SUPERSYMMETRY.pdf

7/27/2019 SUPERSYMMETRY.pdf

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SUPERSYMMETRY:

WHERE DO WE STAND?Matthew Reece

Harvard University

At LHCP, Barcelona, May 16, 2013


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WHY SUPERSYMMETRY?

Naturalness

Gauge Coupling Unification

Dark MatterRecent experimental results make this lookshakier than before....(This is a review talk; apologies for omissions and idiosyncracies)


3/29

NATURAL SUSY, 1984From Lawrence Halls talk at SavasFest

Text

W boson near

the top of thespectrum....

1984 was a

utopian yearfor SUSY.

Times have

changed!


4/29

125 GEV HIGGS AND SUSY


5/29


Very interesting! Light enough that SUSY stillseems sane, but heavy enough that manymodels dont.

MSSM:

m2h = m2

Zc2

2

+3m4t42v2

log

M2

S

m2t

+X2tM2

S

1

X2t12M2

S

h h

t

+h h

t

Haber, Hempfling 91

more: Haber, Hempfling, Hoang, Ellis, Ridolfi, Zwirner, Casas, Espinosa, Quiros, Riotto,Carena, Wagner, Degrassi, Heinemeyer, Hollik, Slavich, Weiglein


6/29


m2h = m2

Zc2

2

+3m4t42v2

log

M2

S

m2t

+X2tM2

S

1

X2t12M2

S

Haber, Hempfling 91


Tree-level bound: 90 GeV


MSSM:h h

t

+h h

t


7/29


m2h = m2

Zc2

2

+3m4t42v2

log

M2

S

m2t

+X2tM2

S

1

X2t12M2

S

Haber, Hempfling 91



MSSM:h h

t

+h h

t

Logarithmic growth with stop mass


8/29


m2h = m2

Zc2

2

+3m4t42v2

log

M2

S

m2t

+X2tM2

S

1

X2t12M2

S

Haber, Hempfling 91



MSSM:h h

t

+h h

t

Polynomial growth withXt, a mixing

between left- and right- handed stops.


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1 2 5 10 20 50 100

105

110

115

120

125

130

135

MS TeV

mh

GeV

6 4 2 0 2 4 6

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Xt TeV

MS

TeV

P. Draper, P. Meade, MR, D. Shih 11; similar work by many others

In the MSSM, a 125 GeV Higgs requires large quantumcorrections, with multi-TeV SUSY-breaking parameters,

reintroducing (part of) the hierarchy.

lifting theHiggs mass

needs ~ 5

to 10 TeVscalar

masses

or few TeV trilinearHiggs-stop-stop coupling

high-scale SUSY


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NATURALNESS

h h

t

h h

t

+h h

t

Higgs potential -2|H|2+|H|4: large quantum correctionsto the mass2 term. Direct searches constrain them:

m2Hu =

382 y

2t

m2tL +m2tR + |At|

2log

TeV .

Either the stop is light, or Higgs potential is finely-tuned.

Two stops (LH/RH), one sbottom (LH) should be belowabout 500 - 700 GeV (e.g. 1110.6926 Papucci et al.)


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THE MSSM IS UNNATURALIn the MSSM, a 125 GeV Higgs mass requires heavystops / largeA-terms, but those directlyundermine thenaturalness argument for SUSY.

25

50

75

100

200200

500

500

1000

1000

-

4-

2 0 2 4

0

500

1000

1500

2000

2500

3000

Xtmt

mt

@GeVD

Higgs Mass vs. Fine Tuning

Suspect

FeynHiggs

Dmh

Tuning contours (Hall/Pinner/Ruderman

1112.2703) forlow-scale

mediation, .

Always at least a factor of100 tuning.

= 10 TeV


12/29

DICHOTOMY

Higgs at 125 GeV

Beyond MSSM,natural

Stop search;Higgs sector(rates, decays)

Models?(NMSSM, D-terms,

compositeness....)

MSSM, tunedwith heavyscalars

Gluinosearch

Top-downtheory

robustexperimentalconnection


13/29

NATURAL SUSY


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NATURAL SUSY

Have to complicate the MSSM in two ways:

1. Raise the Higgs mass to 125 GeV.Typicallynew tree-level interactions.

2. Explain lack of squark signals. Usually splitting1st/2nd gen from third. Example: U(2)3 flavor models (e.g.

1206.1327 by Barbieri, Buttazzo, Sala, Straub, less minimal flavor violation)

orhide the decays, so all squarks can be light: e.g. R-parityviolation (Barbieret al. review hep-ph/0406039, MFV RPV by Csaki,Grossman, Heidenreich)

, stealth supersymmetry(Fan, MR,

Ruderman )


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125 GEV, NATURALLYThe Higgs mass could be raised to 125 GeV by beyond-MSSM tree-level interactions (quartic terms).

W = SHuHd + f(S)

NMSSM / Fat Higgs /

lambdaSUSY

works best with low-

scale compositeness:higher-dim operatorsaround the corner?

SU(2) SU(2)

SU(2)

New D-terms:

Zbosons at afew TeV?

Look for more Higgses!


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DIRECT STOP LIMITS

2013 update: ATLAS and CMS are aggressively pursuingthe direct signatures of naturalness. No hints so far.


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TARGETING STOPS

NEXT STEPSProbe the scalar nature through spin correlations orrapidity differences (Z. Han, A. Katz, D. Krohn, MR, 1205.5808)

Allow forasymmetric decaystt!

t0

b+

(Graesser, Shelton 1212.4495)

(GeV)T2m0 20 40 60 80 100 120 140

)-1

#events/5GeV

(LHC75fb

-110

1

10

210

(our cuts)T2

dilep m

(GeV)Tm0 50 100 150 200 250

)-1

#events/10GeV

(LHC75fb

1

10

210

tt

(0)B~

t(220)R

t~

(0)0

h~t(220)

Rt~

(ATLAS cuts)T

l+jets m

Dileptonic mT2

(Kilic/Tweedie 1211.6106)

and more, for instance: Plehn et al 1102.0557 & 1205.2696; Bai et al

1203.4813; Alves et al. 1205.5805; Kaplan et al. 1205.5816, ....


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NATURALNESS AND

GLUINOSWe need the stop to be relatively light for naturalness of alight Higgs. But the stop is itselfa scalar field, and can get

quadratic corrections!

t t

t

g

g

tt tt t

g

Large corrections come from the gluino, which hence

should be light (below about 1.5 TeV). As a color octet,

the gluino has a large production cross section at the LHC.


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GLUINOS

gluino mass [GeV]500 600 700 800 900 1000 1100 1200 1300 1400 1500

LSPma

ss[GeV]

0

100

200

300

400

500

600

700

800

ObservedSUSYtheoryObserved -1

Expected

m(gluin

o)-m(LSP

)=2m(to

p)

Moriond 2013= 8 TeVs

CMS Preliminary

1

0ttg

~production,g

~-g

~

-1) 19.4 fbT

+HTESUS-12-024 0-lep (

-16) 19.4 fbjets

SUS-13-007 1-lep (n

-1SUS-12-017 2-lep (SS+b) 10.5 fb

-1SUS-12-026 (MultiLepton) 9.2 fb

gluino mass [GeV]500 600 700 800 900 1000 1100 1200 1300 1400 1500

LSPma

ss[GeV]

0

100

200

300

400

500

600

700

800

900

1000

Observed

SUSYtheoryObserved -1

Expected

kine

matic

ally

forbid

den

Moriond 2013= 8 TeVs

CMS Preliminary1

0bbg~production,g~-g~

-1) 19.4 fbT

+HT

ESUS-12-024 0-lep (

-1) 11.7 fbT

SUS-12-028 0-lep (

Gluino mass bounds are now above a TeV; e.g., 1.3 TeV ifgluino decays through stops.


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NATURAL SUSY: SUMMARY

Requires more complicated model-building: new Higgsinteractions, possible flavor problems / new flavor structures

those predict signals -- look for them!

Standard decay modes of stops, sbottoms, gluinos are beingruled out to uncomfortably high masses. Look for higgsinos!

RPV, stealth, other models could alter decays enough to evadebounds, for now...

Are we complicating the models so much that theyre less

appealing than tuning?


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UNNATURAL SUSY


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MSSM WITH LARGE A-TERMSThe least-tuned corner of the MSSM has largeAt.

This doesnt happen in General Gauge Mediation, but canhappen in extended models that add Yukawa mediation:new couplings of messengers to matter.

- - - -

- -- -

-

-

-

--

-

- - - - - - - -

-

- --

-

-- - - - - - - -

-

- -

-

-

-

- - - - - - - -

-

-- -

--

- - - - - - - --

- -

-

- - - - - - - --

- -

-

--- - - - - - - -

-

-- -

--

- - - - - - - --

--

-

--

I.8 I.9 I.10 I.11 I.12 I.13 I.14 I.15 I.9' I.13' II.1 II.2 II.3 II.7

100

250

500

700

1000

2000

3000

5000I.8 I.9 I.10 I.11 I.12 I.13 I.14 I.15 I.9' I.13' II.1 II.2 II.3 II.7

100

250

500

700

1000

2000

3000

5000

Model

MassHGeV

L

g

q

t

b

{

c 0

c +

Evans/Shih 1303.0228:

spectra of somemodels. Keep searchingfor stops and/orgluinos; slepton NLSPs.


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SEMI-SPLIT SUSY

Many models predict .mgaugino g2

162mscalar

Tuned EWSB. But: solves most of hierarchy problem(Planck down to ~100 TeV).

Gauge coupling unification works. SUSY dark matter also

possible. Helps flavor/CP problems.

Taken seriously early on by James Wells: hep-ph/0306127.Followed by Arkani-Hamed / Dimopoulos split SUSY,

others....


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HIGGS MASS IN SPLIT MODELS

105

106

107

108

109

100

110

120

130

140

MscHGeVL

Higgsmassmh

HGeVL

tan b = 1

tan b = 2

tan b = 4

tan b = 50

Arkani-Hamed et al 1212.6971; also see Acharya/Kane et al, Arvanitaki et al, Hall/Nomura


25/29

POTENTIAL SIGNALS

0

q

q

gq

c 105m mqPeV

4TeVmg

5.

The gluino remains the bestbet, possibly with a somewhat

displaced vertex.

Also, neutralino dark mattercould give signals in direct or

indirect detection experiments.

Arkani-Hamed et al 1212.6971


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WHY THE HIGH SCALE?

Why couldnt the whole spectrum have been lighter, bothsemi-split andnatural? (1TeV scalars, 1 GeV gauginos)

One possibility: moduli, scalar fields interacting withgravitational strength, tend to have mass anddecay width

3/2

m

3

M2Pl

Coherent moduli oscillations ruin cosmologyunless they decay early enough for BBN:

Treheat pMPl 10 MeV ) m 100 TeV

But 100 TeV soft scalar masses imply tuned EWSB!


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NONTHERMAL DARK MATTER

Considering moduli cosmology motivates pairing semi-

split SUSY with nonthermal dark mattergenerated through moduli decay.

see: Moroi/Randall hep-ph/9906527; J. Kaplan hep-ph/0601262; Gelmini/Gondolo hep-ph/0602230, Acharya/Kane/Kuflik 1006.3272, others....

For given , DM abundance is enhanced by a factor ofTfreezeout/TRH. Ideal for light wino DM, with largeannihilation rate.

hvi


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IN WINO VERITAS?Both thermal and nonthermal wino DM are in sometrouble from observations of the gamma-ray sky:

Wino thermal relic

HESS line HEinastoL Fermi line HNFWL

- Fermi dwarf 4 yrs- Hooper et. al. GC HNFWL- Hooper et. al. GC HEinastoL

100 1000500200 2000300 3000150 1500700

0.01

0.02

0.05

0.10

0.20

0.50

1.00

W

0

@GeVD

WW

0h2

WDM

h2

100 500 100010

-6

10-4

0.01

1

102

mW

0

@GeVD

TR

@GeVD

h = 1

BBN

Hard not to overproduce DM without even

heaviermoduli, RPV, or more complex cosmology.Preliminarywork in progress, J. Fan and MR.


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WHATS NEXT?

If SUSY is right, could well be beyond the MSSM. If SUSYis natural, it mustbe beyond MSSM.

Important to keep pushing stop and gluino searches, alsobroadening to RPV, etc, to really rule out naturalness.

Mildly split SUSY: scalars at ~100 to ~1000 TeV? Now sometension with dark matter / moduli constraints. Add RPV?

Keep looking for hard-to-find but theoretically motivatedoptions: displaced gluinos, light higgsino, pure higgsino DM....

Still hoping for more surprises!

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