV
• >1 jet with PT>150
GeV
• OSSF-OSOF
subtraction applied
Preliminary
28
ATLAS
• ETmiss>300 GeV
• 1 tau PT>40
GeV;1 tau PT<25
GeV
• >1 jet with
PT>100 GeV
• SS tau
subtraction
Sapporo, June 2007
Focus Point Signatures
• Large m0  sfermions are heavy
• Most useful signatures from heavy neutralino decay
• Study point chosen within focus point region :
– m0=3550 GeV; m1/2=300 GeV; A0=0; tanß=10 ; μ>0
~0 → c
~0 ll
• Direct three-body decays c
n
1
~0 )-m(c
~ 0 ) : flavour subtraction applied
• Edges give m(c
n
1
~0 → ~
~
c01 ll
c 02 → ~
c01 ll c
3
Z0 → ll
M = mA+mB m = mA-mB
ATLAS
300 fb-1
Preliminary
Dan Tovey
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Parameter
Without cuts
Exp. value
M1
68±92
103.35
M2-M1
57.7±1.0
57.03
M3-M1
77.6±1.0
76.41
Sapporo, June 2007
Dark Matter in the MSSM
• Can relax mSUGRA constraints to obtain
more ‘model-independent’ relic density
estimate.
• Much harder – needs more measurements
• Not sufficient to measure relevant (co-)
annihilation channels – must exclude all
irrelevant ones also …
• Stau, higgs, stop masses/mixings important
as well as gaugino/higgsino parameters
Nojiri et al., JHEP 0603 (2006) 063
Wc
σ(mtt)=
5 GeV
Wch2
300 fb-1
σ(Wch2) vs
σ(mtt)
h2
σ(mtt)=
0.5 GeV
300 fb-1
SPA point
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Heavy Gaugino Measurements
• Potentially possible to identify dilepton
edges from decays of heavy gauginos.
• Requires high stats.
• Crucial input to reconstruction of MSSM
neutralino mass matrix (independent of
SUSY breaking scenario).
ATLAS
SPS1a
ATLAS
100 fb-1
Dan Tovey
ATLAS
100 fb-1
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ATLAS
100 fb-1
SPS1a
Sapporo, June 2007
SUSY Spin Measurement
• Q: How do we know that a SUSY signal is really due to SUSY?
– Other models (e.g. UED) can mimic SUSY mass spectrum
• A: Measure spin of new particles.
• One proposal – use ‘standard’ two-body slepton decay chain
– charge asymmetry of lq pairs measures spin of ~c02
– relies on valence quark contribution to pdf of proton (C asymmetry)
– shape of dilepton invariant mass spectrum measures slepton spin
Spin-0
Measure
Angle
A
Spin-½

l l
=  
l l
Point 5
Point 5
ATLAS
150 fb -1
mlq
spin-0=flat
Polarise
Spin-½,
Spin-0
mostly wino
Dan Tovey
150 fb -1
ATLAS
Straight
line distn
(phase-space)
Spin-½,
mostly bino
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Supersummary
• The LHC will be THE PLACE to search for, and hopefully study,
SUSY from next year onwards at colliders (at least until ILC).
• SUSY searches (preparations) will commence on Day 1 of LHC
operation.
• Many studies of exclusive channels already performed.
• Lots of input from both theorists (new ideas) and
experimentalists (new techniques).
• Big challenge for discovery will be understanding systematics.
• Big effort now to understand how to exploit first data in timely
fashion
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BACK-UP SLIDES
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Supersymmetry
• Supersymmetry (SUSY) fundamental
continuous symmetry connecting
fermions and bosons
Qa|F> = |B>,
Qa|B> = |F>
• {Qa,Qb}=-2gmabpm: generators obey anticommutation relations with 4-mom
– Connection to space-time symmetry
• SUSY stabilises Higgs mass against loop
corrections (gauge hierarchy/fine-tuning
problem)
LEPEWWG
Winter 2006
mH<207 GeV
(95%CL)
– Leads to Higgs mass  135 GeV
– Good agreement with LEP constraints from
EW global fits
• SUSY modifies running of SM gauge
couplings ‘just enough’ to give Grand
Unification at single scale.
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SUSY Spectrum
• SUSY gives rise to partners of SM states with opposite spin-statistics
but otherwise same Quantum Numbers.
• Expect SUSY
partners to
have same
masses as SM
states
– Not
observed
(despite best
efforts!)
– SUSY must
be a broken
symmetry at
low energy
• Higgs sector
also expanded
Dan Tovey
h
A
H0
H±
u
d
e
ne
c
s
m
t
b
t
g
Z
W±
~
~0 0 ~~0 + ~0~ ~
~
0
0
c
H 1u cH2 d cH3 u c H4 d
nm
~
u
~
c
~
d
~
s
~
e
~
m
~
ne
~
n
nt
~
t
~
b
~
t
~
nt
g
~
~~
±~ ±
~
c
cW
g ± 1Z
2
~
g
G
~
G
36
m
Sapporo, June 2007
SUSY & Dark Matter
• R-Parity Rp = (-1)3B+2S+L
• Conservation of Rp
(motivated e.g. by string
models) attractive
mSUGRA A0=0,
tan(b) = 10, m>0
Ellis et al. hep-ph/0303043
Disfavoured by BR Universe
(b  sg) =Over-Closed
-4
(3.2  0.5)  10 (CLEO, BELLE)
– e.g. protects proton from
rapid decay via SUSY states
• Causes Lightest SUSY
Particle (LSP) to be
absolutely stable
• LSP neutral/weakly
interacting to escape
astroparticle bounds on
anomalous heavy elements.
• Naturally provides solution to
dark matter problem
• R-Parity violating models still
possible  not covered here.
Dan Tovey
c~01
c~01
~0
c
1
l
~
lR
t~1
t
t~1
g/Z/h
l
0.094  W c h2  0.129
(WMAP-1year)
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SUSY @ ATLAS
• LHC will be a 14 TeV proton-proton
collider located inside the LEP
tunnel at CERN.
• Luminosity goals:
– 10 fb-1 / year (first ~3 years)
– 100 fb-1/year (subsequently).
• First data this year!
• Higgs & SUSY main goals.
• Much preparatory work carried out
historically by ATLAS
– Summarised in Detector and
Physics Performance TDR (1998/9).
• Work continuing to ensure ready to
test new ideas with first data.
• Concentrate here on more recent
work.
Dan Tovey
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Model Framework
• Minimal Supersymmetric Extension of the Standard Model (MSSM)
contains > 105 free parameters, NMSSM etc. has more g difficult to
map complete parameter space!
• Assume specific well-motivated model framework in which generic
signatures can be studied.
• Often assume SUSY broken by gravitational interactions g
mSUGRA/CMSSM framework : unified masses and couplings at the
GUT scale g 5 free parameters
LHCC
(m0, m1/2, A0, tan(b), sgn(m)).
mSUGRA
• R-Parity assumed to be conserved.
Points
• Exclusive studies use benchmark
3
points in mSUGRA parameter space:
•
•
•
•
LHCC Points 1-6;
Post-LEP benchmarks (Battaglia et al.);
Snowmass Points and Slopes (SPS);
etc…
Dan Tovey
39
5
1
2
4
Sapporo, June 2007
RH Squark Mass
• Right handed squarks difficult as rarely decay via ‘standard’ ~
c02 chain
~ gc
~0 q) > 99%.
– Typically BR (q
R
1
• Instead search for events with 2 hard jets and lots of ETmiss.
• Reconstruct mass using ‘stransverse mass’ (Allanach et al.):
mT22 =
min
c(1)
c(2)
miss
[max{mT2(pTj(1),qTc(1);mc),mT2(pTj(2),qTc(2);mc)}]
q
+q
=E
~
0
• Needs c 1 mass measurement as input.
• Also works for sleptons.
T
T
T
~
c0 1
q
ATLAS
ATLAS
30 fb-1
30 fb-1
Right
squark
SPS1a
~
qR
ATLAS
100 fb-1
SPS1a
SPS1a
Right
squark
Left slepton
Precision ~ 3%
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40
Sapporo, June 2007
Inclusive Studies
• Following any discovery of SUSY next
task will be to test broad features of
model.
• Question 1: Is R-Parity Conserved?
– If YES possible DM candidate
– LHC experiments sensitive only to LSP
lifetimes < 1 ms (<< tU ~ 13.7 Gyr)
~
Non-pointing
~
~
photons from c01gGg
R-Parity
Conserved
R-Parity
Violated
ATLAS
• Question 2: Is the LSP the lightest
neutralino?
– Natural in many MSSM models
– If YES then test for consistency with
astrophysics
– If NO then what is it?
– e.g. Light Gravitino DM from GMSB
models (not considered here)
GMSB Point 1b
(Physics TDR)
ATLAS
Dan Tovey
LHC Point 5
(Physics TDR)
41
Sapporo, June 2007
Decay Resimulation
•
•
•
Second approach: Decay Resimulation
Goal is to model complex background events using samples of
tagged SM events.
Initially we will know:
– a lot about decays of SM particles (e.g. W, top)
– a reasonable amount about the (gaussian) performance of the detector.
– rather little about PDFs, the hard process and UE.
•
Philosophy
–
–
–
–
–
–
–
•
•
Tag ‘seed’ events containing W/top
Reconstruct 4-momentum of W/top (x2 if e.g. ttbar)
Decay/hadronise with e.g. Pythia
Simulate decay products with atlfast(here) or fullsim
Remove original decay products from seed event
Merge new decay products with seed event (inc. ETmiss)
Perform standard SUSY analysis on merged event
Technique applicable to wide range of channels (not just SUSY)
Involves measurement of (top) pT: useful for exotic-top searches?
Dan Tovey
42
Sapporo, June 2007
Decay Resimulation
• Select seed events:
–
–
–
–
m(lb)
2 leptons with pT>25GeV
2 jets with pT>50GeV
ETmiss < <pT(l1),pT(l2)> (SUSY)
Both m(lb) < 155GeV
Zmm
• Solve 6 constraints for p(n)
• Resimulate + merge with seed
• Apply 1l SUSY cuts
cut
ATLAS
Preliminary
GeV
ETmiss
Sample 5201,
pT(top) > 200 GeV
reco 11.0.4205,
450 pb-1
ATLAS
Pull
(top pT)
Preliminary
>=2 jets,
Normalisation to
data under study
ATLAS
Preliminary
Dan Tovey
Estimate
5201
43
Sapporo, June 2007