Exotics with Dileptons and
More
Maxwell Chertok UC Davis
From LHC to the Universe National Taiwan University
Taipei, Dec. 2008
M. Chertok NTU-UC Davis Workshop
Outline
HERA: hints in 1990’s CDF in Run I
‣ LS search for SUSY (RPV/RPC)
CDF in Run II
‣ LS Search
‣ Vista/Sleuth
‣ New LS Search
LHC Era Searching
Thoughts on collaborating
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Excitement from HERA
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circa 1997 at HERA
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Excess at high Q 2
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Notice mass clustering
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200 GeV Leptoquark?
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Maximize Discovery Potential
Search for Higgs and SUSY in leptonic channels
‣ Hadron collider: most backgrounds (mb) are jets
‣ CDF/CMS: excellent tracking, momentum resolution, dedicated electron and muon detection
‣ Powerful signatures:
dileptons + jets + MET LS dileptons
trileptons
with and without hadronic tau
decays
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When hadrons collide
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Supergravity Masses
mSUGRA Mass Spectrum
GUT scale GUT scale EW scale
EW scale
4.5 parameters
m m
0
1/2
q
t g
l q
t
χ
1 2
∼
∼
∼
∼
∼
∼ ∼
stau light if τ~
appreciable mixing
l
LS Search at Run I
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Theory favorite
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Tevatron: pair
production
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Production & Decay
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The search
Start with 460K low-Pt dileptons Et(e 1,2 ) > 15 GeV
Calorimeter isolation 2 or more jets
Et(j 1,2 ) > 15 GeV Little MET
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0 Observed
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Reject charm squark LQs
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LS RPC SUSY @ Run I
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Leptonic branching
ratios
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Power of LS
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LS Search @ Run II
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LS electrons and muons
Inclusive search:
‣ Predict 33.7±4.7 from SM, Observe 44
22
Invariant mass (GeV) 40 60 80 100 120 140 160 180
events/bin
0 2 4 6 8 10 12 14
Invariant mass (GeV) 40 60 80 100 120 140 160 180
events/bin
0 2 4 6 8 10 12
14 Data
QCD WW/ZZ W !
WZ
Drell-Yan
L dt = 1.0 fb
-1"
CDF Run II Preliminary
Leading lepton Pt (GeV/c)
20 40 60 80 100 120
events/bin
0 2 4 6 8 10 12 14 16
Leading lepton Pt (GeV/c)
20 40 60 80 100 120
events/bin
0 2 4 6 8 10 12 14 16
Data QCD WW/ZZ W !
WZ
Drell-Yan
L dt = 1.0 fb
-1"
CDF Run II Preliminary
Met
0 20 40 60 80 100
events/bin
0 2 4 6 8 10 12
Met
0 20 40 60 80 100
events/bin
0 2 4 6 8 10 12
Data QCD WW/ZZ W !
WZ
Drell-Yan
L dt = 1.0 fb
-1"
CDF Run II Preliminary
Second lepton Pt (GeV/c)
10 20 30 40 50 60
events/bin
0 2 4 6 8 10 12 14 16 18 20 22
Second lepton Pt (GeV/c)
10 20 30 40 50 60
events/bin
0 2 4 6 8 10 12 14 16 18 20
22 Data
QCD WW/ZZ W !
WZ
Drell-Yan
L dt = 1.0 fb
-1"
CDF Run II Preliminary
FIG. 1: Invariant mass distribution and the leading lepton transverse momentum in data and simulation
[1] T. Han et al, arXiv:hep-ph/0604064.
[2] D. Acosta et al., Phys. Rev. Lett. 93, 061802 (2004).
[3] D. Acosta et al., Phys. Rev. D 71, 032001 (2005).
[4] C.S. Hill, Nucl. Instrum. Methods, A530, 1 (2004). A. Sill, et al., Nucl. Instrum. Meth- ods, A447, 1 (2000). A. Affolder, et al., Nucl. Instrum. Methods, A453, 84 (2000).
[5] T. Affolder et al., Nucl. Instrum. Methods, A526, 249 (2004).
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Invariant mass (GeV) 40 60 80 100 120 140 160 180
events/bin
0 2 4 6 8 10 12 14
Invariant mass (GeV) 40 60 80 100 120 140 160 180
events/bin
0 2 4 6 8 10 12
14
DataQCD WW/ZZ W!
WZ
Drell-Yan
L dt = 1.0 fb
-1"
CDF Run II Preliminary
Leading lepton Pt (GeV/c)
20 40 60 80 100 120
events/bin
0 2 4 6 8 10 12 14 16
Leading lepton Pt (GeV/c)
20 40 60 80 100 120
events/bin
0 2 4 6 8 10 12 14 16
Data QCD WW/ZZ W!
WZ
Drell-Yan
L dt = 1.0 fb
-1"
CDF Run II Preliminary
Met
0 20 40 60 80 100
events/bin
0 2 4 6 8 10 12
Met
0 20 40 60 80 100
events/bin
0 2 4 6 8 10 12
Data QCD WW/ZZ W!
WZ
Drell-Yan
L dt = 1.0 fb
-1"
CDF Run II Preliminary
Second lepton Pt (GeV/c)
10 20 30 40 50 60
events/bin
0 2 4 6 8 10 12 14 16 18 20 22
Second lepton Pt (GeV/c)
10 20 30 40 50 60
events/bin
0 2 4 6 8 10 12 14 16 18 20
22
DataQCD WW/ZZ W!
WZ
Drell-Yan
L dt = 1.0 fb
-1"
CDF Run II Preliminary
FIG. 1: Invariant mass distribution and the leading lepton transverse momentum in data and simulation
[1] T. Han et al, arXiv:hep-ph/0604064.
[2] D. Acosta et al., Phys. Rev. Lett. 93, 061802 (2004).
[3] D. Acosta et al., Phys. Rev. D 71, 032001 (2005).
[4] C.S. Hill, Nucl. Instrum. Methods, A530, 1 (2004). A. Sill, et al., Nucl. Instrum. Meth- ods, A447, 1 (2000). A. Affolder, et al., Nucl. Instrum. Methods, A453, 84 (2000).
[5] T. Affolder et al., Nucl. Instrum. Methods, A526, 249 (2004).
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LS electrons and muons
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Tighter cuts: MET>15, Z mass veto
Predict 7.9±1.1 from SM, Observe 13
Probability of fluctuation 7.3%
Sleuth
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Sleuth analysis
Sleuth looked for discrepancies with SM in Run II data using the high-Pt tails of kinematic
distributions
Top 5 discrepancies involve LS !!
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Sleuth LS
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New UC Davis LS Search
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Enhanced LS search
Use 3/fb data
Improve acceptance:
‣ First electron or muon: Pt > 20 GeV
‣ Second: Pt > 8 GeV with looser ID requirements
‣ Use OS events as control region
Event level
‣ M(ll) > 25 GeV; MET > 15 GeV
‣ Remove Z window for OS events
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OS Control regions
All low mass
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Signal region & plans
Remaining to do
‣ Add Z-gamma
‣ Apply j → lepton fake rates
‣ Confirm CR look good
‣ Open the box!
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We’ll have to get back
to ya on that one...
Trileptons @ high tan
beta
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Lepton+Track Triggers
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‣ Original motivation:
N2C1 with taus
Keep Pt cuts as low as possible
‣ 1 hadronic + 1 leptonic decay
Optimizes tradeoff between Br and efficiency
‣ Excellent use in Run II
Z to tau pairs RPV Stop
3rd Gen Leptoquarks Doubly charged Higgs MSSM Higgs
High mass Higgs
SUSY Trileptons with Taus
Hadronic Taus add sensitivity to previously unexplored
high SUSY space.
Plan to use L2 Upgraded Lepton + Track triggers to search for events with up to 2
hadronic taus.
Signature: 3 Leptons + MET
FIGURE 64. Cross section of p¯ p → ˜ χ
±1χ ˜
02→ 3 leptons + X without cuts at √
s = 2 TeV versus tan β, with µ > 0, m
1/2= 200 GeV, m
0= 100 GeV for (a) τ τ τ (solid), (b) τ τ $ (dot-dash), (c) τ $$ (dash) and (d) $$$ (dot), where $ = e or µ.
In Figure 65, we present branching fractions of ˜ χ 0 2 versus tan β with µ > 0 as well as µ < 0 for m 1/2 = 200 GeV and several values of m 0 . 18 For tan β < ∼ 5, the branching fractions are sensitive to the sign of µ.
For µ > 0 and tan β ∼ 3, we have found that:
• For m 0 <
∼ 100 GeV, ˜ χ 0 2 decays dominantly to ˜ # R # and ˜ τ 1 τ , and ˜ χ ± 1 decays into ˜ τ 1 ν,
• For 120 GeV < ∼ m 0 <
∼ 170 GeV, the ˜ χ ± 1 χ ˜ 0 2 → 3# + E/ T branching fraction is still significant due to light virtual sleptons.
• For m 0 >
∼ 180 GeV, ˜ χ ± 1 and ˜ χ 0 2 dominantly decay into q ¯ q ! χ ˜ 0 1 . For µ < 0 and tan β ∼ 3, we have found that:
• For m 0 <
∼ 140 GeV, ˜ χ 0 2 dominantly decays to ˜ ν L ν, ˜ # R #, and ˜ τ 1 τ , and ˜ χ ± 1 decays into ˜ ν L # and ˜ τ 1 ν.
• For 140 GeV < ∼ m 0 <
∼ 160 GeV, the ˜ χ ± 1 χ ˜ 0 2 → 3# + E/ T branching fraction is still significant due to light virtual sleptons.
• For m 0 >
∼ 170 GeV, ˜ χ ± 1 and ˜ χ 0 2 dominantly decay into q ¯ q ! χ ˜ 0 1 .
For µ > 0 and m 0 ∼ 200 GeV, ˜ χ 0 2 dominantly decays (i) into τ ¯ τ ˜ χ 0 1 for 25 < ∼ tan β <
∼ 40, (ii) into τ ˜τ 1 for tan β > ∼ 40. For m 0 <
∼ 300 GeV and tan β >
∼ 35, both ˜τ 1 and ˜b 1 can be lighter than other sfermions, and ˜ χ ± 1 and ˜ χ 0 2 can decay dominantly into final states with τ or b via virtual or real ˜ τ 1 and ˜b 1 .
C Discovery Potential at the Tevatron
The ISAJET 7.44 event generator program [17] with the parton distribution functions of CTEQ3L [18] is employed to calculate the 3# + E / T signal from all possible sources of SUSY particles. An energy resolution of
√ 0.7
E for the hadronic calorimeter and 0.15 √
E for the electromagnetic calorimeter is assumed. Jets are defined to be hadron clusters with E T > 15 GeV in a cone with ∆R ≡ !
∆η 2 + ∆φ 2 = 0.7. Leptons with p T > 5 GeV
18)
In frames (b) and (d) of Figure 65, the Higgs pseudoscalar mass (m
A) and the lighter Higgs scalar mass (m
h) are very sensitive to the value of tan β. For tan β = 48, we obtain m
h# m
A# 103 GeV. For tan β = 50, we find that m
h# m
A# 30 GeV, which have already been excluded by LEP experiments.
130
tan β
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Point A Tau 100%
M 0 60 190
M 1/2 162 170
tan β 3 30
M ( ˜ τ 1 ) 93 95
M ( ˜ χ 0 1 ) 53 65 M ( ˜ χ 0 2 ) 101 122 M ( ˜ χ ± 1 ) 97 122 σ( ˜ χ ± 1 χ ˜ 0 2 )[f b] 947 394
1
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High tan beta SUSY
2) Invariant Mass (GeV/c
0 20 40 60 80 100 120 140 160 180 200
N events
10 102
103
104
2) Invariant Mass (GeV/c
0 20 40 60 80 100 120 140 160 180 200
N events
10 102
103
104
!1
! "
0
! "
2Search for
Data#ee Z
"
"
Z#
$
$ Z#
Dibosons t
t
Goals And Timeline
• Plan to use proven framework created to
maximize sensitivity in different lepton channels.
Already reproducing the framework’s 2 fb -1 results.
Plan:
Winter ‘09: Update existing analysis to ~ 3.5 fb -1 .
Summer ‘09: Add full hadronic tau channels using > 5 fb -1 .
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LHC Era
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What I did last summer...
A big team led by UCD physicists and engineers installed the
Forward Pixel Detector at the very heart of CMS
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The FPIX ready to go
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M. Chertok DOE Site Visit Oct ‘08
LHC kickoff in SF
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(Some of our) CMS
Physics Preparations
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Tau leptons at CMS
UC Davis group central to tau physics preparations at CMS
‣ Triggering, ID, Z-> tau tau, SUSY, Higgs
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Taus at CMS
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Collaboration with LPC and “International CMS”
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Tau Triggering
Previous work: L1 tau
Now working on L2.5 tau trigger efficiency
measurement
3 requirements @ L2.5:
‣ Leading Track within 0.1 Cone
‣ Leading Track p T > 3 GeV
‣ Tracker Isolation with 0.5
Isolation Cone
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Z decays to tau pairs
Critical tuneup for exotics searches
‣ Cross section appreciable -- do with first LHC data
‣ Conway co-leader; ~8 UC Davis people involved!
CDF: Backgrounds directly from data
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Why is this so exciting? 1.15
1.25 1.35 1.30 1.40 1.50
m(!˜
±1,!˜
2o) [GeV]
!˜
2o!˜
2o!˜
±1!˜
2o!˜
+1!˜
"1!˜
2o!˜
2o!˜
+1!˜
2o!˜
"1!˜
2o!˜
1+!˜
1"K(pp – /pp # !˜ 2 o !˜ 2 o , !˜ 1 ± !˜ 2 o , !˜ + 1 !˜ " 1 )
pp
–($S = 2 TeV) pp ($S = 14 TeV)
(a)
100 150 200 250
10 -3 10 -2 10 -1
1 10
100 150 200 250
m(!˜
±1,!˜
2o) [GeV]
: !˜
1o!˜
2o!˜
2o!˜
±1!˜
2o!˜
+1!˜
"1!˜
1o!˜
2o!˜
2o!˜
2o!˜
+1!˜
2o!˜
"1!˜
2o!˜
1+!˜
1"% (pp – /pp # !˜ 1 o !˜ 2 o , !˜ 2 o !˜ 2 o , !˜ 1 ± !˜ 2 o , !˜ 1 + !˜ 1 " ) [pb]
pp ($S = 14 TeV) pp
–($S = 2 TeV)
(b)
53 80 105 129
Figure 3. (a) K-factors for hadroproduction of chargino/neutralino pairs in NLO SUSY QCD, and (b) the NLO cross sections at Tevatron and LHC. The parameters are derived from the mSUGRA point defined in the text, but varying the gaugino mass m 1 /2 ; the factorization/renormalization scale is taken at the average chargino/neutralino mass. The mass at the lower x-axis is identified with the chargino/neutralino mass or the heavier of the chargino/neutralino masses in the pairs. [The ˜ χ + 1 and ˜ χ 0 2 masses nearly coincide.]
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LHC Tevatr
on
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‣ SUSY Low Mass point 1
‣ Chargino+Neutralino decays to trileptons + Missing Et
~40% taus due to light stau
SUSY with taus
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SUSY Trileptons
Keys include
‣ Hadronic tau
triggering and ID
‣ Low electron and muon Pt cuts
‣ Missing Et
‣ Jet veto
‣ Sum Et
‣ Polarization effects?
‣ NN or BDT analysis Signal significance ~2
for 1/fb data
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Technicolor Search
Look for ω T decays to gamma + π T
‣ π T → µµ
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Technicolor Search
ω T →γ + π T , with π T → µµ
Mani Tripathi, John Smith, Carley Kopecky 59
Thoughts on
collaborations
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Collaborations
SLHC discussions are underway
‣ Davis possible interests (timescale 2011-17)
Pixel and/or Silicon strip readout Bump bonding
Semiconductor detector cooling Computing/Simulations
Other?
‣ Physics
Searches (and measurements!) Mostly at high Pt
See what nature shows us in early running
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Collaborations, 2
My Initial thoughts to spark discussions: NTU & UC Davis regarding collider work
‣ Series of videoconferences discussing analysis plans and status
‣ Separate meetings on detector R&D
Definite overlap with neutrino/DM programs
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