Low-scale baryogenesis
@Vietnam (2014/08/01)
Takehiko Asaka (Niigata Univ.)
Xth Rencontres du VietnamFlavor Physics Conference
ICISE, QUY NHON, VN(27 July-2 August 2014)
Baryon asymmetry of the universe (BAU)
2014/08/01
[Strumia 06]
Planck 2013 resultsarXiv:1303.5076
Baryon number densityEntropy density
Baryon Number = (# of baryons) (# of antibaryons)
:Bn:s
Takehiko Asaka (Niigata Univ.)
2
Introduction Neutrino mass scales
Atmospheric: ≃ 2.4 10 eV Solar: ≃ 7.5 10 eV⇒ Need for physics beyond the SM !
Important questions: “What is the origin of neutrino masses?” “What is the implications of it?” “How do we test it experimentally?”
2014/08/01Takehiko Asaka (Niigata Univ.)
3
Extension by RH neutrinos
Seesaw mechanism ( Φ ≪ )
Light active neutrinos , ,→ explain neutrino oscillations
Heavy neutral leptons , , Mass Mixing Θ /
+ h.c.2
cMR R R R R
ML i F Lμμδ ν γ ν ν ν ν= ∂ − Φ −
0 01 1( , ) . ( , ) . .02 2
c cDc L
L R TD R
c
M M
M ML h c h c
M NMN
Mννν ν
ννν
− = + = +
1T
D DM
M M MMν = −
1 2 3( , , )TU M U diag m m mν =
mixing in CC current
Minkowski ’77Yanagida ’79Gell-Mann, Ramond, Slansky ‘79Glashow ‘79
2014/08/01Takehiko Asaka (Niigata Univ.)
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Scale of Majorana mass The simplest case: one pair of and
221 /TD D M
M
M M M F M MMν ν= − = Φ
2atmM mν = Δ
Majorana Mass
Neut
rino
Yuka
wa
Coup
ling
-12
-10
-8
-6
-4
-2
0
2
-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16
log 1
0(F)
log10(MM/GeV)
tF F=
eF F=
2014/08/01Takehiko Asaka (Niigata Univ.)
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Scale of Majorana mass The simplest case: one pair of and
221 /TD D M
M
M M M F M MMν ν= − = Φ
Majorana Mass
Neut
rino
Yuka
wa
Coup
ling
-12
-10
-8
-6
-4
-2
0
2
-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16
log 1
0(F)
log10(MM/GeV)
tF F=
eF F=
Baryogenesis via leptogenesisFukugita, Yanagida ‘86
2014/08/01Takehiko Asaka (Niigata Univ.)
6
Talk by Stephane Lavignac
Scale of Majorana mass The simplest case: one pair of and
221 /TD D M
M
M M M F M MMν ν= − = Φ
Majorana Mass
Neut
rino
Yuka
wa
Coup
ling
-12
-10
-8
-6
-4
-2
0
2
-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16
log 1
0(F)
log10(MM/GeV)
tF F=
eF F=
Baryogenesis via leptogenesisFukugita, Yanagida ‘86
2014/08/01Takehiko Asaka (Niigata Univ.)
7
Scale of Majorana mass The simplest case: one pair of and
221 /TD D M
M
M M M F M MMν ν= − = Φ
Majorana Mass
Neut
rino
Yuka
wa
Coup
ling
-12
-10
-8
-6
-4
-2
0
2
-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16
log 1
0(F)
log10(MM/GeV)
tF F=
eF F=
Baryogenesis via leptogenesisFukugita, Yanagida ‘86
Baryogenesis via neutrino osc.
Akhmedov, Rubakov, Smirnov ‘98
TA, Shaposhnikov ‘05
2014/08/01Takehiko Asaka (Niigata Univ.)
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The νMSM :no new mass scale between and
Lightest one among 3 heavy neutral leptons with keVmass can be dark matter !!
Oscillation of heavy neutral leptons and can generate baryon asymmetry of the universe !
Dark matter can be tested by cosmic X-ray obs.
Physics of heavy neutral leptons and can be tested by experiments !!!
Dodelson, Widrow ‘94,…
Akhmedov, Rubakov, Smirnov ’98, TA, Shaposhnikov ‘05
≃ 4 10 100GeV 0.05eVTA, Blanchet, Shappshnikov ‘05,TA, Shaposhnikov ‘05
2014/08/01Takehiko Asaka (Niigata Univ.)
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Talk by Oleg Ruchayskiy
Baryogenesis via Neutrino Oscillation
§
2014/08/01Takehiko Asaka (Niigata Univ.)
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Baryogenesis in the νMSM
B and L violations B violation due to EW sphaleron L violation due to Majorana masses
negligible for baryogenesis temperature since ≲ C and CP violations
1 CP phase in quark sector 6 CP phases in lepton sector
3 CP phases associated with , are relevant for baryogenesis Out of equilibrium
No 1st order EW phase transition as in the SM , can be out of equilibrium for ≳ ,if Yukawa couplings are small enough
Conditions for Baryogenesis (Sakharov ‘67)
2014/08/01Takehiko Asaka (Niigata Univ.)
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Baryogenesis via neutrino osc. Oscillation of HNLs can be a source of BAU
Oscillation starts at ~ /
Asymmetries are generated since evolution rates of and are different due to CPV
Akhmedov, Rubakov, Smirnov (’98) / TA, Shaposhnikov (‘05)Shaposhnikov (’08), Canetti, Shaposhnikov (‘10)TA, Ishida (‘10), Canetti, Drewes, Shaposhnikov (’12), TA, Eijima, Ishida (‘12)Canetti, Drewes, Shaposhnikov (‘12), Canetti, Drewes, Frossard, Shaposhnikov (‘12)
N NL
Medium effects
8
12
Key points
Baryogenesis via leptogenesis
Baryogenesis via neutrino osc.
BB
LL
sphaleron
sphaleron
B L B L
2014/08/01Takehiko Asaka (Niigata Univ.)
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Evolution of asymmetries
2014/08/01
[Kuzmin, Rubakov, Shaposhnikov]
Shaleron converts Δ partially into baryon asymmetry
8.55~9.00 10[Planck 2013]
Yield of BAU depends on (even PMNS matrix !!) and masses, especially, CP violating parameters and mass difference~ /
2.5 10 Δ
Takehiko Asaka (Niigata Univ.)
14
BAU and Phases and
21/11/2012
0
0.5
1
0 0.5 1 1.5 2
η/π
δ/π
-2E-902E-9
4E-96E-9
8E-9
-0.5
0
0.5
0 0.5 1 1.5 2
Reω
/π
δ/π
-8E-9
-6E-9-4E-9
-2E-90
8E-9
6E-94E-9
2E-9
IH case
Yield of BAU depends on (even PMNS matrix !!) and masses, especially, CP violating parameters and mass difference~ /Takehiko Asaka (Niigata Univ.)
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Baryogenesis via neutrino osc.Region accounting for
TA, Eijima ‘13
10-410-310-210-1100101102103104105106107
10-4 10-3 10-2 10-1 100
ΔΜ
[eV
]
MN[GeV]
NHIH
8.55-9.00) 10IH
NH
Canetti, Shaposhnikov ‘10
2.1 MeV (NH) 0.7 MeV (IH)
2014/08/01Takehiko Asaka (Niigata Univ.)
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Direct search experiment PS191
Beam dump experimentperformed at CERN in 1984
Production Detection
Upper bounds mixing elements Θ⇒ Lower bound on lifetime of ,
[Bernardi et al ‘86, ’88]
, → ⟶ ℓ ℓ , ℓ
2014/08/01Takehiko Asaka (Niigata Univ.)
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Constraints on light RH neutrinos
10-3
10-2
10-1
100
200 300 400τ N
[sec
]MN[MeV]
10-3
10-2
10-1
100
200 300 400
τ N [s
ec]
MN [MeV]
Cosmology
Direct search
Normal hierarchy Inverted hierarchy
MeV MeVMeV
TA, Eijima ‘13
PS191
2014/08/01Takehiko Asaka (Niigata Univ.)
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Search for heavy neutral leptons (HNLs)
§
2014/08/01Takehiko Asaka (Niigata Univ.)
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SHIP A new fixed-target experiment at the CERN SPS accelerator is
proposed that will use decays of charm mesons to search for Heavy Neutral Leptons
arXiv:1310.1762
2014/08/01Takehiko Asaka (Niigata Univ.)
20Talk by Nicola Serra
Search for HNLs at T2KProduction of Detection of →ℓ → ℓ ℓ
TA, Eijima, Watanabe[JHEP1303 (2013) 125]
PS191
T2K 61.25m 9m10 POT
0.86 10 POT
2014/08/01Takehiko Asaka (Niigata Univ.)
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Sensitivity: PS191 vs T2K
T2K at 10 POT has a better sensitivity than PS191 (0.86 10 POT) !
PS191
T2K
Takehiko Asaka (Niigata Univ.) 02, May/2014
TA, Eijima, Watanabe ‘13
22
Summary We have considered the νMSM with three right-handed neutrinos
which are lighter than weak scale.
We have found the possible region for neutrino oscillations and BAU, allowed from search and cosmological constraints.
Search for these heavy neutral leptons are crucial to solve the origin of neutrino masses as well asthe mysteries of our universe, DM and BAU !!!
Neutrino masses by seesaw mechanism Dark matter (lightest HNL with ~keV mass) Baryogenesis via neutrino oscillations of , Direct search of , is possible
163 MeV (NH)188 269 MeV and 285MeV (IH)
2014/08/01Takehiko Asaka (Niigata Univ.)
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Backup
2014/08/01Takehiko Asaka (Niigata Univ.)
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BBN constraint on lifetime Long-lived , may spoil the success of BBN
Speed up the expansion of the universe
, ⇒ p-n conv. decouples earlier ⟹ overproduction of He
Distortion of spectrum of active neutrinos , → ̅ , , … Additional neutrinos may not be thermalized⇒ Upper bound on lifetime of ,
Dolgov, Hansen, Rafflet, Semikoz (’00) One family case:
⟷ , …
0.1 secfor2014/08/01Takehiko Asaka (Niigata Univ.)
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Constraints on HNLs and Canetti, Drewes, Frossard, Shaposhnikov ‘13
NH IH
Gorbunov and Shaposhnikov ’07 [arXiv:0705.1729]Atre, Han, Pascoli, Zhang ‘09 [arXiv:0901.3589]See
2014/08/01Takehiko Asaka (Niigata Univ.)
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Neutrino Yukawa couplings for ,1/2 1/2
PMNS /NF U D Dν= Ω Φ
2 31/2 diag( , )ND M M=
1 2 31/2 diag( , , )0D m m mν = =
0 0
cos sin
sin cos
ω ωω ωξ ξ
Ω = −
12 13 12 13 13
PMNS 23 12 23 12 13 23 12 23 12 13 23 13
23 12 23 12 13 23 12 23 12 13 23 13
1
1
i
i i i
i i
c c s c s e
U c s s c s e c c s s s e s c e
s s c c s e s c c s s e c c
δ
δ δ η
δ δ
−
= − − −
− − −
[Casas, Ibarra ’01]
Parameters of active neutrinos
Parameters of sterile neutrinos
: active ν masses
: sterile ν masses
1ξ = ±
Dirac phase δ
Imω
(in NH)
Majorana phase η
:complex number
2014/08/01Takehiko Asaka (Niigata Univ.)
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