Neutrinos and 125 GeV Higgs what are they telling us
about the Universe?
Mikhail Shaposhnikov
Moriond, March 29 2017 – p. 1
The LHC has discovered something
quite unexpected : the Higgs boson and
nothing else, confirming the Standard
Model.
Moriond, March 29 2017 – p. 2
The LHC has discovered something
quite unexpected : the Higgs boson and
nothing else, confirming the Standard
Model.
No low energy SUSY, no large extra dimensions, no new strong
interactions.
Moriond, March 29 2017 – p. 2
The LHC has discovered something
quite unexpected : the Higgs boson and
nothing else, confirming the Standard
Model.
No low energy SUSY, no large extra dimensions, no new strong
interactions.
For 125 GeV Higgs mass the Standard Model is a self-consistent
weakly coupled effective field theory for all energies up to the quantum
gravity scale MP ∼ 1019 GeV
Moriond, March 29 2017 – p. 2
The LHC results must be reconciled with experimental evidence for
new physics beyond the Standard Model:
Observations of neutrino oscillations (in the SM neutrinos are
massless and do not oscillate)
Evidence for Dark Matter (SM does not have particle physics
candidate for DM).
No antimatter in the Universe in amounts comparable with matter
(baryon asymmetry of the Universe is too small in the SM)
Cosmological inflation is absent in canonical variant of the SM
Accelerated expansion of the Universe (?) - though can be
“explained” by a cosmological constant.
Moriond, March 29 2017 – p. 3
Marginal evidence (less than 2σ) for the SM vacuum metastability
given uncertainties in relation between Monte-Carlo top mass and
the top quark Yukawa coupling
V
V
V
M
stability
Fermi
Planck
crit
metastability
φ
φ
Fermi
Planck
φ
Fermi
Planck
Moriond, March 29 2017 – p. 4
Buttazzo et al, ’13, ’14:
Bednyakov et al, ’15:
vacuum is unstable at 2.8σ
vacuum is unstable at 1.3σ
Bezrukov, MS
updated
metastable
region
Main uncertainty: top Yukawa coupling, relation between the MC mass and the top
Yukawa coupling allows for ±1 GeV in Mtop . Alekhin et al, Frixione et al.
Moriond, March 29 2017 – p. 5
Vacuum lifetime
129
128
mh , GeV
127
126
125
124
123
10320 tU
1080 tU
1020 tU
122
170 171 172 173 174 175 176 177
mt , GeV
Moriond, March 29 2017 – p. 6
Where is new physics?
Moriond, March 29 2017 – p. 7
Energy scale of new physics:
Neutrino masses and oscillations: the masses of right-handed
see-saw neutrinos can vary from O(1) eV to O(1015 ) GeV
Dark matter, absent in the SM: the masses of DM particles can be
as small as O(10−22 ) eV (super-light scalar fields) or as large as
O(1020 ) GeV (wimpzillas, Q-balls).
Baryogenesis, absent in the SM: the masses of new particles,
responsible for baryogenesis (e.g. right-handed neutrinos), can
be as small as O(10) MeV or as large as O(1015 ) GeV
Higgs mass hierarchy : models related to SUSY, composite Higgs,
large extra dimensions require the presence of new physics right
above the Fermi scale , whereas the models based on scale
invariance (quantum or classical) may require the absence of new
physics between the Fermi and Planck scales
Moriond, March 29 2017 – p. 8
The missing piece of the SM
!"#
((
Right
Right
Right
Left
Right
Left
Right
Left
' !"
Left
Left
Left
Left
Left
Right
Left
Left
Right
Left
Left
Right
(((
Right
(
)*+
Moriond, March 29 2017 – p. 9
The missing piece of the SM
Right
Left
Left
Right
Left
Left
' !"
Right
Right
Left
Left
)*+
Right
Left
Right
Left
Right
Left
Left
Right
Left
Left
Right
' !"
Right
Right
Left
(((
Right
Left
Right
Left
Right
Left
Left
Left
Left
Left
Right
Left
Left
((
(
Right
Left
Left
Right
(((
((
(
!"#
Right
!"#
)*+
Moriond, March 29 2017 – p. 9
New mass scale and Yukawas
Y 2 = T race[F † F ]
✟✠✟✡ ☛☞
✌ ✍☛☞
✌✟
■
✎☛☞
✁☎
●❆❇❉❃❏ ❑❉❅▲❍❈❃❏
✿
❁❀
❂
✁✁✁
✁✆
✼
✽
✸
✾
✤✥ ✦✧✧★✦✩✪
✁- ✝
✺
✻
✺
✁- ✞
✷
✸
✹
✁- ✂✄
✁- ✂☎
❃❄❅❆❇❈❃❉ ❊❋●●❄● ❋❇❄ ❆❉❉ ●❊❋❍❍
✁- ✂✄
✓✔✕✖
✁- ☎
✁✆
✜ ✢✣✢
✁✝
✁✂✂
✏✑✒
✎✗✍
✁✂☎
✘☛☛✙✘✚✛
✫✬✭✮✯✬✰✬ ✱✬✲✲✳ ✴✵✶
Moriond, March 29 2017 – p. 10
New physics below the Fermi scale
!"#
((
Left
Right
Left
Right
Left
Right
Right
Left
Left
Left
Left
The νMSM = particles of the SM
' !"
Right
Left
Right
Left
Left
Right
Left
Left
Right
(((
Right
(
+ graviton +
3 Majorana leptons
)*+
Lagrangian:
c
µ
LνMSM = LSM +LG + N̄I iγ ∂µ NI − hαI L̄α NI ϕ̃ − MI N̄I NI + h.c.
Gravity part
LG = −
MP2
†
+ 2ξh ϕ ϕ
R
2
,
Moriond, March 29 2017 – p. 11
Roles of the Higgs boson:
Provide inflation
Give masses to fermions and vector bosons of the SM
Provide CP-violating Yukawa couplings in the leptonic sector
necessary for baryogenesis
Provide Yukawa couplings in the leptonic sector necessary for DM
production
Roles of the HNLs
N1 with mass in keV region: dark matter
N2 , N3 with mass in 100 MeV – GeV region: “give” masses to
neutrinos and produce baryon asymmetry of the Universe
Moriond, March 29 2017 – p. 12
Cosmology of a minimal model
Moriond, March 29 2017 – p. 13
Inflation: Higgs boson
Potential in Einstein frame for non-minimally coupled Higgs, ξh Rh2 .
2
2
Higgs field determines the strength of gravity, G−1
+
ξ
h
!
=
M
h
N
P
U(χ)
λM4/ξ2/4
Standard Model
λ v4/4
4 2
λM /ξ /16
0
0
0
v
0
χ
χ - canonically normalised scalar field in Einstein frame.
Moriond, March 29 2017 – p. 14
√P , slow roll of the Higgs
Stage 1: Higgs inflation, h > M
ξ
field
U(χ)
λM4/ξ2/4
inflation
4 2
λM /ξ /16
0
0
χend
χCOBE χ
Makes the Universe flat, homogeneous and isotropic
Produces fluctuations leading to structure formation: clusters of
galaxies, etc
Moriond, March 29 2017 – p. 15
CMB parameters - spectrum and tensor
modes, ξ & 1000
ns = 0.97, r = 0.003
Moriond, March 29 2017 – p. 16
Stage 2: Big Bang,
MP
ξ
<h<
M
√P
ξ
, Higgs field oscillations
U(χ)
Reheating
λM4/ξ2/4
λM4/ξ2/16
0
0
χend
χCOBE χ
All particles of the Standard Model are produced
Coherent Higgs field disappears
The Universe is heated up to T ∝ MP /ξ ∼ 1014 GeV
Moriond, March 29 2017 – p. 17
Dark Matter and baryon
asymmetry
Moriond, March 29 2017 – p. 18
All comes due to the HNL interactions with the Higgs boson via
Yukawa interactions - exactly in the same way other fermions do:
N
H
FαI L̄α NI H̃
ν
These interactions lead to
active neutrino masses due to GeV scale see-saw
to dark matter production at T ∼ 100 MeV: Dodelson, Widrow;
Shi, Fuller; + many recent works
creation of matter-antimatter asymmetry at temperatures
T ∼ 100 GeV: Akhmedov, Rubakov, Smirnov; Asaka, MS; +
many recent works
Moriond, March 29 2017 – p. 19
DM candidate: the lightest Majorana ν, N1
Yukawa couplings are small
→ sterile N can be very stable.
For one flavour:
26
τN1 = 5×10
N
sec
ν
1keV
M1
5
−8
10
Θ2
Z
ν
ν
Θ=
mD
MI
Main decay mode: N → 3ν.
Moriond, March 29 2017 – p. 20
!
Dark Matter candidate: N1
DM particle is not stable. Main
decay mode N1 → 3ν is not
observable.
Subdominant radiative decay
channel: N → νγ.
Ns
Photon energy:
Eγ =
ν
e±
ν
W∓
M
W∓
γ
2
Radiative decay width:
Γrad =
9 αEM G2F
256 · 4π 4
sin2 (2θ) Ms5
Moriond, March 29 2017 – p. 21
Constraints on DM sterile neutrino N1
Stability. N1 must have a lifetime larger than that of the Universe
Production. N1 are created in the early Universe in reactions
ll̄ → νN1 , q q̄ → νN1 etc. We should get correct DM
abundance
Structure formation. If N1 is too light it may have considerable
free streaming length and erase fluctuations on small scales. This
can be checked by the study of Lyman-α forest spectra of distant
quasars and structure of dwarf galaxies
X-rays. N1 decays radiatively, N1 → γν, producing a narrow line
which can be detected by X-ray telescopes (such as Chandra or
XMM-Newton).
Moriond, March 29 2017 – p. 22
Too much Dark Matter
-7
10
Non-
reso
10-8
10-9
10-10
-11
10
10-12
-13
10
nant
prod
Excluded by non-observation
of dark matter decay line
ucti
Phase-space density
constraints
Interaction strength [Sin2(2θ)]
10-6
on
Lyman-α bound
for NRP sterile neutrino
L
6 =1
2
L6 =
25
L6 =7
0
BBN
limi
t: L BBN
6
10-14
L6max=
700
= 25
00
Not enough Dark Matter
1
5
10
DM mass [keV]
50
Detection of An Unidentified Emission Line in the Stacked X-ray
spectrum of Galaxy Clusters. E. Bulbul, M. Markevitch, A. Foster, R. K.
Smith, M. Loewenstein, S. W. Randall. e-Print: arXiv:1402.2301
An unidentified line in X-ray spectra of the Andromeda galaxy and
Perseus galaxy cluster. A. Boyarsky , O. Ruchayskiy, D. Iakubovskyi, J.
Franse. e-Print: arXiv:1402.4119
Moriond, March 29 2017 – p. 23
HNL (N1 ) dark matter searches in X-rays, future after Astro-H
failure
New Hitomi, 2020?
Micro-calorimeter on sounding rocket (2017): instrument with
large field-of-view and very high spectral resolution
Large ESA X-ray mission (2028) – Athena + , X-ray
spectrometer (X-IFU) with unprecedented spectral resolution
Moriond, March 29 2017 – p. 24
Baryon asymmetry
Sakharov conditions:
Baryon number violation - OK due co complex vacuum structure
in the SM and chiral anomaly
CP-violation - OK due to new complex phases in Yukawa
couplings
Deviations from thermal equilibrium - OK as HNL are out of
thermal equilibrium for T > O(100) GeV
Moriond, March 29 2017 – p. 25
Baryon asymmetry
Akhmedov, Rubakov, Smirnov; Asaka, MS
Idea - N2,3 HNL oscillations as a source of baryon asymmetry.
Qualitatively:
HNL are created in the early universe and oscillate in a coherent
way with CP-breaking.
Lepton number from HNL can go to active neutrinos.
The lepton number of active left-handed neutrinos is transferred to
baryons due to equilibrium sphaleron processes.
Moriond, March 29 2017 – p. 26
Constraints on BAU HNL N2,3
Baryon asymmetry generation: CP-violation in neutrino sector+singlet
fermion oscillations+sphalerons
BAU generation requires out of equilibrium: mixing angle of N2,3
to active neutrinos cannot be too large
Neutrino masses. Mixing angle of N2,3 to active neutrinos cannot
be too small
BBN. Decays of N2,3 must not spoil Big Bang Nucleosynthesis
Experiment. N2,3 have not been seen
Moriond, March 29 2017 – p. 27
NuTeV
CHARM
10-6
PS
1
BAU
N
U2
BB
U2
PS
19
19
10-8
CHARM
10-6
NuTeV
BB
10-8
BAU
BAU
10-10
BAU
1
N
10-10
Seesaw
Seesaw
10-12
0.2
0.5
1.0
2.0
5.0
M @GeVD
10.0
10-12
0.2
0.5
1.0
2.0
5.0
10.0
M @GeVD
Constraints on U 2 coming from the baryon asymmetry of the Universe,
from the see-saw formula, from the big bang nucleosynthesis and
experimental searches. Left panel - normal hierarchy, right panel inverted hierarchy (Canetti, Drewes, Frossard, MS). Other studies:
Drewes et al., Hernandez et al
Moriond, March 29 2017 – p. 28
Experimental search for HNL
Production
via intermediate (hadronic) state
p + target → mesons + ..., and then hadron→ N + ....
via Z-boson decays: e+ e− → Z → νN
Detection
Subsequent decay of N to SM particles
♠
❉s
♠
♥
◆
❍
✉
◆✷✁✂
♥✂
✷ ✁
❍
♣
✉
♠
❉
♠
♥
✉
♣
❍
◆✷✁✂
◆
✷ ✁
♥✂
❡
❍
✉
♥✄
Moriond, March 29 2017 – p. 29
Survey of constraints
0
10
-1
10
NA3
-2
10
CHARM II
-3
10
L3
|Vµ4|
2
-4
10
DELPHI
-5
10
FMMF
-6
10
BEBC
-7
10
-8
10
K --> µ ν
NuTeV
PS 191
-9
10
0.1
1
10
100
m4 (GeV)
Atre et al.
Moriond, March 29 2017 – p. 30
How to improve the bounds or to
discover light very weakly
interacting HNL’s?
Moriond, March 29 2017 – p. 31
Dedicated experiments
Common features of all relatively light feebly interacting particles :
Can be produced in decays of different mesons (π, K, charm, beauty)
Can decay to SM particles (l+ l− , γγ, lπ, etc)
Can be long lived
Requirements to experiment:
Produce as many mesons as you can
Study their decays for a missing energy signal: charm or B-factories, NA62, BNL
E949
Search for decays of hidden sector particles - fixed target experiments
Have as many pot as you can, with the energy enough to produce charmed
(or beauty) mesons
Put the detector as close to the target as possible, in order to catch all hidden
particles from meson decays (to evade 1/R2 dilution of the flux)
Have the detector as large as possible to increase the probability of hidden
particle decay inside the detector
Have the detector as empty as possible to decrease neutrino and other
backgrounds
Moriond, March 29 2017 – p. 32
Proposal to Search for Heavy Neutral
Leptons at the SPS arXiv:1310.1762
W. Bonivento, A. Boyarsky, H. Dijkstra, U. Egede, M. Ferro-Luzzi, B.
Goddard, A. Golutvin, D. Gorbunov, R. Jacobsson, J. Panman, M.
Patel, O. Ruchayskiy, T. Ruf, N. Serra, M. Shaposhnikov, D. Treille
⇓
General beam dump facility: Search for
Hidden Particles
Moriond, March 29 2017 – p. 33
Hidden sector: very weakly interacting relatively light particles: HNL,
dark photon, scalars, ALPS, etc
Moriond, March 29 2017 – p. 34
SHiP is currently a collaboration of 46 institutes from 15 countries
web-site: http://ship.web.cern.ch/ship/
Moriond, March 29 2017 – p. 35
FCC-ee Z-factory, LHC
Processes: Z → N ν,
jets),
N → lq q̄ (lepton + meson, lepton + 2 quark
2
BR(Z → νN ) ≃ BR(Z → νν)U ,
ΓN
5
G2
2
FM
≃
U
A
192π 3
Coefficient A counts the number of open channels, A ∼ 10 for M > 10 GeV
Detector of size L:
“short lived” N: decay length < L =⇒ constraint on U 2 may go
down to U 2 < 10−10 as the sensitivity will grow as the number of
Z-decays! This works for M & 20 GeV.
“long lived” N: decay length exceeds the size of the detector =⇒
constraint on U 2 may go down to U 2 < 4 × 10−8 as the
sensitivity will grow as the square root of the number of Z-decays.
This works for lighter HNL.
Moriond, March 29 2017 – p. 36
SHiP and FCC-ee sensitivity
Normal hierarchy
Normal hierarchy
10-6
10-6
NuTeV
NuTeV
10-7
PS191
BAU
SHiP
10-9
10-10
FCC-ee
BBN
PS191
BAU
10-8
|U|2
|U|2
10-8
NuTeV
10-7
SHiP
10-9
10-10
FCC-ee
BBN
PS191
BAU
10-8
|U|2
10-7
Normal hierarchy
10-6
SHiP
10-9
BBN
10-10
FCC-ee
10-11
10-11
Seesaw
1
Seesaw
10
1
HNL mass (GeV)
10
NuTeV
CHARM
Inverted hierarchy
10-6
CHARM
10
PS191
-7
10
PS191
10
FCC-ee
10-8
SHiP
10-9
10-10
|U|2
|U|2
10
|U|2
BAU
-8
BBN
PS191
BAU
-8
SHiP
NuTeV
CHARM
-7
10-9
10
HNL mass (GeV)
NuTeV
BAU
10-10
1
Inverted hierarchy
10-6
-7
10
Seesaw
HNL mass (GeV)
Inverted hierarchy
10-6
10-11
FCC-ee
BBN
SHiP
10-9
10-10
BBN
FCC-ee
10-11
10-11
Seesaw
1
10
HNL mass (GeV)
Decay length: 10-100 cm
1012 Z 0
Seesaw
1
10-11
10
HNL mass (GeV)
10-100 cm
1013 Z 0
Seesaw
1
10
HNL mass (GeV)
0.01-500 cm
1013 Z 0
Moriond, March 29 2017 – p. 37
Conclusions
Moriond, March 29 2017 – p. 38
Perhaps, the 125 GeV Higgs and
neutrinos are telling us that the
fundamental interactions are relatively
simple from the very small to the very
high energy scale?
Moriond, March 29 2017 – p. 39
Perhaps, the 125 GeV Higgs and
neutrinos are telling us that the
fundamental interactions are relatively
simple from the very small to the very
high energy scale?
All observational drawbacks of the SM can be solved by the Higgs
boson interactions in the νMSM = SM + 3 neutral leptons
Moriond, March 29 2017 – p. 39
Perhaps, the 125 GeV Higgs and
neutrinos are telling us that the
fundamental interactions are relatively
simple from the very small to the very
high energy scale?
All observational drawbacks of the SM can be solved by the Higgs
boson interactions in the νMSM = SM + 3 neutral leptons
inflation - Higgs boson
Moriond, March 29 2017 – p. 39
Perhaps, the 125 GeV Higgs and
neutrinos are telling us that the
fundamental interactions are relatively
simple from the very small to the very
high energy scale?
All observational drawbacks of the SM can be solved by the Higgs
boson interactions in the νMSM = SM + 3 neutral leptons
inflation - Higgs boson
neutrino masses, dark matter and baryogenesis - Higgs + 3
HNLs
Moriond, March 29 2017 – p. 39
Theoretical challenges, similar to the
Standard Model:
UV completion, unification with gravity
Why the Higgs and HNL masses are so much smaller than the
Planck scale?
Why the cosmological constant (or dark energy) is so tiny?
Why θQCD is so small?
Origin and magnitude of Yukawa couplings
...
Moriond, March 29 2017 – p. 40
Experimental challenges:
Cosmology
Inflationary parameters. The Higgs inflation predictions:
Gaussian perturbations, ns = 0.967, r = 0.003
X-ray searches of decaying DM
Properties of DM. In the νMSM, depending on parameters,
the DM may contain the cold and warm components
simultaneously.
The number of relativistic species. For the SM or the νMSM,
this number (in terms of effective neutrino species) is
Nν = 3.046. Any deviation from it would signal the presence
of BSM or BνMSM physics.
Moriond, March 29 2017 – p. 41
Neutrino physics
Determine neutrino masses (or establish the best constraint
on them). The νMSM prediction: one of the active neutrino
P
−5
mν = 0.1 eV or
masses is below 10 eV, meaning that
= 0.06 eV , depending on neutrino mass hierarchy (inverted
or normal).
Prove the absence or presence of light sterile neutrinos ∼ 1
eV
Particle Physics
Top Yukawa coupling with accuracy 5 × 10−4 (δMt ≃ 100
MeV) (LHC? future e+ e− collider?)
HNL production and decays are highly suppressed –
dedicated experiments are needed:
Mass below ∼ 2 GeV - Intensity frontier, SHiP: CERN SPS.
Mass above ∼ 2 GeV - FCC in e+ e− mode in Z-peak, LHC
Moriond, March 29 2017 – p. 42
Backup slides
Moriond, March 29 2017 – p. 43
Higgs inflation with metastable
vacuum
The scale MP /ξ is the boundary between low energy and high energy
behaviours. Here the “jumps” of the coupling constants occur.
λ(MP /ξ) is small due to cancellations between fermionic and bosonic
loops: δλ can be of the order of λ
10
0.55
Non!critical
Dashed ∆yt % 0.025
Dotted ∆yt % !0.025
Critical
0.50
0
yt
103 Λ
5
0.45
!5
0.40
mh % 125.5 GeV
mt % 173.1 GeV
!10
10!10
10!8
10!6
10!4
ΚΜ
10!2
100
0.35 !8
10
mh % 125.5 GeV
mt % 173.1 GeV
10!6
10!4
0.01
1
ΚΜ
Moriond, March 29 2017 – p. 44
Higgs potential
V
vEW
µ0
MP
ξ
MP
χ
Moriond, March 29 2017 – p. 45
Symmetry restoration
8
8
1
M 2 Χ2 approx.
2
Exact potential
6
6
4
7
4
U
4
U0
10 U
U0
2
7
10 U
0
U0
2
T $ 8 x 1013 GeV
T $ 7 x 1013 GeV
T $ 6 x 1013 GeV
T $ 5 x 1013 GeV
T$0
2
0
!2
!2
!4
!0.3 !0.2 !0.1
0.0
0.1
103 ΚΧ
0
!0.1
0.0
0.1
ΚΧ
0.2
0.3
0.2
0.3
!4
0.00
0.05
0.10 0.15
103 ΚΧ
0.20
0.25
Reheating temperature TR ≃ 2 × 1014 GeV > T+ ≃ 7 × 1013 GeV,
Tc = 6 × 1013 GeV
System is trapped at the vacuum with zero Higgs field and does not go
to the false vacuum!
Predictions for critical indexes ns and r are the same:
ns = 0.97, r = 0.003
Moriond, March 29 2017 – p. 46
Effective field theory and neutrino masses
Neutrinos have non-zero masses - how to incorporate this into the
Standard Model? Effective field theory approach: low energy
Lagrangian can contain all sorts of higher-dimensional
SU(3)×SU(2)×U(1) invariant operators, suppressed by some
unknown scale Λ:
L = LSM +
∞
X
n=5
On
Λn−4
.
Majorana neutrino mass: from five-dimensional operator
O5 = Aαβ L̄α φ̃
φ
†
Lcβ
Neutrino mass matrix:
Mν ∼ Aαβ
v2
Λ
Moriond, March 29 2017 – p. 47
Crucial questions:
What is the physics behind
non-renormalizable terms?
What is the value of Λ ?
Moriond, March 29 2017 – p. 48
Common lore: origin of neutrino masses - existence of new unseen
particles; complete theory is renormalisable
Moriond, March 29 2017 – p. 49
Common lore: origin of neutrino masses - existence of new unseen
particles; complete theory is renormalisable
Higgs triplet with hypercharge 2 - direct contribution to neutrino
mass
Singlet Majorana fermions - effective contribution to neutrino mass
Moriond, March 29 2017 – p. 49
Common lore: origin of neutrino masses - existence of new unseen
particles; complete theory is renormalisable
Higgs triplet with hypercharge 2 - direct contribution to neutrino
mass
Singlet Majorana fermions - effective contribution to neutrino mass
φ
φ
N
ν
φ
ν
?
ν
φ
ν
Moriond, March 29 2017 – p. 49