dark matter at the lhc

12/17/07Cosmological Connection at the LHC: Stau N

eutralino Coannihilation Case

Dark Matter Dark Matter at the at the LHCLHC

Bhaskar Dutta

Texas A&M University

Dark Matter at the LHC 130th Oct ’ 09

Texas Cosmology Network Meeting, UT, Austin

2

2

1CDM

+ ….

Dark Matter and SUSYDark Matter and SUSY

pbM

vann 1~~2

2

Dark Matter at the LHC

We need to observe the new layer of matter in order to establish this explanation

The signal : jets + leptons + missing ET

SUSY at the LHC

(or l+l-, )

DM

DM

Colored particles get produced and decay into weakly interacting stable particles

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

3

(or l+l-, )


mSUGRA: Minimal ScenariomSUGRA: Minimal Scenario

4 parameters + 1 sign

du

Zdu

HHW

MA

Mm

Mm

MH/H

in of Sign :)sign(

at coupingTrilinear :

at massscalar Common :

at mass gaugino Common :

at :tan

(2)GUT0

GUT0

GUT1/2

Dark Matter at the LHC 44

Minimal Supersymmetry Standard Model has more than 100 parameters

•We may not have enough observables to establish them

•We start with a simple scenario and go to complicated cases

SUSY ModelsSUSY Models

Dark Matter Allowed RegionsDark Matter Allowed Regionstan = 40

A0 = 0, > 0

ab

c

Excluded by1)Rare B decay b s 2)No CDM candidate3)Muon magnetic moment

a

bc

m0 (

GeV

)

m1/2 (GeV)

Over-dense DM Region22

Coannihilation Region11

FP/HB Region33


Observables at the LHC Observables at the LHC

Mj

&Mj

Lu~

01χ~

02χ~

g~

97%

u

u

SU

SY

Mass

es

(CDM)

pT

> 40 GeV

pT > 20 GeV

ET jet > 100 G

eV

M

& pT()

1~

100%

The observables include:Z, h, W, , t, b, jet, l and missing energy

The observables are determined by the underlying physics of the model


CaseCase 1. Coannihilation Region1. Coannihilation Region

100% 1~

Lu~

01χ~

02χ~

g~

97%

u

u

SU

SY

Mass

es

(CDM)2 quarks+2 ’s

+missing energy

7

Low energy taus characterize the CA region

However, one needs to measure the model parameters to predict thedark matter content in this scenario


fTMe k/Δ

2

GeV15~5Δ 011

~~ MMM GeV15~5Δ 0

11~~ MMM

01~

1~

+ ….

Griest, Seckel ’91

Arnowitt, Dutta, Kamon,Toback’08

Determining mSUGRA ParametersDetermining mSUGRA ParametersSolved by inverting the following functions:

140tan

160

4350

5210

0

2/1

0

A

m

m

),tan,( 02/102

~01

AmmZh

1fb 10 L

1fb 50

)fb 70( %1.4

)fb 30( %2.6/1

12~

2~ 0

101

hh

),tan,,(

),(

),tan,,(

),(

002/14peak )(

eff

02/13peakeff

002/12peak

02/11peak

AmmXM

mmXM

AmmXM

mmXM

b

j

10 fb-1

Dark Matter at the LHC 88Phys.Rev.Lett.100:231802,2008.

Case 2 : Over-dense regionCase 2 : Over-dense region

1~

Lu~

01χ~

02χ~

g~

h

1χ~

m1/2=440, m0=471, tan=40, mtop=175

Re~

u

87%

10411044

500

393

181

341

114

46213%

Z91

ETmiss > 180 GeV;

N(jet) > 2 with ET > 200 GeV; ET

miss + ETj1 + ET

j2 > 600 GeV


N(b) > 2 with PT > 100 GeV; 0.4< Rbb < 1

DeterminingDetermining hh22

Solved by inverting the following functions:

1839tan

950

15440

50472

0

21

0

A

m

m

/

),tan,( 02/102

~01

AmmZh 1fb 1000 L

%~h/h ~~ 150ΩΩ 2201

01

)tan(

)tan(

)(

)(

00214peak )(

eff

00213peak )(

eff

0212peakeff

0211point end

A,,m,mXM

A,,m,mXM

m,mXM

m,mXM

/bb

/b

/

/jbb

1000 fb1000 fb-1-1


Phys.Rev.D79:055002,2009 Dutta, Kamon,Nanopoulos etal ’09

Case 3 : Focus Point /HBCase 3 : Focus Point /HB

Prospects at the LHCProspects at the LHC: A few mass measurements are available: 2nd and 3rd neutralinos, and gluino

g~

0i

~

q~ l~ Z

ZZ

Z

m0, A0, , tan

m1/2, tan


0

0

0

0

2

1

0

scMssM

ccMcsM

scMccMM

ssMcsMM

WZWZ

WZWZ

WZWZ

WZWZ

~Μ M4x4 (m1/2, , tan)

01

02

21 ~~ MMD 01

03

31 ~~ MMD g~M

)tan( 212

01

,,mZh /~

Case 4 : Non-U SUGRACase 4 : Non-U SUGRANature may not be so kind …Nature may not be so kind … Our studies have been done based on a minimal scenario (= mSUGRA). … … Let’s consider a non-universal scenario: Higgs non-universality: mHu, mHd m0

Steps:Steps:1) Reduce Higgs coupling parameter, , by increasing 2) mHu, … More annihilation (less abundance) correct values of h2

3) Find smoking gun signals Technique to calculate h2

SUGRA Models at the LHC 1212


Extraction of Model ParametersExtraction of Model Parameters

End-points-nonuniversalM(jW) [ ] = 714.6 GeVM(jW) [ ] = 727.3 GeV[use 2 ’s since ]M(jW)[ ] = 652.4 GeV [use Z since ]M(jW) [ ] = 738.6 GeV

22 32

0

4

10

02

We can use stop decay chainIn this case we use a b/t

We have 3 (4) parameters in the chargino-neutralino system:m1/2, , tan (m1,m2, , tan)

01

02 Z

Theory:738.8

~500 GeV

M(bW)

M(jW)

Similarly, M(tZ) =338 GeV00

3

Mt, Mj etc can also be constructed


ConclusionSignature contains missing energy (R parity conserving) many jets and leptons : Discovering SUSY should not be a problem!

Once SUSY is discovered, attempts will be made to measure the sparticle masses (highly non trivial!), establish the model and make connection between particle physics and cosmology

Different cosmologically motivated regions of the minimal model have distinct signatures.It is possible to determine model parameters and the relic density based on the LHC measurements


Work is in progress to determine non-universal model Parameters----looks promising

dark matter at the lhc

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