pfig meff active ih v2 - · 2015. 5. 16. · pfig_meff_active_ih_v2.eps author: asaka subject:...

レプトン数の破れから探る宇宙バリオン数⽣成機構の解明

@Kobe University (2015/05/16)

淺賀岳彦 (新潟⼤学)

新学術領域「宇宙の歴史をひもとく地下素粒⼦原⼦核研究」

2015年領域研究会 @神⼾⼤学百年記念館（2015/05/15~17）

Motivation

2015/05/16

2

Takehiko Asaka (Niigata Univ.)

Origin of neutrino masses

Neutrino mass scales Atmospheric: ≃ 2.4 10 eV Solar： ≃ 7.5 10 eV

⇒ Clear signal for new physics beyond the SM !

Important questions: What is the origin of neutrino masses? What are the implications to other physics? How do we test it experimentally?

3

2015/05/16Takehiko Asaka (Niigata Univ.)

RH Neutrinos and Seesaw Mechanism

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 L

0 01 1( , ) . ( , ) . .02 2

c cDc L

L R TD R

c

M M

M ML h c h c

M NMN

M

1T

D DM

M M MM

1 2 3( , , )TU M U diag m m m

mixing in CC current

Minkowski ʼ77Yanagida ʼ79Gell-Mann, Ramond, Slansky ʻ79Glashow ʻ79


4

Review of Particle Physics


5

Yukawa Coupling and Mass of HNL


6

10-1410-1310-1210-1110-1010-910-810-710-610-510-410-310-210-1100101102

10-10 10-5 100 105 1010 1015 1020

F

MN [GeV]

Φ5 10 GeV

Seesawdoes not work !

Yukawa Coupling and Mass of HNL


7

10-1410-1310-1210-1110-1010-910-810-710-610-510-410-310-210-1100101102

10-10 10-5 100 105 1010 1015 1020

F

MN [GeV]

Φ5 10 GeV

Seesawdoes not work ! Leptogenesis

(Fukugita, Yanagida ʻ86)

Baryogenesis via neutrino oscillation(Akhmedov, Rubakov, Smirnov ʼ98,

TA, Shaposhnikov ʼ05)

Mixing and Mass of HNL


8

10-30

10-25

10-20

10-15

10-10

10-5

100

10-10 10-5 100 105 1010 1015 1020

|Θ|2

MN [GeV]

Θ 5 10 GeV

Leptogenesis

Baryogenesis via neutrino oscillation

Various Physics of HNLs


9

10-30

10-25

10-20

10-15

10-10

10-5

100

10-10 10-5 100 105 1010 1015 1020

|Θ|2

MN [GeV]

MSM


DarkMatter

TA, Blanchet, Shaposhnikov ʻ05,TA, Shaposhnikov ʻ05

Target

2015/05/16

10


Baryon asymmetry of the universe (BAU)


11

[Strumia 06]

Planck 2015[arXiv:1502.01589]

Baryon number densityEntropy density

Baryon Number = (# of baryons) (# of antibaryons)

:Bn:s

Conditions for baryogenesis


12

Sakharov (1967)

(1) Baryon number B is violated

(2) C and CP symmetries are violated

(3) Out of thermal equilibrium

“According to our hypothesis, the occurrence of Casymmetry is the consequence of violation of CP invariancein the nonstationary expansion of the hot Universe duringthe superdense stage, as manifest in the difference betweenthe partial probabilities of the charge-conjugate reactions.”

Yukawa Coupling of HNL


13

10-1410-1310-1210-1110-1010-910-810-710-610-510-410-310-210-1100101102

10-10 10-5 100 105 1010 1015 1020

F

MN [GeV]

Φ5 10 GeV

Seesawdoes not work !

Leptogenesis


Baryogenesis conditions


14

B and L violations (B+L) violation due to sphaleron L violation due to Majorana masses

Majorana masses < 100 GeV negligible for T>100 GeV

C and CP violations 1 CP phase in quark sector 6 CP phases in lepton sector

Baryogenesis conditions


15

Out of equilibrium No 1st order EW phase transition as in the SM Heavy neutral leptons can be out of equilibrium,

if Yukawa couplings are small enough To ensure this condition up to T〜100GeV

L

tR QL

N

The model with HNLs with MN<100 GeV can realize all three conditions for baryogenesis

GeV[TA, Shaposhnikov ʼ05]

Baryogenesis via Neutrino Oscillation

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 (ʼ98) / TA, Shaposhnikov (ʻ05)Shaposhnikov (ʼ08), Canetti, Shaposhnikov (ʻ10)TA, Ishida (ʻ10), Canetti, Drewes, Shaposhnikov (ʼ12), TA, Eijima, Ishida (ʻ12)Canetti, Drewes, Shaposhnikov (ʻ12), Canetti, Drewes, Frossard, Shaposhnikov (ʻ12)

N NL

Medium effects

8

∗


16

Evolution of Each Asymmetry


17

Active Sector Sterile Sector

2.2 TeV

Evolution of Asymmetries


18

[Kuzmin, Rubakov, Shaposhnikov]

Shaleron converts L partially into baryon asymmetry

28 079 totB L

42.5 10 ( )Btot W

n L Ts

. .[Planck 2013]

Baryogenesis Region

Region accounting for TA, Eijima ʻ13

10-410-310-210-1100101102103104105106107

10-4 10-3 10-2 10-1 100

ΔΜ

[eV

]

MN[GeV]

NHIH

8.55-9.00) 10

IH

NH

Canetti, Shaposhnikov ʻ10

2.1 MeV (NH) 0.7 MeV (IH)


19

Constraints on HNLs


TA, Eijima, Takeda ʻ14

Direct Search

Cosmology

20

Task

2015/05/16

21


Research Task


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Target:HNLs for seesaw mechanism and baryogenesis Quasi-degenerate with 0.1 10 GeV Mixing elements Θ / Majorana fermions

⟹ induce Lepton Number Violating (LNV) processes

Task:Study various tests for LNV by HNLs !

Neutrinoless double beta decay


23

0 2 decay: , → 2, 2 Clear signal of LNV ! Effective neutrino mass

[W.H. Furry 1939]

, ,

…

10-4

10-3

10-2

10-1

100

10-6 10-5 10-4 10-3 10-2 10-1 100

|mef

f|ν [eV

]

mνlightest [eV]

NH

10-4

10-3

10-2

10-1

100

10-6 10-5 10-4 10-3 10-2 10-1 100

|mef

f|ν [eV

]

mνlightest [eV]

IH

Effective neutrino mass

HNLs may give a significantcontribution to !

, ,

, ,

Θ

active neutrinos heavy neutral leptons

[Blennow, Frenandez-Martinez,Pavon, Mnendez ʼ10]

/ 0


24

Θ

Θ

in the MSM 25

DM gives negligible contribution since Θ is very small Lightest gives negligible contribution since 10 eV Heavier , give destructive contribution to active ʼs one

10-5

10-4

10-3

10-2

10-1

10-2 10-1 100 101

|meff|[eV

]

MN[GeV]

10-5

10-4

10-3

10-2

10-1

10-2 10-1 100 101

|meff|[eV

]

MN[GeV]

NH IHTA, Eijima, Ishida ʻ11

, ,

, ,

Θ

Bezrukov ʼ05TA, Eijima, Ishida ʻ11

Active neutrinos Heavy neutral leptons


in the MSM


26

Constraints from search experiments and cosmology restrict the predicted range of effective neutrino mass

NH

IH10-4

10-3

10-2

10-1

100 200 300 400|m

eff|

[eV

]MN [MeV]

NH

IH

TA, Eijima, Ishidapreliminary

0.879 3.66 meV

13.8 47.9 meV

Inverse neutrinoless double beta decay


27

collision is an option of ILC⇒ test of LNV process:

Tasks Estimate → by HNLs for seesaw mechanism

and baryogenesis Study correlation between → and BAU

[T. G. Rizzo 1982]

→

HNLs can be produced by CC interaction⇒ Tests for LNV decays of HNLs → → ′ @ LHC, ILC, … → → @ Super-KEKB, LHCb → → @ J-PARC …

LNV decays of HNL


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Summary

2015/05/16

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Summary

Heavy neutral leptons (right-handed neutrinos) below the electroweak scale are well-motivated particles physics beyond the standard Model. Seesaw mechanism for neutrino masses Baryogenesis via neutrino oscillation Dark matter (sterile neutrino dark matter)

We study various tests for LNV by such heavy neutral leptons Neutrinoless double beta decay Inverse neutrinoless double beta decay ( → ) LNV decays of HNLs ( → → , … )


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⇒understand the origin of neutrino masses as well as the origin of matter of our universe!

pfig meff active ih v2 - · 2015. 5. 16. · pfig_meff_active_ih_v2.eps author: asaka subject:...

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