Maxwell Chertok UC Davis

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Exotics with Dileptons and

More

Maxwell Chertok UC Davis

From LHC to the Universe National Taiwan University

Taipei, Dec. 2008

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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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M. Chertok NTU-UC Davis Workshop

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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M. Chertok NTU-UC Davis Workshop

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

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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

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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 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

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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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%

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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...

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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

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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

±1

χ ˜

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

M. Chertok NTU-UC Davis Workshop

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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

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High tan beta SUSY

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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

! "

2

Search 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 .

M. Chertok NTU-UC Davis Workshop

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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 o2 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 o2 o , !˜ 2 o2 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

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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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Suggestion

Schedule video conference in

near future (Jan ’09 ?) to allow

NTU CMS group to fill in UC Davis group

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Figure

Updating...

References

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