1

Bhaskar Dutta

Texas A&M University

Search for DM at the LHC using

Vector Boson Fusion

CETUP: SOUTH DAKOTA

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(i) Cascade Decays of squarks and Dark Matter Search

Outline

(ii) Direct Production Dark Matter Sector at the LHC

Via Vector Boson Fusion

(iii) Conclusion

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LHC and Dark Matter

Usual method to probe these non-colored particles:

LHC is very efficient in producing

colored particles

Annihilation cross-section

of dark matter particles generates dark

matter content of the universe

Annihilation cross-section strength mostly depend on the

colorless particles, e.g., sleptons, staus, charginos, neutralinos, etc.

Cascade decays of squarks and gluinos

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The signal :

jets + leptons+ t’s +W’s+Z’s+H’s + missing ET

Via Cascade decays at the LHC

(or l+l-, t+t-)

DM

DM

Colored particles are

produced and they

decay finally into the

weakly interacting stable

particle

High PT jet

High PT jet

[mass difference is large]

The pT of jets and leptons

depend on the sparticle

masses which are given by

models

R-parity conserving

(or l+l-, t+t-)

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DM at the LHC

Ambitious Goal: Final states Masses Model Parameters

Calculate dark matter density

We may not be able to

solve for masses of all the

sparticles in a model

Solving for the MSSM : Very difficult

0

1~~++ lqQ

0

1~~+ lL

0

1

0

4,3,2~,,~ + llhZ etc.

Identifying one side

is very tricky!

Not all the sparticles

appear in cascade

decays

Problem 1:

Problem 2:

Apply :

Bi-Event Subtraction

Technique (BEST) Dutta, Kamon,

Krislock, ‘12

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1fb 10

-L

1fb 50

-

6 6

Determining Dark Matter Content mSUGRA Non Universal Higgs Model

@ 200 fb-1

1fb 001 -

Mirage Mediation Model

Determine DM content at

14 TeV LHC with high luminosity

Dutta, Kamon, Kolev, Krislock, Oh,

Phys.Rev. D82 (2010) 115009

Dutta, Kamon, Krislock, Sinha, Wang,

Phys.Rev. D85 (2012) 115007

Arnowitt, Dutta, Gurrola, Kamon, Krislock, Toback,

Phys.Rev.Lett. 100 (2008) 231802

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Dark Matter at the LHC

For simple model: the model parameters can be

determined

nature of dark matter candidate

Is the neutralino a Bino, Wino or

Higgsino?

Very difficult to establish!

We need to produce them directly!

For a general model:

(Bino: Smaller annihilation cross-section

Wino/Higgsino: Larger annihilation cross-section)

Are there sleptons around to increase

the annihilation cross-sections?

2. DM via Stop at the LHCLHC

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Utilize Stop decay modes to search charginos, sleptons, neutralinos

Existence and type of DM particle, hard to calculate the DM content

2 jets+ 2 leptons (OSSF-OSDF)

+missing energy

Ex. 3 is mostly Bino-Higgsino

Correct relic density

0

1

For lighter sleptons

Dutta, Kamon, Kolev,Wang, Wu,

Phys. Rev. D 87, 095007 (2013)

Ex. 1 is mostly bino and is wino

Topness variable to identify stops

Stop can identified via fully hadronic or

1 lepton plus multijet final states

Ex. 2 are mostly Higgsino 0

2,1

0

1 0

2

[Yang Bai, Cheng, Gallichio, Gu, 1203.4813;Han,

Katz, Krohn, Reece, 1205.5808;Plehn, Spannowsky,

Takeuchi, 1205.2696;Kaplan, Rehermann, Stolarski,

1205.5816; Dutta, Kamon, Kolev, Sinha, Wang,

1207.1893]

Grasser, Shelton, arXiv:1212.4495

[More in Kuver’s talk]

DM at the LHC Via VBF

9 Dutta, Gurrola, Johns, Kamon, Sheldon, Sinha, Phys. Rev. D 87, 035029 (2013)

Direct probes of charginos, neutralinos and sleptons

P + P

Two high ET forward jets in opposite hemispheres

with large dijet invariant mass

VBF studies

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jjjjjjjjpp0

2

0

2

0

211111~~,~~,~~,~~

jjpp0

1

0

1~~

jjvjjvjjjjjjeepp ~~,~~,~~,~~,~~ ttt

1.

2.

3.

jjttpp 11

~~4. : Kuver’s talk

VBF studies

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jjjjjjjjpp0

2

0

2

0

211111~~,~~,~~,~~

1.

Background: W + jets, Z + jets, WW, ZZ, etc.

Signal: missing energy, ++ t22 j missing energy ++ 22 j

For : 01

021

~,

mmmml

For Heavy Sleptons:

Signal: 2 j + W W, W Z, Z Z + missing energy,

tt

1. Charginos, Neutralinos via VBF

GeV 75 MET GeV; 650)(

0 ;24

GeV 75 )(jp GeV; 50(j)p with jets 2

21

21

1TT

j,jM

.

2 Benchmark Scenarios

30 GeV 30 GeV

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180 GeV

90 GeV 90 GeV

180 GeV

VBF Kinematics

Signal Characteristics:

Large MET, large Mjj, large pT jets

Phys. Rev. D 87, 035029 (2013)

)( 21 j,jMTE

)( 1jpT

GeV 30)()(

GeV 90)(

GeV 180)()(

011

01

021

-t

+

+

~M~M

~M

~M~~M

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Signal: ≥ 2j+2t+missing energy

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2 jets each with pT>50 GeV, leading pT>75 GeV

|(j1,j2)|>4.2, j1j2<0, Mj1j2>650 GeV

TeV

Lum: 25 fb-1

Signal: missing energy

8s

++ t22 j

Two t 's with pT >20 GeV in < 2.1, with R(tt ) > 0:3. All t's are hadronic

The t ID efficiency is assumed to be 55% and the jett Mis-

identification rate is taken to be 1%,

GeV,180~ 021

~~ mm

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Signal: ≥ 2j+2t+missing energy

2.4 s

Signal: ≥ 2j+2+missing energy

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2 jets each with pT>50 GeV, leading pT>75 GeV

|(j1,j2)|>4.2, j1j2<0, Mj1j2>650 GeV

TeV

Lum: 25 fb-1

8s

Signal: missing energy ++ 22 j

Two isolated 's with pT >20 GeV in < 2.1

For 3s :

GeV,180~ 021

~~ mm

GeV330~ 021

~~ mm

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Signal: ≥ 2j+2+missing energy

6 s

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Cross Sections via VBF 2. Lightest neutralinos via VBF jjpp

0

1

0

1~~

CDM

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Cross Sections via VBF 2. Lightest neutralinos via VBF

Pure Wino/Higgsino dark matter scenarios are special

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Cross Sections via VBF

LHC8 LHC14

2. Lightest neutralinos via VBF jjpp

0

1

0

1~~

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Cross Sections via VBF 2. Lightest neutralinos via VBF

Missing ET (GeV)

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Wino-DM MET

Delannoy, Dutta, Gurrola, Johns, Kamon, Luiggi, Melo,Sheldon, Sinha, 1304.7779

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Wino-DM Missing Energy

Delannoy, Dutta, Gurrola, Johns, Kamon, Luiggi, Melo,Sheldon, Sinha, 1304.7779

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Wino-DM MET Preselection:

missing ET > 50 GeV,

2 leading jets (j1,j2) :pT (j1),pT(j2) >30 GeV ,

|(j1, j2)| > 4.2 and j1j2 < 0.

Optimization:

Tagged jets : pT > 50 GeV, Mj1j2 > 1500 GeV;

Events with loosely identified leptons(l = e; ; th) and b-quark jets: rejected.

Missing ET : optimized for different value of the LSP mass.

Jet energy scale uncertainty ~20% change the significance by 4%

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Wino-DM MET

Simultaneous fit of the observed rate,

shape of missing energy distribution:

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Conclusion • Annihilation cross-section of DM particles is mostly

dominated by the particles without any color charge

• These particle are mostly studied from the cascade decays

of new colored particle since direct production is small and

the signal suffers from large background

• We use VBF production of charginos, neutralinos,

sleptons etc. utilizing two high ET jets in opposite

hemispheres

• It is possible to determine the dark matter content with

high accuracy

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Backup

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Sleptons via VBF

Chaudhuri, Datta, Huitu, Konar, Moretti, Mukhopadhyaya hep-ph/0304192

DY

VBF