Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://qfthep.sinp.msu.ru/talks2013/QFTHEP-2013.pdf Äàòà èçìåíåíèÿ: Wed Jun 26 10:22:35 2013 Äàòà èíäåêñèðîâàíèÿ: Thu Feb 27 20:12:48 2014 Êîäèðîâêà:

I N R

Searches for GeV-scale sterile neutrinos with CERN SPS proton beam

Dmitry Gorbunov
Institute for Nuclear Research of RAS, Moscow

XXIst International Workshop on Quantum Field Theory and High Energy Physics, St.-Petersburg, Repino, 26.06.2013
Dmitry Gorbunov (INR) GeV-scale sterile neutrinos at CERN 26.06.2013, QFTHEP'2013 1 / 16


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Phenomenological problems of the Standard Model
Gauge fields (interactions) ­ , W ± , Z , g Three generations of matter: L = eL , eR ; Q = L Describes
all experiments dealing with electroweak and strong interactions
uL dL

, dR , u

R

Does not describe
Neutrino oscillations : active neutrino masses via mixing Dark matter (DM ) : sterile neutrino as DM Bar yon asymmetr y : leptogenesis via sterile neutrino decays or oscillations

Sterile neutrinos explain the oscillations and the cosmological problems

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

2 / 16


I N R

Phenomenological problems of the Standard Model
Gauge fields (interactions) ­ , W ± , Z , g Three generations of matter: L = eL , eR ; Q = L Describes
all experiments dealing with electroweak and strong interactions
uL dL

, dR , u

R

Does not describe
Neutrino oscillations : active neutrino masses via mixing Dark matter (DM ) : sterile neutrino as DM Bar yon asymmetr y : leptogenesis via sterile neutrino decays or oscillations

Sterile neutrinos explain the oscillations and the cosmological problems

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

2 / 16


I N R

Phenomenological problems of the Standard Model
Gauge fields (interactions) ­ , W ± , Z , g Three generations of matter: L = eL , eR ; Q = L Describes
all experiments dealing with electroweak and strong interactions
uL dL

, dR , u

R

Does not describe
Neutrino oscillations : active neutrino masses via mixing Dark matter (DM ) : sterile neutrino as DM Bar yon asymmetr y : leptogenesis via sterile neutrino decays or oscillations

Sterile neutrinos explain the oscillations and the cosmological problems

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

2 / 16


I N R

Sterile neutrinos: NEW ingredients
One of the optional physics beyond the SM: sterile: new fermions uncharged under the SM gauge group neutrino: explain obser ved oscillations by mixing with SM (active) neutrinos Attractive features: possible to achieve within renormalizable theory only N = 2 Majorana neutrinos needed baryon asymmetr y via leptogenesis dark matter (with N 3 at least) light(?) sterile neutrinos might be responsible for neutrino anomalies. . . ? Disappointing feature: Major par t of parameter space is UNTESTABLE
Dmitry Gorbunov (INR) GeV-scale sterile neutrinos at CERN 26.06.2013, QFTHEP'2013 3 / 16


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Active neutrino masses without new fields
Dimension-5 operator L = 2

L

(5)

=

L F 4

L

¯ H H Lc + h.c. ~
in a unitar y gauge

~ L are SM leptonic doublets, = 1, 2, 3, Ha = ab Hb , a, b = 1, 2; H T = 0, (v + h)/ 2 and

L
hence

(5)

=

L v 2 F ¯c + h.c. 4 2 3 â 10-3 eV2 2 matm
1/2

3 â 10 GeV â L â

14

The model has to be UV-completed at the neutrino scale < . . .

What is beyond the neutrino scale ? Why neutrino scale, 1 eV, is so low ?
Dmitry Gorbunov (INR) GeV-scale sterile neutrinos at CERN 26.06.2013, QFTHEP'2013 4 / 16


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Seesaw mechanism: M
With mactive

N

1 eV

(Type I)

1 eV we work in the seesaw (type I) regime:

When Higgs gains H = v / 2 we get in neutrino sector

MNI c ~ LN = N I i / NI - f I L H NI - N I NI + h.c. 2 ^ f v 2 ( , . . . N . . .) 1 1 ^ MN

0 MNI c f I c N I NI + h.c. = 1 , . . . N 1 . . . ^ VN = v NI + f 2 2 v
Then for MN ^ MD = v
^ f 2

T

2

we find the eigenvalues:
D

seesaw at work
2

^ ^ ^ MN and M = -M
Mixings: flavor state = U i i + I N
I

1 ^D v M f2 2 MN ^N MN M

MN

active-active mixing: active-sterile mixing:
Dmitry Gorbunov (INR)

^ U M U = diag (m1 , m2 , m3 )
I



(M D ) I ^ v =f MN MN

1
5 / 16

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013


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Where is sterile neutrino scale?
eigenvalues: ^ ^ ^ MN and M = -M
D

1 ^D v2 M f2 ^ MN MN

MN

SEESAW says nothing about the sterile neutrino scale MN !
3·10-3 eV2 2 matm 1 /2

Unitarity:

f

1

=

MN

3 â 10

14

GeV â

- in (LH )2 /
MN I 2

Integrating out sterile neutrinos get dim-5 operator

~ -f I L H NI -

N I NI f 2 (LH )2 /MN

c

SM Higgs without NP at EW-scale favors sterile neutrinos at EW-scale (or below) !

Majorana mass violates scale-invarinace

=

finite corrections

2 2 mh f 2 MN 2 2 mh f 2 2 MN

Scale invariance helps to abandon infinite corrections

In SM scale invariance is broken by the Higgs mass and running of coupling constants µ 2 ^ Tµ ( ) â O + mh + 2 â h2 = quadratic divergences are irrelevant
W.Bardeen (1995) Dmitry Gorbunov (INR) GeV-scale sterile neutrinos at CERN 26.06.2013, QFTHEP'2013 6 / 16


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Sterile neutrinos: MNI violate lepton symmetry
Most general renormalizable with 2(3. . . ) right-handed neutrinos NI MNI c ~ LN = N I i / NI - f I L H NI - N NI + h.c. 2I Parameters to be determined from experiments
9(7): active neutrino sector oscillation experiments 3 ij : oscillation experiments 1 CP-phase: oscillation experiments 2(1) Majorana phases: 0 ee, 0 µ µ 3 H 3 He + e + , ¯e 1(0) m : cosmology, . . .
2 2 mij :



11: N = 2 sterile neutrinos 18: N = 3 sterile neutrinos: ( works if m = 0 !!!) 3: Majorana masses MNI 2: Majorana masses MNI 15: New Yukawa couplings f I 9: New Yukawa couplings f I which form which form 3: Dirac masses M D = f H 2: Dirac masses M D = f H 3+3: mixing angles 3+1: mixing angles 3+3: CP-violating phases 2+1: CP-violating phases 9 new parameters in total 4 new parameters in total both BAU and DM are possible help with leptogenesis

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

7 / 16


I N R

Sterile neutrinos: MNI violate lepton symmetry
Most general renormalizable with 2(3. . . ) right-handed neutrinos NI MNI c ~ LN = N I i / NI - f I L H NI - N NI + h.c. 2I Parameters to be determined from experiments
9(7): active neutrino sector oscillation experiments 3 ij : oscillation experiments 1 CP-phase: oscillation experiments 2(1) Majorana phases: 0 ee, 0 µ µ 3 H 3 He + e + , ¯e 1(0) m : cosmology, . . .
2 2 mij :



11: N = 2 sterile neutrinos 18: N = 3 sterile neutrinos: ( works if m = 0 !!!) 3: Majorana masses MNI 2: Majorana masses MNI 15: New Yukawa couplings f I 9: New Yukawa couplings f I which form which form 3: Dirac masses M D = f H 2: Dirac masses M D = f H 3+3: mixing angles 3+1: mixing angles 3+3: CP-violating phases 2+1: CP-violating phases 9 new parameters in total 4 new parameters in total both BAU and DM are possible help with leptogenesis

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

7 / 16


I N R

Sterile neutrinos: MNI violate lepton symmetry
Most general renormalizable with 2(3. . . ) right-handed neutrinos NI MNI c ~ LN = N I i / NI - f I L H NI - N NI + h.c. 2I Parameters to be determined from experiments
9(7): active neutrino sector oscillation experiments 3 ij : oscillation experiments 1 CP-phase: oscillation experiments 2(1) Majorana phases: 0 ee, 0 µ µ 3 H 3 He + e + , ¯e 1(0) m : cosmology, . . .
2 2 mij :



11: N = 2 sterile neutrinos 18: N = 3 sterile neutrinos: ( works if m = 0 !!!) 3: Majorana masses MNI 2: Majorana masses MNI 15: New Yukawa couplings f I 9: New Yukawa couplings f I which form which form 3: Dirac masses M D = f H 2: Dirac masses M D = f H 3+3: mixing angles 3+1: mixing angles 3+3: CP-violating phases 2+1: CP-violating phases 9 new parameters in total 4 new parameters in total both BAU and DM are possible help with leptogenesis

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

7 / 16


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MSM:

2 GeV-scale & 1 keV-scale neutrinos
2 GeV-scale seesaw neutrinos DM: 1-50 keV
mixing with active neutrinos: need two! N1 > U little contribution to m signature in X-rays N1
a

T.Asaka, S.Blanchet, M.Shaposhnikov (2005)

give masses and mixing to active neutrinos

violate CP need two! out-of-equilibrium oscillations a N2,3 2 need ver y small mixing I 1 in the early Universe redistribute lepton charge need degeneracy: MN2,3 MN2 , MN3
1
10-6

produced in early Universe in plasma needs strong fine-tuning
10-7 N > DM
1

BBN

NRP

Seesaw
0.01

10-8 Phase-space density constraints

X-ray constraints

Seesaw I
BAU

NH
sin2(21)

10-9 10-10 10-11 10
-12

L6 =25
L6 =70
BBN limit:
max L6 =700

s

10

4

N

LBBN 6

BAU

I

10-13 10-14

= 2500

N < DM
1

10

6

10-15

1

5 M1 [keV]

10

50

10

8

easily produced by inflaton XNN
0.2 0.5 M GeV 1.0 2.0 5.0

M.Shaposhnikov, I.Tkachev (2006), F.Bezrukov, D.G. (2009) 26.06.2013, QFTHEP'2013 8 / 16

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN


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Direct searches for sterile neutrinos: 2 approaches
Weak decays due to mixing
Ds µ N2,3 D µ N2,3 µ
N2,3 µ µ e e

µ
N µ
2,3

µ

Production in beam-dump experiments
l l
target

µ
PT

hadrons

P T

l

N

beam target

L
detector

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

9 / 16


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MSM parameter space
CHARM 10
6

2 N U

2
NuTeV

NuTeV
PS191

10

6

CHARM
PS191

BAU BAU
BBN

U

BAU
10 10

U

10

8

10

8

BBN
BAU
Seesaw

2

10

2

Seesaw

10

10

12

10 0.2 0.5 1.0 M GeV 2.0 5.0 10.0

12

0.2

0.5

1.0 M GeV

2.0

5.0

10.0

D.G, M.Shaposhnikov (2007)

Br (D lN ) Br (Ds lN ) Br (D KlN ) Br (Ds lN ) Br (D K lN ) Br (B D lN ) Br (Bs
Ds

2 · 10-8 3 · 10 2 · 10
-7 -7
s

L.Canetti, M.Drewes, M.Shaposhnikov (2012)
1 BBN

Seesaw
0.01

Seesaw I
BAU

NH

5 · 10

-8

10

4

N

BAU

I

7 · 10-8 4 · 10 3 · 10
-7 -7

10

6

10

8

0.2

0.5 M GeV

1.0

2.0

5.0

lN )

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

10 / 16


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Neutrino production in pp-collisions: meson decays
Experiment CNGS NuMi T2K NuTeV E , GeV 400 120 30 800 NPOT , 10 4.5 5 100 1
19

c /tot 0.45 â 10-3 1 â 10-4 0.5 â 10-5 1 â 10-3

b /tot 3 â 10-8 10-10 10-12 2 â 10-7

Pure geometrical factor as compared to CHARM LBNE PoT 1.0 â 1022 2.5 â 1018
22 18

detector length

distance to target 500 m 480 m 480 500
2

beam energy 120 GeV 400 GeV 120 400
2

detector area 4â4 m 3â3 m
2 2

charm production 1.0 â 10-4 4.5 â 10-4

HiResM CHARM
HiResM Nsignal

35 m 34 m 35 â 34

N

CHARM signal

=

1.0 â 10 2.5 â 10
2 N2

â

â

â

4 â 4 1.0 â 10-4 â 130 3 â 3 4.5 â 10-4

N

signal

â

2 N2

2 order of magnitude improvement in N2
GeV-scale sterile neutrinos at CERN 26.06.2013, QFTHEP'2013 11 / 16

Dmitry Gorbunov (INR)


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CNGS site is free after OPERA

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

12 / 16


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MSM parameter space for MN < 2 GeV
NuTeV CHARM 10
6 6

NuTeV
PS191

10

CHARM
PS191

BAU BAU
BBN

U

BAU
10 10

U

10

8

10

8

BBN
BAU
Seesaw

2

10

2

Seesaw

10

10

12

10 0.2 0.5 1.0 M GeV 2.0 5.0 10.0

12

0.2

0.5

1.0 M GeV

2.0

5.0

10.0

D.G, M.Shaposhnikov (2012) S.Gninenko, D.G, M.Shaposhnikov (2012)

L.Canetti, M.Drewes, M.Shaposhnikov (2012)

L=100 m

l 5 m
l µ

l|| 100 m

l

target

hadrons

PT

P T

l

N

beam target

L
detector

Production rate U ,
Dmitry Gorbunov (INR)

2

Decay rate U

2
13 / 16

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013


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To fully explore the region MN < 2 GeV
E/HCAL

Beam dump V P, 400 GeV T

DV

ST

µ
Ds N

µ

NPoT

1020 ,

ltotal

3 km

multisectional detector (presumably on surface)

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

14 / 16


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Sterile neutrinos: dedicated experiment is needed
Most economic explanation of neutrino oscillations within renormalizable approach: N = 2 Majorana neutrinos Capable of explaining baryon asymmetry of the Universe One more neutrino can serve as (naturally Warm) dark matter MSM direct searches are feasible for MN < 2 GeV (5 GeV) 100-m length detector at SNGS site operated on upgraded SPS beam allows to cover major par t of paramater space 3-km scale detector is needed to fully explore the model
Three Generations of Matter (Fermions) spin ½
Three Generations of Matter (Fermions) spin ½

even with CP = 0

I
mass charge Left name
2.4 MeV

II

III
171.2 GeV

I

II

III
171.2 GeV

Ri g h t

Ri g h t

Right

Right

Right

Left

Left

up

charm

top

gluon 0 0

name

up

charm

top

Ri g h t

Left

Left

Left

u

1.27 GeV



c



t

0 0

g
photon weak force

mass charge

2.4 MeV

u

1.27 GeV



c



t

0 0

g
gluon

Quarks

4.8 MeV

Quarks

Ri g h t

Ri g h t

Right

Right

Right

Left

Left

Left

down

strange

bottom

down

strange

bottom

Ri g h t

-

Left

Left

Left

d
e

104 MeV

-

s

4.2 GeV

-

b


4.8 MeV

-

d

104 MeV

-

s

4.2 GeV

-

b

0 0


photon weak force

Bosons (Forces) spin 1

0 eV

0

Left

Left

electron neutrino
0.511 MeV

Left

Left

Left

muon neutrino
105.7 MeV

tau neutrino
1.777 GeV

Higgs boson

tau muon sterile sterile electron sterile neutrino neutrino neutrino neutrino neutrino neutrino
0.511 MeV

Left



0 eV

0



0 eV



0



91.2 GeV

0

Z

0

>114 GeV 0 0

H

<0.0001 eV ~10 keV

0

e N1 N2 N3
~0.01 eV ~ Ge V ~0.04 eV ~ Ge V

Bosons (Forces) spin 1

91.2 GeV

0

0

0

Z

0

>114 GeV 0 0

H ig g s b o so n

H

Leptons

Leptons

Ri g h t

Ri g h t

Left

Left

Left

electron

muon

tau

weak force

=

Right

Right

Right

Ri g h t

-1

Left

Left

Left

e

-1



-1



80.4 GeV ±

1

W

±

spin 0

-1

electron

e

105.7 MeV

-1

muon



1.777 GeV

-1


tau

80.4 GeV ±

1

weak force

W

±

spin 0

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

15 / 16


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Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

16 / 16


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Backup slides

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

17 / 16


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Heavy sterile neutrinos: M

N

1 keV-5 GeV

MSM

T.Asaka, S.Blanchet, M.Shaposhnikov (2005) 2 2 2 Good fact: small finite quantum corrections mH f 2 MN mH True low-energy scale modification of the SM Good fact: At T > 100 GeV active-sterile neutrino oscillations produce lepton asymmetr y in the early Universe, if MN2,3 MN2 , MN3 E.Akhmedov, V.Rubakov, A.Smirnov (1998)

To make phenomenologically complete: Dark Matter? NOT a seesaw neutrino! m matm,sol N
3 2 52 1/ GF MN N 24 1/ GF MN m 10 11

general statement yr (10 keV/MN )4

either decay or equilibrate and then contribute to hot dark matter production in primordial plasma due to mixing with active neutrinos is ruled out from searches at X-ray telescopes
10-6 10-7 10-8 Phase-space density constraints 10-9 sin2(21) 10-10 10-11 10-12 10
-13

N > DM
1

NRP

X-ray constraints

L6 =25
L6 =70
BBN limit:
max L6 =700

LBBN 6

= 2500


10 50

N

5.5 â 10-22

2 1

M1 1 keV

5

s-1 a narrow line ( E /E v 10

-3

)

10-14 10-15 1

N < DM
1

5 M1 [keV]

at E = MN /2

Possible for 1-50 keV (WDM-CDM range) either with fur ther unbelievable fine-tuning in MNI (MN 10-7 eV) to get L B and use the resonant production or with ANOTHER source of production, e.g. inflaton decays.. then untestable
M.Shaposhnikov, I.Tkachev (2006), F.Bezrukov, D.G. (2009) Dmitry Gorbunov (INR) GeV-scale sterile neutrinos at CERN 26.06.2013, QFTHEP'2013 18 / 16


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Neutrino oscillations: masses and mixing angles
Solar 2 â 2 "subsector" Atmospheric 2 â 2 "subsector"
4.0 4 3.5 3.5 |m2| (10 eV2) 3.0 3 2.5 2.5 2.0 2 1.5 1.5 1.0 1
MINOS best oscillation fit MINOS 90% MINOS 68%

â10

-3

-3

Super-K 90% Super-K L/E 90% K2K 90%

0.6

0.7

0.8 sin2(2)

0.9

1

http://hitoshi.berkeley.edu/neutrino/

arXiv:0806.2237

m1 > 0.008 eV DAYA-BAY, RENO: sin2 213 0.1
Dmitry Gorbunov (INR)

m2 > 0.05 eV
also T2K
(talk by M.Khabibullin) 26.06.2013, QFTHEP'2013 19 / 16

GeV-scale sterile neutrinos at CERN


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Cosmological limits on active neutrino masses
Neutrino contributions: Star t of structure formation Gravity potentials at recombination Late-time structure formation Universe expansion For N = 3 light neutrinos

LRG+BAO+WMAP5+SNe

m < 0.28 eV (95% CL)
0911.5291, see also 1112.4940 Dmitry Gorbunov (INR)

CMB+Hubble measurements m < 0.20 eV (95% CL)
0911.0976, see also 1202.2889

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

20 / 16


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0.27 0.26 0.25

0.005
4He

Baryon density bh2
0.01

0.02

0.03

Yp = 0.2581 ± 0.025 , D /H
p

= (2.87 ± 0.21) â 10

-5

Yp D ___ 0.24 H
0.23 10 - 3
1.0 b+ H+ He
2 2 4

1103.1261

CMB

BBN

D/H p
10 - 4 3 10 - 5

b+ Hlow+ He
2

4

H+ He
CMB 2

4

likelihood

b+Y 0.5

+ H+ He

4

He/H p

10 - 9 5

0.0 0.0

1.0

2.0

3.0

4.0

5.0

Neff

7Li/H p
2 10 - 10 1 2 3 4 5 6 10 7 8 9 10

similar results from other recent studies including structure formation
1001.4440, 1001.5218, 1202.2889

N < 4.2 @ 95%CL
Baryon-to-photon ratio â 10

N < 3.6 from D/H,
26.06.2013, QFTHEP'2013

1205.3785 21 / 16

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN


I N R

Combined analysis for sterile and active neutrinos
WMAP7+LRG+HST
5 4

CMB+SDSS+HST
10

LSND+MiniBooNE

3 N
s

3+2

2

1

2 51
0 0 0.1 0.2 m 0.3 0.4 0.5

m

1

#

0.6 0.5 0.4 m
s

#

Ms = 0
90%, 95%, 99%, 99.73% CL (2 dof)

1+3+1
0.1 0.1

0.3 0.2 0.1 0 0

1 m

10
2 41

1103.4570

0.1

0.2 m

0.3

0.4

0.5

0.5 0.4
s

m

0.3 0.2 0.1 0 0

"3+1" 2 m41 "3+2" 2 m41 2 m51 m = 0 flat CDM

: = 1.76 eV2 , |Ue4 | = 0.151 : = 0.46 eV2 , |Ue4 | = 0.108 = 0.89 eV2 , |Ue5 | = 0.124
1 eV for CMB and

BBN rules out "3+2"
1 2 N
s

3

4

5

For "3+1" to allow MN 1006.5276

LSS we need a new ingredient 26.06.2013, QFTHEP'2013 22 / 16

flat CDM

1102.4774

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN


I N R

LSS: SZ-clusters, Weak lensing of CMB
N amplifies shear power : cancel with quintessence contribution and flattening of spectrum, ns 1 MN reduces power
N
eff

= 3 M < 0.46 eV
eff eff

M = 0 N M < 0.62 eV N
6
6 5

= 3.8 ± 0.4 = 3.9 ± 0.4
1212.3608

Neff nnu

5
nnu

4 3 0.1 0.12 0.14 2 ! !DM h 2 h
DM

4 3

0.16

0.94

0.96

0.98 ns

n

1

1.02

s

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

23 / 16


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MSM parameter space with resonant DM

NuTeV CHARM 10
6 6

NuTeV
PS191

10

CHARM
PS191

BAU
2

U

BAU
DM 10
10 10

U

10

8

2

BAU constrained MSM

BAU
10
8

BAU

BBN
BAU

constrained MSM

BBN

DM 10

Seesaw

Seesaw

10

12

10 0.2 0.5 1.0 M GeV 2.0 5.0 10.0

12

0.2

0.5

1.0 M GeV

2.0

5.0

10.0

L.Canetti, M.Drewes, M.Shaposhnikov 1204.3902

Dmitry Gorbunov (INR)

GeV-scale sterile neutrinos at CERN

26.06.2013, QFTHEP'2013

24 / 16


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Lightest sterile neutrino N1 as Dark Matter
10-6

10-10 10-11 10-12 10-13 10-14 10-15

Phase-space density constraints

Non-resonant production (active-sterile mixing) is ruled out
sin2(21)

10-7 10-8 10-9

N > DM
1

NRP

X-ray constraints

L6 =25
L6 =70
BBN limit:
max L6 =700

Resonant production (lepton asymmetr y) requires M2,3 10-16 GeV
arXiv:0804.4542, 0901.0011, 1006.4008

LBBN 6

= 2500

N < DM
1

1

5 M1 [keV]

10

50

Dark Matter production from inflaton decays in plasma at T m

Not seesaw neutrino!

I

M.Shaposhnikov, I.Tkachev (2006)

¯ ¯ MNI NIc NI fI X NI N m 300 MeV

Can be "naturally" Warm (250 MeV < m < 1.8 GeV) M
Dmitry Gorbunov (INR)

F.Bezrukov, D.G. (2009)

1

15 â

keV
26.06.2013, QFTHEP'2013 25 / 16

GeV-scale sterile neutrinos at CERN