New Models
Savas Dimopoulos
with
Nima Arkani-Hamed
Small numbers and hierarchy
problems
1018 GeV
MPL
103 GeV
MW
10−12 GeV
1
4
Gauge Hierarchy
Problem
Cosmological Constant
Problem
ρvac
Program of the last 30 years:
Seek “Natural” explanations of these numbers
Outline
•M
ρ
•
M
•
weak
vacuum
in theories with few vacua
in theories with many vacua
in theories with many vacua:
Split Supersymmetry
weak
Approaches to the gauge hierarchy problem
Stages:
•
•
•
Philosophy (1974)
[Wilson]
Technicolor (1978)
[Susskind, Weinberg]
Supersymmetric Standard
Model (1981)
[S.D., Georgi]
•
Low Scale Gravity
(1998)
[Antoniadis, Arkani-Hamed, S.D.,
Dvali]
•
•
Warped Gravity (1999)
[Randall, Sundrum]
Little Higgs (2001)
[Arkani-Hamed, Cohen, Georgi]
Supersymmetric Standard Model
Introduces “Superpartners” at the weak scale
Successes
◦ Uni f ication
◦ Dark Matter
Shortcomings
◦ Higgs ?
◦ Sparticles ?
◦ FCNC ; CP
◦ Proton Decay
Fermions
• Hierarchy Problem
◦ Gravitino − Moduli Problem
Scalars
• Cosmological Constant
ρ
Strategy for the last 30 years
m
weak
↑
Focus on this
↑ vacuum
Ignore this
This could be flawed
In theories with few vacua
ρvacuum
Getting
ρvacuum ∼ (10
−15
MW )
4
Looks like divine intervention!
Since any bigger value would rip apart galaxies
However...
(Weinberg 1987)
In theories with many vacua
Therefore, if there are enough vacua with different ρvacuum ,
the “structure” principle can explain why we live in a
universe with small, but nonzero, ρvacuum
This reasoning correctly predicted a small ρ
vacuum
and has recently gained momentum because string theory
may well have a vast “landscape” of metastable vacua
100s
10
Bousso, Polchinski; Kachru et.al.; Douglas et.al.; Susskind
Similarly, if there are enough vacua with different M Weak
the “atomic” principle can explain the value of M Weak
Donoghue et.al. 1998
New approach
The mechanism solving the cosmological constant problem,
may also solve the hierarchy problem
Can we preserve the successes of the low energy SUSY?
Split Supersymmetry
1016 TeV
MPl.
Scalars
Msusy
Fermions
Mweak
(Squarks, sleptons, ...)
(Higgsinos, gauginos)
+SM Higgs
?{
109 TeV
10 TeV
1 TeV
Preserves gauge unification and DM candidate!
Particles and Couplings
! W
! g̃
B
H
Higgs
Gauginos
!u H
!d
H
Higgsinos
"d
! 2 + m2 W
" 2 + m3 g̃ 2 + µH
"u H
m1 B
4
2
2
λ|H| − m |H|
!u W
! + κd H † H
!d W
!
κu H H
!u B
" + κ!d H † H
!d B
"
κ!u H H
"
1! 2
!2
2= g cos β
κ
κ
=
g
sin
β
d 2β
Gaugino
Higgs Quartic
Yukawas λ =u g + g
cos
8
5 Couplings from 1 parameter!
Unification in MSSM
α1−1
α2−1
α3−1
E (GeV)
Gauge Coupling Unification
Squarks and Sleptons don’t alter unification
MSSM
Split Susy
Msusy
α1−1
50
40
α2−1 30
20
α3−1
6
8
10
12
E(GeV)
14
16
Fig. 3. Running couplings in our model at one-loop, with the scalars at 109 GeV.
The heavy Higgs of Split SUSY
!
tan β → ∞
!
170
Higgs Mass !GeV#
160
tan β = 1
150
140
130
120
110
2
4
6
8
10
12
14
Log10 !Ms "GeV# A. Arvanitaki, et al hep-ph/0406034
Long-Lived Light Gluinos
Must decay through squarks
j
q̄
g̃
q̃
q
j
/T
B̃ E
τg̃ ! 2 sec.
!
350 GeV
mg̃
"5 !
MSusy
106 TeV
"4
Gluino Phenomenology
• LHC: Gluino Factory, ~1 gluino/sec! (350
GeV)
• Bound States: g̃g, g̃qq̄, g̃qqq (R-Hadrons)
• Charged and intermittent tracks
• Displaced gluinos
• Stopped, late-decaying gluinos!
Post-LHC
• A long lived strongly interacting particle
• A few ‘electroweakinos’
• Doesn’t match SUSY traditional models’
signatures
• Doesn’t look natural...
• What is it?
Yukawa Couplings’ Unification
−→
! !
κ
κ
λ u d κu κd
30%
λ
0.0
κ
−30%
% Change from Susy value
Msusy tan β
κ!
0
10
3
10
TeV
6
10
A. Arvanitaki, et al hep-ph/0406034
ILC Measurements
•
Kilian et.al. 2004
8 parameters (M1, M2, µ, κu, κd , κ!u, κ!d , λ)
+ CP violating phases
• Charged masses measured through threshold
scans
• Mass differences through electroweak
decays
• all couplings measurable in multiple ways
SUSY: clean environment
• Split
(free of scalar pollution)
Gauginos
and
Higgsinos
Long-lived Gluinos
Split SUSY
in colliders
Yukawa
Unification
Window to the
Landscape?