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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)
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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!
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125 GEV HIGGS AND SUSY
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125 GEV HIGGS AND SUSY
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
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125 GEV HIGGS AND SUSY
m2h = m2
Zc2
2
+3m4t42v2
log
M2
S
m2t
+X2tM2
S
1
X2t12M2
S
Haber, Hempfling 91
more: Haber, Hempfling, Hoang, Ellis, Ridolfi, Zwirner, Casas, Espinosa, Quiros, Riotto,Carena, Wagner, Degrassi, Heinemeyer, Hollik, Slavich, Weiglein
Tree-level bound: 90 GeV
Very interesting! Light enough that SUSY stillseems sane, but heavy enough that manymodels dont.
MSSM:h h
t
+h h
t
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125 GEV HIGGS AND SUSY
m2h = m2
Zc2
2
+3m4t42v2
log
M2
S
m2t
+X2tM2
S
1
X2t12M2
S
Haber, Hempfling 91
more: Haber, Hempfling, Hoang, Ellis, Ridolfi, Zwirner, Casas, Espinosa, Quiros, Riotto,Carena, Wagner, Degrassi, Heinemeyer, Hollik, Slavich, Weiglein
Very interesting! Light enough that SUSY stillseems sane, but heavy enough that manymodels dont.
MSSM:h h
t
+h h
t
Logarithmic growth with stop mass
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125 GEV HIGGS AND SUSY
m2h = m2
Zc2
2
+3m4t42v2
log
M2
S
m2t
+X2tM2
S
1
X2t12M2
S
Haber, Hempfling 91
more: Haber, Hempfling, Hoang, Ellis, Ridolfi, Zwirner, Casas, Espinosa, Quiros, Riotto,Carena, Wagner, Degrassi, Heinemeyer, Hollik, Slavich, Weiglein
Very interesting! Light enough that SUSY stillseems sane, but heavy enough that manymodels dont.
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
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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
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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
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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!