PDF Recast of SUSY searches in ATLAS and CMS for global fits

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Recast of SUSY searches in ATLAS and CMS for global fits

Isabel Su´arez Fern´andez

Instituto Galego de F´ısica de Altas Enerx´ıas (IGFAE) University of Santiago de Compostela (USC)

October 23, 2017

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Index

1 Introduction Standard Model

Supersymmetry (SUSY)

Minimal Supersymmetric Standard Model (MSSM)

Constrained Minimal Supersymmetric Standard Model (CMSSM)

2 ATLAS SUSY searches Likelihood

Efficiency SM background Exclusion contour

3 CMS SUSY searches

4 Application to CMSSM

5 Conclusions

Isabel Su´arez Fern´andez (USC) October 23, 2017 2 / 37

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Standard Model problems

Gravity

Gravitational interaction isnot included in th SM.

Dark matter and dark energy

Matter described by SM is only around∼4 % from the total energy density of the Universe.

Neutrino mass

SM predictsmassless neutrinos

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Standard Model problems

Gravity

Neutrino mass

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Standard Model problems

Gravity

Neutrino mass

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Indications

The number of fermionic families

Experimentally, three fermionic families have been found.

However, the number of families is not theoretically derivedfrom SM, it is an experimental fact.

Higgs boson mass

In the SM the Higgs boson mass has a quadratic divergence

⇒ m_H ∼ Planck scaleM_Pl '10¹⁸GeV

Experimentally, it is known that this mass is in the electroweak scale. Coupling constats

Interactions coupling constants run with the energy scale. In the SM model the three coupling constants are never unified at once.

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Indications

Higgs boson mass

Experimentally, it is known that this mass is in the electroweak scale.

Coupling constats

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Indications

Higgs boson mass

Experimentally, it is known that this mass is in the electroweak scale.

Coupling constats

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Indications

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How do we fix all this?

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Supersymmetry (SUSY)

What is it?

SUSY is a frameworkto build models⇒ It is not a theory itself!

Where does it come frome?

1 Coleman and Mandula theorem→ Algebra with anticonmmutators

2 Generalization of space-time symmetries

3 Bosons and fermions relation

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Minimal Supersymmetric Standard Model (MSSM)

MSSM

Minimal supersymmetric extension of the SM.

Each SM particle has aSUSY partner particle Higgs extended sector (doublets)

Supertransformations

bosons↔ gauginos fermions↔ sfermions photon↔ photino electron↔ selectron

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Constrained Minimal Supersymmetric Standard Model (CMSSM)

CMSSM

Constrained MSSM phenomenological extension of minimal SuperGravity (mSUGRA), where SUSY is broken by gravity mediation.

Free parameters

m0: Scalar particles masses m_1/2: Gauginos masses A₀: Trillinear couplings

sign(µ): Higgsino mixing parameter

tan(β): Ratio of Higgs doublets vacuum expected values.

tan(β) = ν_u

ν (1.1)

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SUSY: Solves problems

Naturalness

Higgs boson mass doesnot diverge quadratically.

Gravity

Local SUSY needs a curved space-time⇒ Gravity Dark matter and energy

LSP (Lightest Supersymmetric Particle) is adark matter candidate Running coupling constants unificartion

At a certain energy, the coupling constants from different interactions unify at once.

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SUSY: Solves problems

Naturalness

Gravity

Local SUSY needs a curved space-time⇒ Gravity

Dark matter and energy

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SUSY: Solves problems

Naturalness

Gravity

LSP (Lightest Supersymmetric Particle) is adark matter candidate

Running coupling constants unificartion

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SUSY: Solves problems

Naturalness

Gravity

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Unification in SUSY

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MasterCode

MasterCode Collaboration

Collaboration ^a whose computer code allows to fit different versions of the Minimal Supersymmetric Standard Model (MSSM) to currently existing experimental data.

aE. Bagnaschi, K. Sakurai M. Borsato, O. Buchmueller, R. Cavanaugh , V. Chobanova, M. Citron, J. Costa, A. De Roeck, M.J. Dolan, J.R. Ellis, H. Flacher, S. Heinemeyer, G. Isidori, M. Lucio, D. Mart´ınez Santos, K.A. Olive, A. Richards, I. Su´arez Fern´andez, G. Weiglein

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ATLAS and CMS direct SUSY searches at √

s = 13 TeV

ATLAS & CMS

Direct SUSY searches in a simplified model at √

s = 13 TeV.

LHC Recast

Building a code to recast these ATLAS and CMS searches in other SUSY models.

What do we do?

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ATLAS and CMS direct SUSY searches at √

s = 13 TeV

ATLAS & CMS

s = 13 TeV.

LHC Recast

What do we do?

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ATLAS and CMS direct SUSY searches at √

s = 13 TeV

ATLAS & CMS

s = 13 TeV.

LHC Recast

What do we do?

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Procedure → Example of ATLAS simplified model

Final states with jets and two same-sign leptons three leptons at

√s = 13 TeV [1]

m( ˜χ⁰₂) = ¹₂m(˜g) +¹₂m( ˜χ⁰₁) , m(˜l/˜ν) = ¹₄m(˜g) +³₄m( ˜χ⁰₁) m(˜g),m( ˜χ⁰₁) → Inputs

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Procedure→ Likelihood (ATLAS)

Poisson distribution

We start from a Poisson distribution L_Poisson(N_obs|S_exp) = 1

N_obs!e^−(S^exp^+b)(b+Sexp)^N^obs (2.1)

Gaussian distribution for background We assume a gaussian distribution forb

L_b= exp

"

−1 2

b−b₀ σ(b)

2#

(2.2)

Total Likelihood

L(N_obs|b,S_exp) =L_PoissonL_b (2.3)

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Procedure→ Likelihood (ATLAS)

Poisson distribution

We start from a Poisson distribution L_Poisson(N_obs|S_exp) = 1

N_obs!e^−(S^exp^+b)(b+Sexp)^N^obs (2.1) Gaussian distribution for background

We assume a gaussian distribution forb

L_b= exp

"

−1 2

b−b₀ σ(b)

2#

(2.2)

Total Likelihood

L(N |b,S ) =L L (2.3)

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Procedure → Likelihood profiling (ATLAS)

Likelihood

L(N_obs|b,S_exp) = 1

N_obs!e^−(S^exp^+b)e⁻

1 2

_b−b

0 σ(b)

2

(b+S_exp)^N^obs (2.4)

Maximizing

∂L(N_obs|b,S_exp)

∂b = 0 (2.5)

Analytical solution

bˆ=

b₀−Sexp−σ²(b)

2 +1

2

b₀−S_exp−σ²(b)₂ + 4

σ²(b)N_obs−S_expσ²(b) +S_expb₀¹

2 (2.6)

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Procedure → Likelihood dependence(ATLAS)

Profiled Likelihood

b →bˆ ⇒ L(N_obs|b,Sexp)→ L(N_obs|S_exp) (2.7) N_obs Number of observed events

b₀: Central value of b, the expected SM background σ(b): Uncertainty of b

S_exp: Expected SUSY signal: S_exp =σεL

σCross-section→σ(m(˜g),m( ˜χ⁰₁)) εEfficiency→ε(m(˜g),m( ˜χ⁰₁)) LLuminosity→Constant

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Procedure → Likelihood dependence(ATLAS)

Profiled Likelihood

b →bˆ ⇒ L(N_obs|b,Sexp)→ L(N_obs|S_exp) (2.7) N_obs Number of observed events

b₀: Central value of b, the expected SM background σ(b): Uncertainty of b

S_exp: Expected SUSY signal: S_exp =σεL σCross-section→σ(m(˜g),m( ˜χ⁰₁)) εEfficiency→ε(m(˜g),m( ˜χ⁰₁)) LLuminosity→Constant

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Procedure → Efficiency

Simulating the efficiency

1 Inputs: m(˜g), m( ˜χ⁰₁)

2 Pythia 8.2: Simulatespp collisions, events generator.

3 Delphes 3: Simulates the ATLAS detector.

4 Signal Regions: Conditions for events are defined.

5 Selection: Events not satisfying the requirements are discarded.

6 Efficiency: ε= Final events Total events

Figure:Signal Regions from [1] arXiv:1602.09058v2 [hep-ex]

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Procedure → Efficiency

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Procedure → Efficiency

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Procedure → Efficiency

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Procedure → Efficiency

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Procedure → Efficiency

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Standard Model Background

SM contributions

SM processes that mimic the final state contribute. We use background data given by [1].

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Standard Model Background

SM contributions

SM processes that mimic the final state contribute. We use background data given by [1].

Figure: SM Background from [1] arXiv:1602.09058v2 [hep-ex]

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Procedure → Exclusion contours

Exclusion contours

The procedure explained is applied for a wide range of input masses in the plane (m(˜g),m( ˜χ⁰₁)). With this we can reproduce the ATLAS plots with theχ² probability.

200 400 600 800 1000 1200 1400 1600

mg˜[GeV]

200 400 600 800 1000 1200 1400

m˜χ

0 1[GeV]

atlas_1602_09058

˜g→qq(ll/νν) ˜χ⁰1

LHC_recast w. MC-err ATLAS w. theo-err

10^-3 10^-2 10^-1 10⁰

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ATLAS topologies

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Other ATLAS analyses

500 1000 1500 2000

mg˜[GeV]

500 1000 1500

m˜χ 0 1[GeV]

atlas_1706_03731

˜ g→qqWZ˜χ⁰1

10^-15 10^-14 10^-13 10^-12 10^-11 10^-10 10^-9 10^-8 10^-7 10^-6 10^-5 10^-4 10^-3 10^-2 10^-1

500 1000 1500 2000

m

500 1000 1500

m˜χ 0 1[GeV]

atlas_1706_03731

˜ g→qq(ll/νν) ˜χ⁰1

10^-15 10^-14 10^-13 10^-12 10^-11 10^-10 10^-9 10^-8 10^-7 10^-6 10^-5 10^-4 10^-3 10^-2 10^-1

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CMS topologies

Figure:CMS topologies from [3] arXiv:1705.04650 [hep-ex]

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Procedure → Likelihood (CMS)

Likelihood

L_Poisson(N_obs|S_exp) = 1

N_obs!e^−(S^exp^+b)(b+Sexp)^N^obs (3.1) SM background

The 213 Signal Regions are correlated → Correlation matrixfrom [3]

Fit

We obtain theχ² probability trough a fit using the correlation matrix [3] arXiv:1705.04650 [hep-ex]

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Other CMS analyses

[GeV]

g~

m 600 800 1000 1200 1400 1600 1800 2000 2200 [GeV]01χ∼m

0 200 400 600 800 1000 1200 1400 1600 1800 2000

−4 10

−3 10

−2 10

−1 10 1 (13 TeV)

35.9 fb-1

CMS Preliminary NLO+NLL exclusion 1 χ∼0 b

→ b g~ , g~ g~

→ pp

theory σ

± 1 Observed

experiment σ

± 1 Expected

95% CL upper limit on cross section [pb]

500 1000 1500 2000

mg˜[GeV]

0 200 400 600 800 1000 1200 1400 1600

m˜χ 0 1[GeV]

cms_1705_04650

˜g→bb˜χ⁰1

10^-3 10^-2 10^-1 10⁰

[GeV]

g~

m 600800 1000 1200 1400 1600 1800 2000 2200 [GeV]0 1χ∼m

0 200 400 600 800 1000 1200 1400 1600 1800

−3 10

−2 10

−1 10 1 (13 TeV)

35.9 fb-1

CMS Preliminary NLO+NLL exclusion 1 χ∼0 q

→ q g~ , g~ g~

→ pp

theory σ

± 1 Observed

experiment σ

± 1 Expected

95% CL upper limit on cross section [pb]

500 1000 1500 2000

m˜g[GeV]

0 200 400 600 800 1000 1200 1400 1600

m˜χ 0 1[GeV]

cms_1705_04650

˜g→qq˜χ⁰1

10^-3 10^-2 10^-1 10⁰

Figure: [3] arXiv:1705.04650 [hep-ex]

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Other analyses I

Implemented

Paper/Conference Note Number of SR

ATLAS 1602.09058 4

ATLAS 1605.04285 6

ATLAS 1706.03731 13

CMS 1705.04650 213

Total 236

In process

Paper/Conference Note Number of SR

ATLAS-CONF-2017-039 37

Total 45

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Application to CMSSM I

Exclusion contour

We apply our algorithm in the CMSSM

We plot an exclusion contour in the (m₀,m_1/2) plane

Previous best-fit-point

To study the masses plane we fix the other parameters totheir previous best-fit-point value

A0 =−3440 tan(β) = 21 sign(µ)>0

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Application to CMSSM II

Exclusion contour

Low energy region is excluded

The new best-fit should be at higher energies

The new restriction is stronger than the previous one

(a) Previous MasterCode result [4] (b) LHC Recast

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Summary

Direct ATLAS and CMS SUSY searches

We developed a code to analyse ATLAS and CMS SUSY simplified models

In these simplifications we are able to reproduce the mass constraints using our code

We can recast these ATLAS and CMS searches in other supersymmetric models

CMSSM pMSSM NUHM

Results → CMSSM

In the (m₀,m_1/2) plane, the low energy region is excluded

The new restriction we obtained using searches at 13 TeV is stronger than the previous one at 7 TeV

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Summary

Direct ATLAS and CMS SUSY searches

We developed a code to analyse ATLAS and CMS SUSY simplified models

In these simplifications we are able to reproduce the mass constraints using our code

We can recast these ATLAS and CMS searches in other supersymmetric models

CMSSM pMSSM NUHM

Results → CMSSM

In the (m₀,m_1/2) plane, the low energy region is excluded

The new restriction we obtained using searches at 13 TeV is stronger

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Conclusions

SUSY is a framework that might solve the SM problems.

Our code can predict the energy scales where SUSY is more likely to exist.

We are able to define the energy scales where future accelerators should work.

In case of finding SUSY, these recasts can be used as inputs to fit other SUSY models and find the one that better describes our Universe.

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Conclusions

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Conclusions

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Conclusions

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Thanks

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BACKUP

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Flavour observables

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Previous best fit point

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Effective mass

m_eff =

Nlepton

X

i=1

p_T,i^lepton+

Njets

X

j=1

p_T,j^jets+E_T^miss (5.1)

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Superpartners

Fields Symbols Spin

Sleptons e˜L, e˜R , µ˜L, µ˜R , τ˜L, ν˜e , ν˜µ, ν˜τ 0

Squarks q˜L, q˜R 0

Neutralinos B˜⁰ , W˜⁰ , H˜_u⁰ , H˜_d⁰ 1/2 Charginos W˜^±, H˜_u^±, H˜_d^± 1/2

Gluinos g˜ 1/2

Goldstino or gravitino G˜ 3/2

Table:Superpartners of SM particles

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