lab-to-genesis how to find the origin of matter in …...introduction neutrino oscillations...

Introduction Neutrino oscillations Leptogenesis Experimental searches

LAB-TO-GENESIS

HOW TO FIND THE ORIGIN OF MATTER IN EXISTING EXPERIMENTS

Marco DrewesTU München

based onarXiv:1404.7114 [hep-ph],

Phys.Rev.Lett. 110 (2013) 6, 061801 ,JHEP 1303 (2013) 096 ,

Phys.Rev. D87 (2013) 093006and work in progress

2013 review: arXiv:1303.6912 [hep-ph] Int.J.Mod.Phys. E22 (2013) 1330019

Kosmologietag 2014, Bielefeld

1 / 17LAB-TO-GENESIS, HOW TO FIND THE ORIGIN OF MATTER IN EXISTING EXPERIMENTS


The Standard Model and General Relativity together explainalmost all phenomena in nature, but. . .

gravity is not quantized

a handful of observations remain unexplained

neutrino oscillations

baryon asymmetry of the universe

dark matter

geometry of the universe



Can we probe the New Physics empirically?



Neutrino masses: Seesaw mechanism

L = LSM + i ν̄R /∂νR − L̄LFνRΦ̃ − ν̄RF †LΦ̃† −1

2(ν̄c

RMMνR + ν̄RM†Mνc

R)

Majorana masses MM introduce new mass scale(s)

six (Majorana) mass eigenstates

two sets of mass states with small mixing θ � 1here θ = mDM−1

M = vFM−1M



Neutrino masses: Seesaw mechanism

L = LSM + i ν̄R /∂νR − L̄LFνRΦ̃ − ν̄RF †LΦ̃† −1

2(ν̄c

RMMνR + ν̄RM†Mνc

R)

Majorana masses MM introduce new mass scale(s)

six (Majorana) mass eigenstates

two sets of mass states with small mixing θ � 1here θ = mDM−1

M = vFM−1M

three light neutrinos νi ' Uν(νL + θνcR)i

mostly "active" SU(2) doubletmasses ∼ mν = θMMθT

three heavy neutrinos NI ' νR + θT νcL

mostly "sterile" singletsheavy masses MI ∼ MM



Can we probe this New Physics empirically?



plot from 1204.5379



Leptogenesis

fermion number violationsphalerons violate B, but conserve B − L at T > 140 GeVYukawa couplings F violate individual lepton flavour numbersin addition MM violates total lepton number



Leptogenesis


C and CP violationweak interaction violates Padditional complex phases in F violate CP



Leptogenesis


C and CP violationweak interaction violates Padditional complex phases in F violate CP

nonequilibrium

NI production

NI freezeout

NI decay

Y

Yeq

M/T

baryon asymmetry is generated during NI production at T > 140 9 / 17LAB-TO-GENESIS, HOW TO FIND THE ORIGIN OF MATTER IN EXISTING EXPERIMENTS


Leptogenesis during NI-freezeout/decay

Majorana fermions NI can decay into leptons or antileptons

The probabilities for both decays are different due to theCP-violation in F

decay violates total lepton number L

sphalerons convert part of L into B

Φ

lα

NI NJNINI

Φ

lαlαΦ

Φlβ

Φ

lβ

NJ

Fukugita/Yanagida 1986



Leptogenesis during NI production

CP-violating oscillations amongst NI generate L 6= 0 during theirthermal production

sphalerons convert part of L into B

Akhmedov/Rubakov/Smirnov 1998, Asaka/Shaposhnikov 2006

With two RH neutrinos this requires a mass degeneracy ∼ 10−3

Canetti/MaD/Frossard/Shaposhnikov 1208.4607

With three RH neutrinos no such degeneracy is needed!

MaD/Garbrecht 1206.5537



Why is 2 RH neutrinos different from 3 RH neutrinos?

asymmetry is larger if generated at earlier times⇒ grows with |FαI | as ΓI = (F †F )IIγav T

but washout rates Γα = (FF †)ααγav T also grow with |FαI |



Why is 2 RH neutrinos different from 3 RH neutrinos?

asymmetry is larger if generated at earlier times⇒ grows with |FαI | as ΓI = (F †F )IIγav T

but washout rates Γα = (FF †)ααγav T also grow with |FαI |

two RH neutrinos:NI-coupling to all flavours governed by only one parameter

NI coupling to different flavours "tied together"large ΓI necessarily imply large washout for all flavoursBAU can only be explained if |FαI | are very smallCP-violation must be enhanced by mass degeneracy ∼ 10−3

three RH neutrinos:individual |FαI | can be very different in size

flavour asymmetric washoutasymmetry in individual flavour(s) can survive in spite of observablylarge NI -mixing



Experimental signatures

W

N0

i

W

q1

q2

q3

q4

lα

lβ




for 5 GeV < MI < mZ

NI produced in Z -decays (e.g. at LEP)same sign dilepton signal




for 5 GeV < MI < mZ


for 2GeV < MI < 5 GeV (LHCb, BELLE, SHIP)

NI produced in B-meson decaysB− → NIµ

− → π+µ−µ− etc give same sign dilepton signalsensitivity ∼

√Lint

BELLE can also do "peak searches" for missing 4-momentumsensitivity ∼ Lint




for 5 GeV < MI < mZ


for 2GeV < MI < 5 GeV (LHCb, BELLE, SHIP)

NI produced in B-meson decaysB− → NIµ

− → π+µ−µ− etc give same sign dilepton signalsensitivity ∼

√Lint

BELLE can also do "peak searches" for missing 4-momentumsensitivity ∼ Lint

for MI < 2 GeV (SHIP)

NI produced in D-meson decaysexisting bounds very strong⇒ can only be improved by dedicated fixed target experiments



Leptogenesis with two RH neutrinos

0.2 0.5 1.0 2.0 5.0 10.010-12

10-10

10-8

10-6

M @GeVD

U2

BAU

BAU

Seesaw

BBN

PS191

NuTeV

CHARM

U2 ≡ trθ†θ

Canetti/MaD/Frossard/Shaposhnikov 1208.4607



Leptogenesis with three RH Neutrinos

1 2 3 4 510−9

10−7

10−5

0.001

past experiments

BELLE

LHCb

baryogenesis

M2 [GeV]

U2 µ

Canetti/MaD/Garbrecht 1404.7114



Probing the origin of matter in the laboratory

W

N0

i

W

q1

q2

q3

q4

lα

lβ

two RH neutrinos three RH neutrinos

baryogenesis requires mass degeneracy works without degeneracy

lab searches SHIP 1310.1762 LHCb, BELLE, SHIP,. . .

Smirnov/Kersten, Atre/Han/Pascoli/Zhang, Canetti/MaD/Shaposhnikov, . . .


lab-to-genesis how to find the origin of matter in …...introduction neutrino oscillations...

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