Download Mass hierarchy and physics beyond the Standard Theory

Mass hierarchy and physics beyond the Standard Theory
I. Antoniadis
Why mH = 126 GeV?
IFT UAM/CSIC, Madrid, 25-27 September 2013
Low energy SUSY and 126 GeV Higgs
Live with the hierarchy
Low scale strings and extra dimensions
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Entrance of the Higgs Boson in the Particle Data Group 2013
particle
listing
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Entrance of the Higgs Boson in the Particle Data Group 2013
summary tables
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Couplings of the new boson vs SM
exclusion : spin 2 and pseudoscalar at >
∼ 95% CL
Agreement with Standard Model expectation at ∼ 2 σ
I. Antoniadis (CERN)
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Remarks on the value of the Higgs mass ∼ 126 GeV
consistent with expectation from precision tests of the SM
favors perturbative physics
2 /v 2 ≃ 1/8
quartic coupling λ = mH
1st elementary scalar in nature signaling perhaps more to come
triumph of QFT and renormalized perturbation theory!
Standard Theory has been tested with radiative corrections
Window to new physics ?
very important to measure precisely its properties and couplings
several new and old questions wait for answers
Dark matter, neutrino masses, baryon asymmetry, flavor physics,
axions, electroweak scale hierarchy, early cosmology, . . .
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6
5
incertitude théorique
∆α
(5)
∆αhad
= 0.02761±0.00036
∆χ2
4
3
95% CL
2
0
région exclue
20
100
260
1
400
mH [GeV]
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Beyond the Standard Theory of Particle Physics:
driven by the mass hierarchy problem
Standard picture: low energy supersymmetry
Natural framework: Heterotic string (or high-scale M/F) theory
Advantages:
natural elementary scalars
gauge coupling unification
LSP: natural dark matter candidate
radiative EWSB
Problems:
too many parameters: soft breaking terms
MSSM : already a % - %0 fine-tuning
I. Antoniadis (CERN)
‘little’ hierarchy problem
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What to do?
Physics is an experimental science
We must fully explore the multi TeV energy range
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We must fully explore the 10-100 TeV energy range
ILC project
The future of LHC
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VHE-LHC: location and size
A circumference of 100 km is being considered for cost-benefit reasons
20T magnet in 80 km / 16T magnet in 100 km → 100 TeV
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126 GeV Higgs and SUSY
compatible with supersymmetry (even with MSSM)
although it appears fine-tuned in its minimal version
but early to draw a general conclusion before LHC13/14
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Fine-tuning in MSSM
Upper bound on the lightest scalar mass:
"
4
mt̃2
3
A2t
m
t
2
2
mh2 <
∼ mZ cos 2β + (4π)2 v 2 ln m2 + m2
t
t̃
A2t
1−
12mt̃2
!#
2
<
∼ (130GeV )
mh ≃ 126 GeV => mt̃ ≃ 3 TeV or At ≃ 3mt̃ ≃ 1.5 TeV
=> % to a few %0 fine-tuning
minimum of the potential: mZ2 = 2
RG evolution: m22 = m22 (MGUT ) −
m11 − m22 tan2β
tan2 β − 1
∼ −2m22 + · · ·
3λ2t 2 MGUT
+ ···
m ln
4π 2 t̃
mt̃
[27]
∼ m22 (MGUT ) − O(1)mt̃2 + · · ·
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Reduce the fine-tuning
minimize radiative corrections
MGUT → Λ : low messenger scale (gauge mediation)
δmt̃2 =
Λ
8αs 2
M ln
+ ···
3π 3 M3
increase the tree-level upper bound => extend the MSSM
see Graham’s talk
extra fields beyond LHC reach → effective field theory approach
···
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MSSM with dim-5 and 6 operators
I.A.-Dudas-Ghilencea-Tziveloglou ’08, ’09, ’10
parametrize new physics above MSSM by higher-dim effective operators
relevant super potential operators of dimension-5:
Z
1
L(5) =
d 2 θ (η1 + η2 S) (H1 H2 )2
M
η1 : generated for instance by a singlet
W = λσH1 H2 +Mσ 2
→
Weff =
λ2
(H1 H2 )2
M
Strumia ’99 ; Brignole-Casas-Espinosa-Navarro ’03
Dine-Seiberg-Thomas ’07
η2 : corresponding soft breaking term
I. Antoniadis (CERN)
spurion S ≡ mS θ 2
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Physical consequences of MSSM5 : Scalar potential
2
g22 + gY2
|h1 |2 − |h2 |2
8
1
η2 (h1 h2 )2 + h.c.
+ |h1 |2 + |h2 |2 (η1 h1 h2 + h.c.) +
2
V = m12 |h1 |2 + m22 |h2 |2 + Bµ(h1 h2 + h.c.) +
+ η12 |h1 h2 |2 (|h1 |2 + |h2 |2 )
η1,2 => quartic terms along the D-flat direction |h1 | = |h2 |
tree-level mass can increase significantly
bigger parameter space for LSP being dark matter
Bernal-Blum-Nir-Losada ’09
last term ∼ η12 : guarantees stability of the potential
but requires addition of dim-6 operators
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MSSM Higss with dim-6 operators
dim-6 operators can have an independent scale from dim-5
Classification of all dim-6 contributing to the scalar potential
(without SUSY)
/
=>
large tan β expansion: δ6 mh2 = f v 2 + · · ·
ր
constant receiving contributions from several operators
f ∼ f0 × µ2 /M 2 , mS2 /M 2 , µmS /M 2 , v 2 /M 2
mS = 1 TeV, M = 10 TeV, f0 ∼ 1 − 2.5 for each operator
=> mh ≃ 103 − 119 GeV
=> MSSM with dim-5 and dim-6 operators:
possible resolution of the MSSM fine-tuning problem
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Can the SM be valid at high energies?
Degrassi-Di Vita-Elias Miró-Espinosa-Giudice-Isidori-Strumia ’12
Instability of the SM Higgs potential => metastability of the EW vacuum
see Misha’s talk
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SUSY : λ = 0 => tan β = 1
HSM = sin β Hu − cos β Hd∗
λ = 18 (g22 + g ′2 ) cos2 2β
λ = 0 at a scale ≥ 1010 GeV => mH = 126 ± 3 GeV
Ibanez-Valenzuela ’13
#$
(#
)
*
+
%#&
'
!"
,#& '
,#& '
,#&
'
,#&
e.g. for universal
I. Antoniadis (CERN)
√
2m = M = MSS , A = −3/2M
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If the weak scale is tuned => split supersymmetry is a possibility
Arkani Hamed-Dimopoulos ’04, Giudice-Romaninio ’04
natural splitting: gauginos, higgsinos carry R-symmetry, scalars do not
main good properties of SUSY are maintained
gauge coupling unification and dark matter candidate
also no dangerous FCNC, CP violation, . . .
experimentally allowed Higgs mass => ‘mini’ split
[27]
mS ∼ few - thousands TeV
gauginos: a loop factor lighter than scalars (∼ m3/2 )
natural string framework: intersecting (or magnetized) branes
IA-Dimopoulos ’04
D-brane stacks are supersymmetric with massless gauginos
intersections have chiral fermions with broken SUSY & massive scalars
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An extra U(1) can also cure the instability problem
Anchordoqui-IA-Goldberg-Huang-Lüst-Taylor-Vlcek ’12
usually associated to known global symmetries of the SM: B, L, . . .
B anomalous and superheavy
B − L massless at the string scale (no associated 6d anomaly)
but broken at TeV by a scalar VEV with the quantum numbers of NR
L-violation from higher-dim operators suppressed by the string scale
U(3) unification, Y combination => 2 parameters: 1 coupling + mZ ′′
perturbativity => 0.5 <
∼ gU(1)R <
∼1
interesting LHC phenomenology and cosmology
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Alternative answer: Low UV cutoff Λ ∼ TeV
- low scale gravity => extra dimensions: large flat or warped
- low string scale => low scale gravity, ultra weak string coupling
n = 1032 l n (R ∼ .1 − 10−13 mm for n = 2 − 6)
Ms ∼ 1 TeV => volume R⊥
⊥
s
- spectacular model independent predictions
- radical change of high energy physics at the TeV scale
Moreover no little hierarchy problem:
radiative electroweak symmetry breaking with no logs
[18]
2 = a loop factor × Λ2
Λ ∼ a few TeV and mH
But unification has to be probably dropped
New Dark Matter candidates e.g. in the extra dims
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Origin of EW symmetry breaking?
possible answer: radiative breaking
I.A.-Benakli-Quiros ’00
V = µ2 H † H + λ(H † H)2
µ2 = 0 at tree but becomes < 0 at one loop
non-susy vacuum
simplest case: one scalar doublet from the same brane
=> tree-level V same as susy: λ = 81 (g22 + g ′2 )
D-terms
µ2 = −g 2 ε2 Ms2 ← effective UV cutoff
e −πl
ց
ր
Z
1 X 2 −2πn2 R 2 l
R 3 ∞ 3/2 θ24
2
ε (R) =
il +
dll
n e
2π 2 0
16l 4 η 12
2
n
ր
ց
IR
1
UV
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0.20
0.15
ε
0.10
0.05
0.00
0.25
1.00
1.75
2.50
3.25
4.00
4.75
R
R → 0 : ε(R) ≃ 0.14
large transverse dim R⊥ = ls2 /R → ∞
R → ∞ : ε(R)Ms ∼ ε∞ /R
ε∞ ≃ 0.008
UV cutoff: Ms → 1/R
Higgs scalar = component of a higher dimensional gauge field
=> ε∞ calculable in the effective field theory
λ = g 2 /4 ∼ 1/8
=>
MH ≃ v /2 = 125 GeV
Ms or 1/R ∼ a few or several TeV
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Accelerator signatures: 4 different scales
Gravitational radiation in the bulk => missing energy
present LHC bounds: M∗ >
∼ 3 − 5 TeV
Massive string vibrations => e.g. resonances in dijet distribution
Mj2 = M02 + Ms2 j
;
maximal spin : j + 1
higher spin excitations of quarks and gluons with strong interactions
present LHC limits: Ms >
∼ 5 TeV
Large TeV dimensions => KK resonances of SM gauge bosons I.A. ’90
Mk2 = M02 + k 2 /R 2 ; k = ±1, ±2, . . .
experimental limits: R −1 >
∼ 0.5 − 4 TeV (UED - localized fermions)
extra U(1)’s and anomaly induced terms
masses suppressed by a loop factor from Ms
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[32]
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Extra U(1)’s and anomaly induced terms
masses suppressed by a loop factor
usually associated to known global symmetries of the SM
(anomalous or not) such as (combinations of)
Baryon and Lepton number, or PQ symmetry
Two kinds of massive U(1)’s:
- 4d anomalous U(1)’s:
I.A.-Kiritsis-Rizos ’02
MA ≃ gA Ms
- 4d non-anomalous U(1)’s: (but masses related to 6d anomalies)
MNA ≃ gA Ms V2 ← (6d→4d) internal space
=> MNA ≥ MA
or massless in the absence of such anomalies
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Standard Model on D-branes : SM++
1-Right
2-Left
gluon
U(3)
3-Baryonic
QL
UR , D R
W
#-Leptonic
U(1) L
LL
Sp(1) ≡ SU(2)
ER ! "
U(1) R
U(1)3 ⇒ hypercharge + B, L
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TeV string scale
Anchordoqui-IA-Goldberg-Huang-Lüst-Taylor ’11
B and L become massive due to anomalies
Green-Schwarz terms
the global symmetries remain in perturbation
- Baryon number => proton stability
- Lepton number => protect small neutrino masses
no Lepton number =>
B, L => extra Z ′ s
1
Ms LLHH
→ Majorana mass:
hHi2
Ms LL
տ
∼ GeV
with possible leptophobic couplings leading to CDF-type Wjj events
Z ′ ≃ B lighter than 4d anomaly free Z ′′ ≃ B − L
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Conclusions
Confirmation of the EWSB scalar at the LHC:
important milestone of the LHC research program
Precise measurement of its couplings is of primary importance
Hint on the origin of mass hierarchy and of BSM physics
natural or unnatural SUSY?
low string scale in some realization?
something new and unexpected?
all options are still open
LHC enters a new era with possible new discoveries
Future plans to explore the 10-100 TeV energy frontier
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The LHC timeline
LS1 Machine Consolidation
!"#$%&'()*'$
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LS2 Machine upgrades for high Luminosity
7F.EH.I% >$4?#$4%()*%'&$%
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• 
Collimation
• 
Cryogenics
• 
Injector upgrade for high intensity (lower emittance)
• 
Phase I for ATLAS : Pixel upgrade, FTK, and new small wheel
LS3 Machine upgrades for high Luminosity
• 
Upgrade interaction region
• 
Crab cavities?
• 
Phase II: full replacement of tracker, new trigger scheme (add L0), readout
electronics.
Europe’s top priority should be the exploitation
of the full potential of the LHC, including the
high-luminosity upgrade of the machine and
detectors with a view to collecting ten times
more data than in the initial design, by around
2030.
I. Antoniadis (CERN)
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