The MSSM after two years of LHC running Felix Brmmer DESY Felix - - PowerPoint PPT Presentation

The MSSM after two years of LHC running

Felix Brümmer DESY

Felix Brümmer MSSM status 1 / 14

The Standard Model

Felix Brümmer MSSM status 2 / 14

Beyond the Standard Model: The MSSM

Felix Brümmer MSSM status 3 / 14

Beyond the Standard Model: The MSSM

minimal SUSY extension of Standard Model two Higgs doublets a scalar s-particle for every SM fermion: squarks, sleptons a fermionic particl-ino for every SM boson: gauginos, higgsinos → charginos χ±, neutralinos χ0 O(100) parameters

Felix Brümmer MSSM status 3 / 14

Restricting the parameter space

L✘✘ ✘

SUSY = − 1

2

• a

Ma λaλa + h.c. − m2

Hu h† uhu − m2 Hd h† dhd

− m2

Q

Q† Q − m2

U

U† U − m2

D

D† D − m2

L

L† L − m2

E

E† E −

• AUyu

Q Uhu + ADyd Q Dhd + AEye L Ehd + Bµhuhd

• + h.c.

Felix Brümmer MSSM status 4 / 14

Restricting the parameter space

L✘✘ ✘

SUSY = − 1

2

• a

Ma λaλa + h.c. − m2

Hu h† uhu − m2 Hd h† dhd

− m2

Q

Q† Q − m2

U

U† U − m2

D

D† D − m2

L

L† L − m2

E

E† E −

• AUyu

Q Uhu + ADyd Q Dhd + AEye L Ehd + Bµhuhd

• + h.c.

Benchmark scenarios: e.g. CMSSM: M1/2, m0, A0, tan β, sgn(µ) Convenient; self-consistent; not well motivated theoretically Do not expect the world to be anywhere close to mSUGRA

Felix Brümmer MSSM status 4 / 14

Restricting the parameter space

L✘✘ ✘

SUSY = − 1

2

• a

Ma λaλa + h.c. − m2

Hu h† uhu − m2 Hd h† dhd

− m2

Q

Q† Q − m2

U

U† U − m2

D

D† D − m2

L

L† L − m2

E

E† E −

• AUyu

Q Uhu + ADyd Q Dhd + AEye L Ehd + Bµhuhd

• + h.c.

Benchmark scenarios: e.g. CMSSM: M1/2, m0, A0, tan β, sgn(µ) Convenient; self-consistent; not well motivated theoretically Do not expect the world to be anywhere close to mSUGRA Simplified models: truncate to a few states relevant for specific signatures good starting point for phenomenology; exclusion bounds often too strong related: pMSSM, 19 TeV-scale parameters

Felix Brümmer MSSM status 4 / 14

Restricting the parameter space

L✘✘ ✘

SUSY = − 1

2

• a

Ma λaλa + h.c. − m2

Hu h† uhu − m2 Hd h† dhd

− m2

Q

Q† Q − m2

U

U† U − m2

D

D† D − m2

L

L† L − m2

E

E† E −

• AUyu

Q Uhu + ADyd Q Dhd + AEye L Ehd + Bµhuhd

• + h.c.

Benchmark scenarios: e.g. CMSSM: M1/2, m0, A0, tan β, sgn(µ) Convenient; self-consistent; not well motivated theoretically Do not expect the world to be anywhere close to mSUGRA Simplified models: truncate to a few states relevant for specific signatures good starting point for phenomenology; exclusion bounds often too strong related: pMSSM, 19 TeV-scale parameters Full models: Where to start? Realistic, but usually more intricate than needed for LHC Exclusion bounds not easily transferrable

Felix Brümmer MSSM status 4 / 14

Sparticle production and decays

R-parity ⇒ sparticles produced pairwise at hadron collider: mainly ˜ q˜ g, ˜ q˜ q, ˜ q˜ q∗, ˜ g˜ g typical decay signature: cascade decays into lightest SUSY particle ⇒ MET + jets (+ leptons)

q ~ q ~ g ~ q ~ e ν W χ χ χ q q q g q + +

Felix Brümmer MSSM status 5 / 14

Constraints I: Direct sparticle searches

Stringent limits on first-generation squark and gluino masses:

→ ATLAS-CONF-2012-037

At m˜

u1 ≈ m˜ d1 ≈ M˜ g:

all 1.4 TeV Beware: model dependence! more general pMSSM analysis:

→ Sekmen et al. ’11 @ 1 fb−1

Felix Brümmer MSSM status 6 / 14

Constraints II: A 125 GeV Higgs

Further constraints on stop sector: Suppose a SM-like Higgs is at mh0 = 125 ± 2 GeV mh0 > mZ needs large loop contributions (from large stop masses/mixings) m2

h0 = m2 Z +

3 4π2 y4

t v2

• log

m2

˜ t

m2

t

+ A2

t

m2

˜ t

• 1 −

A2

t

12 m2

˜ t

• + . . .

1252 = 912 + 862

→ FB/Kraml/Kulkarni, in progress

Needs m˜

t 2 TeV,

heavy stops

• r large |At/m˜

t| ≈ 2,

“maximal stop mixing”

Felix Brümmer MSSM status 7 / 14

Fine-tuning I: The Little Hierarchy

m2

Z = −2(m2 Hu + |µ|2)

µ = Higgsino mass, m2

Hu = up-type Higgs soft mass (< 0 by EWSB)

mHu, m˜

t, M˜ g generically of similar magnitude m✘✘

✘

SUSY

therefore mZ ∼ m✘✘ ✘

SUSY unless

large cancellation between |µ|2 and m2

Hu, or

|mHu| ≪ m✘

✘

SUSY accidentally at the weak scale (and µ small)

Either way: fine-tuning of parameters needed for mZ ≪ m✘✘ ✘

SUSY

Generic: mZ ∼ m✘✘ ✘

SUSY

Fine-tuned: mZ ≪ m✘✘ ✘

SUSY

Felix Brümmer MSSM status 8 / 14

Fine-tuning II: Neutralino dark matter

Bino relic density too large: need ˜ τ or ˜ t coannihilation resonant h0 or A0 exchange some higgsino admixture (focus point) 0 < m0 < 5 TeV, 5 < m0 < 20 TeV

→ Baer, Barger, Mustafayev ’12

Felix Brümmer MSSM status 9 / 14

Fine-tuning II: Neutralino dark matter

Bino relic density too large: need ✭✭✭✭✭✭✭✭✭ ˜ τ or ˜ t coannihilation ✭✭✭✭✭✭✭✭✭✭✭✭ ✭ resonant h0 or A0 exchange some higgsino admixture (focus point) (?) 0 < m0 < 5 TeV, 5 < m0 < 20 TeV

→ Baer, Barger, Mustafayev ’12

Felix Brümmer MSSM status 9 / 14

Fine-tuning II: Neutralino dark matter

Bino relic density too large: need ✭✭✭✭✭✭✭✭✭ ˜ τ or ˜ t coannihilation ✭✭✭✭✭✭✭✭✭✭✭✭ ✭ resonant h0 or A0 exchange some higgsino admixture (focus point) (?) 0 < m0 < 5 TeV, 5 < m0 < 20 TeV

→ Baer, Barger, Mustafayev ’12

Caution: this is just for CMSSM Still “WIMP miracle” losing some of its appeal (SUSY doesn’t need thermal WIMPs. Gravitinos, axinos, nonthermally produced higgsinos? . . . )

Felix Brümmer MSSM status 9 / 14

Natural SUSY

Idea: keep states related to naturalness “light” → Papucci/Ruderman/Weiler ’11 µ, mHu, m˜

t1, m˜ t2, m˜ bL, (M˜ g) 1 TeV

first-generation squarks ≫ 1 TeV

• W- and

B-like χ±, χ0 undetermined direct ˜ q, ˜ g search bounds evaded Higgs mass still problematic LHC should find higgsinos, ˜ t, ˜ b, (˜ g)

H ~ g ~ t t ~ ~ b ~

L L R

everything else

Felix Brümmer MSSM status 10 / 14

Natural SUSY

Idea: keep states related to naturalness “light” → Papucci/Ruderman/Weiler ’11 µ, mHu, m˜

t1, m˜ t2, m˜ bL, (M˜ g) 1 TeV

first-generation squarks ≫ 1 TeV

• W- and

B-like χ±, χ0 undetermined direct ˜ q, ˜ g search bounds evaded Higgs mass still problematic LHC should find higgsinos, ˜ t, ˜ b, (˜ g)

H ~ g ~ t t ~ ~ b ~

L L R

everything else

Comments: Phenomenological ansatz: soft terms prescribed at TeV scale Not clear a priori if realizable in a UV-scale model Some proposals: → Craig/McCullough/Thaler, Craig/Dimopoulos/Gherghetta,

Krippendorf/Nilles/Ratz/Winkler, Csaki/Randall/Terning, Larsen/Nomura/Roberts. . .

Felix Brümmer MSSM status 10 / 14

Heavy stops

Idea: Maybe heavy stops can be reconciled with naturalness mZ ≪ m✘✘ ✘

SUSY due to model relations between soft terms

Prototype: Focus point → Chan/Chattopadhyay/Nath ’97, Feng/Matchev/Moroi ’99 Natural to have m0 ≫ TeV in CMSSM Nice explanation for dark matter relic density

Felix Brümmer MSSM status 11 / 14

Heavy stops

Idea: Maybe heavy stops can be reconciled with naturalness mZ ≪ m✘✘ ✘

SUSY due to model relations between soft terms

Prototype: Focus point → Chan/Chattopadhyay/Nath ’97, Feng/Matchev/Moroi ’99 Natural to have m0 ≫ TeV in CMSSM Nice explanation for dark matter relic density (?) Experiment now requires M˜

g 1 TeV

··

⌢

Felix Brümmer MSSM status 11 / 14

Heavy stops

Idea: Maybe heavy stops can be reconciled with naturalness mZ ≪ m✘✘ ✘

SUSY due to model relations between soft terms

Prototype: Focus point → Chan/Chattopadhyay/Nath ’97, Feng/Matchev/Moroi ’99 Natural to have m0 ≫ TeV in CMSSM Nice explanation for dark matter relic density Experiment now requires M˜

g 1 TeV

··

⌢

Variations: non-universal gaugino masses contributing to mZ ≪ m✘✘ ✘

SUSY

→ Abe/Kobayashi/Omura ’07, Horton/Ross ’09, FB/Buchmüller ’11, ’12, Younkin/Martin ’12

Potentially all superparticles heavy (except higgsinos?) Difficult to test at LHC

H ~ everything else

Criticism: high sensitivity to dimensionless (Yukawa, gauge) couplings

→ Romanino/Strumia ’99

Felix Brümmer MSSM status 11 / 14

Large stop mixing

L✘✘ ✘

SUSY = −Atyt ˜

tL˜ tRhu + h.c. + . . .

→ Arbey/Battaglia/Djouadi/Mahmoudi/Quevillon

Xt = At − µ cot β: stop mixing parameter |Xt/m˜

t| ≈ 2 at TeV scale

⇒ large mh0 possible Non-trivial to get this from a model

→ Draper et al. ’11, Aparicio/Cerdeño/Ibañez ’12, FB/Kraml/Kulkarni, in progress, . . .

e.g. gauge mediation or AMSB: no way (so far)

Felix Brümmer MSSM status 12 / 14

Signatures from unusual spectra

Compressed spectra: Squarks and gluinos in reach but hidden

→ Conley et al. ’11, LeCompte/Martin ’11, . . .

CMSSM searches assume m˜

g : mχ0

1 ≃ 6 : 1

Smaller ∆m ⇒ low cut efficiencies Also a concern for very long decay chains Maybe we have produced lots of gluinos already without seeing them

Felix Brümmer MSSM status 13 / 14

Signatures from unusual spectra

Compressed spectra: Squarks and gluinos in reach but hidden

→ Conley et al. ’11, LeCompte/Martin ’11, . . .

CMSSM searches assume m˜

g : mχ0

1 ≃ 6 : 1

Smaller ∆m ⇒ low cut efficiencies Also a concern for very long decay chains Maybe we have produced lots of gluinos already without seeing them Split spectra: Only Higgsinos accessible Higgsinos with EW-scale masses produced abundantly, e.g. in Drell-Yan Small mass splittings ⇒ soft decay products ⇒ signal buried under BG

→ Baer/Barger/Huang ’11, Bobrovskyi/FB/Buchmüller/Hajer ’11

Monojets (from ISR) + MET? Displaced vertices/charged tracks from long-lived charginos?

Felix Brümmer MSSM status 13 / 14

Summary

LHC searches constrain the MSSM:

no signal in jets + MET (+ leptons) ⇒ 1st gen. squarks and gluinos heavy mh ≈ 125 GeV ⇒ stops heavy, or large stop mixing

Felix Brümmer MSSM status 14 / 14

Summary

LHC searches constrain the MSSM:

no signal in jets + MET (+ leptons) ⇒ 1st gen. squarks and gluinos heavy mh ≈ 125 GeV ⇒ stops heavy, or large stop mixing

Minimal toy scenarios (CMSSM, GMSB, AMSB) severly under pressure (but why care: not realistic anyway)

Felix Brümmer MSSM status 14 / 14

Summary

LHC searches constrain the MSSM:

no signal in jets + MET (+ leptons) ⇒ 1st gen. squarks and gluinos heavy mh ≈ 125 GeV ⇒ stops heavy, or large stop mixing

Minimal toy scenarios (CMSSM, GMSB, AMSB) severly under pressure (but why care: not realistic anyway) No model ruled out. Just getting uglier: TeV-scale soft terms need large fine-tuning

Felix Brümmer MSSM status 14 / 14

Summary

LHC searches constrain the MSSM:

no signal in jets + MET (+ leptons) ⇒ 1st gen. squarks and gluinos heavy mh ≈ 125 GeV ⇒ stops heavy, or large stop mixing

Minimal toy scenarios (CMSSM, GMSB, AMSB) severly under pressure (but why care: not realistic anyway) No model ruled out. Just getting uglier: TeV-scale soft terms need large fine-tuning Interesting models:

with states related to naturalness still “light” → natural SUSY approach

• r naturally allowing m✘

✘

SUSY ≫ mEW → focus point approach

Felix Brümmer MSSM status 14 / 14

Summary

LHC searches constrain the MSSM:

no signal in jets + MET (+ leptons) ⇒ 1st gen. squarks and gluinos heavy mh ≈ 125 GeV ⇒ stops heavy, or large stop mixing

Minimal toy scenarios (CMSSM, GMSB, AMSB) severly under pressure (but why care: not realistic anyway) No model ruled out. Just getting uglier: TeV-scale soft terms need large fine-tuning Interesting models:

with states related to naturalness still “light” → natural SUSY approach

• r naturally allowing m✘

✘

SUSY ≫ mEW → focus point approach

Maximal stop mixing helps with mh0, but hard to realize in realistic models

Felix Brümmer MSSM status 14 / 14

Summary

LHC searches constrain the MSSM:

no signal in jets + MET (+ leptons) ⇒ 1st gen. squarks and gluinos heavy mh ≈ 125 GeV ⇒ stops heavy, or large stop mixing

Minimal toy scenarios (CMSSM, GMSB, AMSB) severly under pressure (but why care: not realistic anyway) No model ruled out. Just getting uglier: TeV-scale soft terms need large fine-tuning Interesting models:

with states related to naturalness still “light” → natural SUSY approach

• r naturally allowing m✘

✘

SUSY ≫ mEW → focus point approach

Maximal stop mixing helps with mh0, but hard to realize in realistic models Experiments: look out for

direct stop / sbottom production light higgsinos (Monojets + MET? Chargino tracks?) compressed spectra jets + MET (+leptons), but this time please find something!

Felix Brümmer MSSM status 14 / 14