Neutrino mass and the LHC

ICTP, Trieste

Miha Nemevšek

Balkan Workshop 2011, Donji Milanovac

with Maiezza, Melfo, Nesti, Senjanović, Tello, Vissani and Zhang

LHC a neutrino machine?

Neutrino mass is an experimentallyestablished fact for BSM physics.

Might as well be @ TeV (hierarchy)

A phenomenological hint may already be here

Neutrino mass and BSM

!m

2

S,A & !A,S,13

Facts Questions

Mass scale & hierarchy

CP phases

Dirac or MajoranaAt least two massive light

neutrinos

The theory of neutrino mass?

LHC may play a crucial role

Low-high energy interplay becomes important

Origin of

Standard Model only,

m!

!L m! = 0

Effective theory

High scale

Typical in GUTs

Indirect, LHC of little use

TeV

Theory: GUT remnant

Phenomenological

Neutrino mass and the LHC

OW = y!h!h

!! m! =

y2v2

!

UV completions of OW

I! S

h

!

h II! !

!

h h III!

T 0

h

!

h

Fermionic singlet Bosonic triplet Fermionic triplet

Renormalizable theory = seesaw scenarios

Type I+III

Triplet predicted at TeV by a minimal SU(5) with

Neutrino mass matrix through decays

Oscillations-collider connection

24F

Bajc, Senjanović ’06Bajc, MN, Senjanović ’07

UV completions of OW

I! S

h

!

h II! !

!

h h III!

T 0

h

!

h

Fermionic singlet Bosonic triplet Fermionic triplet

Type I+IIPredicted by a minimal LR symmetric theory

Singlet is gauged, type I required by anomalies

Triplet breaks the LR symmetry - type II

May need to be light !!

Left-Right symmetry

!

!L

eL

"

, WL !

!

!R

eR

"

, WR

Parity restoration at high scales

Spontaneously broken

Origin of the seesaw mechanismMinkowski ’77Senjanović ’79

Senjanović, Mohapatra ’80

Pati, Salam ’74Mohapatra, Pati ’75

Mohapatra, Senjanović ’75

Minimal LR Model

SU(2)L ! SU(2)R ! U(1)B!L

LR symmetric Higgs sector, parity invariant L

!(2, 2, 0), "L(3, 1, 2), "R(1, 3, 2)

First stage @ TeV

Breaks and Lepton numberSU(2)R

Second stage @ 100 GeV

MWR= g vR, mN = y vR

!!R" =

!

0 0

vR 0

"

!!L" # vL = 0

!!" =

!

v1 0

0 v2ei!

"

vL = ! v2/vR

MW ! v "

!

v21

+ v22, mD ! v

Mass spectra

LY = !L(Y! ! + Y! !)!R + !TL Y"L

"L!L + !TR Y"R

"R!R + h.c.

MD = v1 Y! + v2 e!i! Y!,

M" = v2 ei! Y! + v1 Y!

M!R= vR Y!R

M!L= vL Y!L

! MTD M

!1!R

MD

C : Y! = Y!T , Y"L,R

= Y"R,L

!

Dirac terms Majorana terms

Mass eigenstate basis

C : U!L = U!

!R

M! = U!L m! U†!R

, M"L= U!

"L m" U†"L

, M"R= U!

"R mN U†"R

Flavor fixed in type II:

Remember; two angles, one limit, no phases

VR!

= VL

The Interactions

Lcc =g!

2

!

!LVL† /W "L + !RVR

† /WR "R

"

New Scalar:

New Gauge:

L!++ = eTR Y !

++R

eR

Y =

g

MWR

VR!mNVR

†

Flavor fixed in type II:

Remember; two angles, one limit, no phases

VR!

= VL

The Interactions

Lcc =g!

2

!

!LVL† /W "L + !RVR

† /WR "R

"

New Scalar:

New Gauge:

L!++ = eTR Y !

++R

eR

Y =

g

MWR

VR!mNVR

†

LHC could eventually measure these

Example only!

Bounds on the LR scale

Theoretical bounds since ’81

A recent detailed study, including CP violation

Beall et al. ’81...Zhang et al. ’07

Direct searches

Dijets

Light neutrino

LHC is here!

Maiezza, Nesti, MN, Senjanović ’10

C : MWR> 2.5 TeV P : MWR

> 3.2 ! 4.2 TeV

CMS 1107.4771

CMS PAS EXO-11-024MWR> 2.27 TeV

MWR> 1.51 TeV

L ! 2.5 fb!1

Left-Right @ LHC

Most interesting channel: l l j j

LNV at colliders

p

p

WR

!i

N!

!j

WR

j

j

VRi!

VRj!

Keung, Senjanović ’83

Gauge production: s-channel,

W nearly on-shell

Clean, no missing energy

Reconstructs W and N masses

Information on the flavor

Limits from the LHC

1.64`

23

4

800 1000 1200 1400 1600 18000

200

400

600

800

1000

MWR !GeV"

MN

!!GeV

"

D0:dijets

L!33.2pb"1

1.64`

2

34

800 1000 1200 1400 1600 18000

200

400

600

800

1000

MWR !GeV"MN!!GeV

"

D0:dijets

L"34pb#1

MN, Nesti, Senjanović, Zhang ’11

High N inaccessible due to jets, low N due to isolation

This year:

Electron and muon channel essentially the same

L = 0.1(1) fb!1 : MWR> 1.6(2.2)TeV

March

Limits from the LHC

1.64`

23

4

800 1000 1200 1400 1600 18000

200

400

600

800

1000

MWR !GeV"

MN

!!GeV

"

D0:dijets

L!33.2pb"1

1.64`

2

34

800 1000 1200 1400 1600 18000

200

400

600

800

1000

MWR !GeV"MN!!GeV

"

D0:dijets

L"34pb#1

MN, Nesti, Senjanović, Zhang ’11

High N inaccessible due to jets, low N due to isolation

This year:

Electron and muon channel essentially the same

L = 0.1(1) fb!1 : MWR> 1.6(2.2)TeV

March

[GeV]RWM

800 1000 1200 1400 1600

[G

eV

]e

NM

0

200

400

600

800

1000

1200Observed

Expected

RW > MeNM

Exclu

de

d b

y T

eva

tro

n

CMS Preliminary

at 7 TeV-1240 pb

[GeV]RWM

800 1000 1200 1400 1600

[G

eV

]µ

NM

0

200

400

600

800

1000

1200Observed

Expected

RW > MµNM

Exclu

de

d b

y T

eva

tro

n

CMS Preliminary

at 7 TeV-1240 pb

July

CMS PAS EXO-11-002

Low/high energy interplay

Majorana mass term dominanceM!R

= vR Y M!L= vL Y

!

Implications for masses and mixings

mN ! m! U!R = U!

!L ! VR = V!

L

mN2

2 ! mN1

2

mN3

2 ! mN1

2=

m!2

2 ! m!1

2

m!3

2 ! m!1

2" ±0.03

mcosm =

!

!m2A

"

imNi

!

|mN3

2 ! m2N2

|,

Hierarchy probe @ LHC

Cosmo-oscillations-LHC link

lightest neutrino mass in eV

normal

inverted

|mee !

|in

eV

10!4 0.001 0.01 0.1 110!4

10!3

0.01

0.1

1.0

10!4 0.001 0.01 0.1 110!4

0.001

0.01

0.1

1

1

and cosmology0!2"

0!2"

Gerda, Cuore, Majorana,...

Majorana mass implies

Claim of observation

Vissani ’99

Review by Rodejohann ’11

|mee

!| ! 0.4 eV

Klapdor-Kleingrothaus ’06, ’09

and cosmology0!2"

lightest neutrino mass in eV

normal

inverted

|mee !

|in

eV

10!4 0.001 0.01 0.1 110!4

10!3

0.01

0.1

1.0

10!4 0.001 0.01 0.1 110!4

0.001

0.01

0.1

1

1

Cosmological bounds!

m! < 0.17 eV

!m! < 0.44 eV

Seljak et al. ’06

WMAP alone

Hannestad et al. ’10

If confirmed, a hint for NPVissani ’02

WR

New Diagrams for

!L !R

n

n

WR

p

N!

e

WR

e

p

VRe!

VRe!

n

n

W

p

W

!L

p

e

e

vL

(YL)ee

n

n

WR

p

WR

!R

p

e

e

vR

(YR)ee

0!2"

Large? Tiny Subdominant?

In agreement with cosmology?

! 1/mN ! m! ! mN

Mohapatra, Senjanović ’81

: the new contribution0!2"

c

AZX

AZ`1X A

Z`2X

WL;R

e

!; N

e

WL;R

AZX

AZ`1X A

Z`2X

WL;R WL;R

´L;R

e

eLR mixings small

sin ! < MW /MWR< 10

!3

mD ! 0

HNP = G2F VR

2ej

!

1

mN j+

2 mN j

m2!

"

M4W

M4WR

JRµJµR eRe

cR

Type II: VR!

= VL suppressed:!L m!/m! ! 1

LFV: mN/m!R< 1

The gauge contribution is dominant

LHC accessible regime

: the total contribution0!2"

Interference small

Reversed role of hierarchies

No tension with cosmology

A light

No cancellations

lightest mN in GeV

lightest neutrino mass in eV

normalinverted

MWR = 3.5 TeV

largest mN = 0.5 TeV

|mee !

+N|i

neV

1 10 100 400 500

10!4 0.001 0.01 0.1 110!3

0.01

0.1

1.0

10!4 0.001 0.01 0.1 10.001

0.0050.01

0.050.1

0.51.

1

|m!+Nee|2 !

|m!ee|2 + |mN

ee|2

mN < MWR

|M!+Nee|2 = |m!1

cos2 !12 + m!2

ei"sin

2 !12|2

+!

!

!

!

p2 M4W

M4WR

"

1

mN1

cos2 !12 +

1

mN2

ei"sin

2 !12

#!

!

!

!

2

LHC and

Suppose NP is a must for ;0!2" !13 ! 0 ! = 2("2 ! "1)

0!2"

|M!+Nee|2 = |m!1

cos2 !12 + m!2

ei"sin

2 !12|2

+!

!

!

!

p2 M4W

M4WR

"

1

mN1

cos2 !12 +

1

mN2

ei"sin

2 !12

#!

!

!

!

2

LHC and

Suppose NP is a must for ;

0.0001 0.001 0.01 0.1 15

10

20

50

100

200

500

1000

lightest neutrino mass in eV

Normal HierarchyMWR = 3.5TeV, ! = 0

mN1in

GeV

10!4 0.001 0.01 0.1 15

10

20

50

100

200

500

1000

|Mee"+N |

1.0

0.60.4

0.2

0.1

0.05

1

0.0001 0.001 0.01 0.1 15

10

20

50

100

200

500

1000

lightest neutrino mass in eV

Normal HierarchyMWR = 3.5TeV, ! = "

mN1in

GeV

10!4 0.001 0.01 0.1 15

10

20

50

100

200

500

1000

|Mee#+N |

1.0

0.60.4

0.2

0.1

0.05

1

0!2" !13 ! 0 ! = 2("2 ! "1)

jj : mN ! 50 GeV

j! : mN ! 20 GeV

/v : mN ! 20 GeV

/E : mN ! 3 ! 7 GeVLHC:

0!2"

|M!+Nee|2 = |m!1

cos2 !12 + m!2

ei"sin

2 !12|2

+!

!

!

!

p2 M4W

M4WR

"

1

mN1

cos2 !12 +

1

mN2

ei"sin

2 !12

#!

!

!

!

2

LHC and

Suppose NP is a must for ;

0.0001 0.001 0.01 0.1 15

10

20

50

100

200

500

1000

lightest neutrino mass in eV

Normal HierarchyMWR = 3.5TeV, ! = 0

mN1in

GeV

10!4 0.001 0.01 0.1 15

10

20

50

100

200

500

1000

|Mee"+N |

1.0

0.60.4

0.2

0.1

0.05

1

0.0001 0.001 0.01 0.1 15

10

20

50

100

200

500

1000

lightest neutrino mass in eV

Normal HierarchyMWR = 3.5TeV, ! = "

mN1in

GeV

10!4 0.001 0.01 0.1 15

10

20

50

100

200

500

1000

|Mee#+N |

1.0

0.60.4

0.2

0.1

0.05

1

0.0001 0.001 0.01 0.1 15

10

20

50

100

200

500

1000

lightest neutrino mass in eV

Inverted HierarchyMWR = 3.5TeV, ! = 0

mN1in

GeV

10!4 0.001 0.01 0.1 15

10

20

50

100

200

500

1000

|Mee"+N |

1.0

0.60.4

0.2

0.1

0.05

1

0.0001 0.001 0.01 0.1 15

10

20

50

100

200

500

1000

lightest neutrino mass in eV

Inverted HierarchyMWR = 3.5TeV, ! = "

mN1in

GeV

10!4 0.001 0.01 0.1 15

10

20

50

100

200

500

1000

|Mee#+N |

0.60.4

0.2

0.10.05

1

0!2" !13 ! 0 ! = 2("2 ! "1)

jj : mN ! 50 GeV

j! : mN ! 20 GeV

/v : mN ! 20 GeV

/E : mN ! 3 ! 7 GeVLHC:

0!2"

Lepton Flavor Violation

LFV rates computable: type II (or LHC)

tree

loop

log

µ

e e

!++L,R

e

Y!!

ee

Y!µe

µ

!++

!ci

e

"

!++

Y!µi Y!!

ie

N

µL eL

!L("L)

!++L

(!+L

)

N

!++L

(!+L

)

#, ZL, ZR

Y! Y!!

! ! 3!

! ! !!"

µ N ! e N

Cirigliano et al ’04

VL mN/m! VLT

VL mN/m! VL†

VL mN/m! VL†

Raidal, Santamaria ’97

Combined LFV constraints

lightest neutrino mass in eV

absolute bound from LFV

always allowed by LFV

Inverted HierarchyMWR = 3.5TeV

m/m

N!

10!4 0.001 0.01 0.1 10.01

0.05

0.1

0.5

1.0

5.0

10!4 0.001 0.01 0.1 10.01

0.05

0.1

0.5

1.

5.

1

lightest neutrino mass in eV

absolute bound from LFV

always allowed by LFV

Normal HierarchyMWR = 3.5TeV

m/m

N!

10!4 0.001 0.01 0.1 10.01

0.05

0.1

0.5

1.0

5.0

10!4 0.001 0.01 0.1 10.01

0.05

0.1

0.5

1.

5.

1

Muonic and tau channels

Varying PMNS constrains mN/m! < 1

Tello, MN, Senjanović, Vissani ’10

98.5 97.3 100118.4

136146 141 150

114

144156

313

2001 2003 2003 2004 2004 2005 2006 2008 2008 2011 2011 20110

50

100

150

200

250

300

3502001 2003 2003 2004 2004 2005 2006 2008 2008 2011 2011 2011

m!""

Opal Delphi## L3 CDF

$$CDFe&$

CDF%!0

H1e$

D0$$

CDFIIe#

D0$#

CMSApril

CMSJuly

Triplet searches

LHC

! =

!

!+/!

2 !++

!0"!+/

!

2

"

Gauge Production

Associated via

Pair-wise through

W±!±±

!!

W±!±

!0

Z!0

!0

!!, Z!+

!"

!!, Z!++

!""

Z, !!

W

GeV

! =

!

!+/!

2 !++

!0"!+/

!

2

"

Gauge Production

Associated via

Pair-wise through

W±!±±

!!

W±!±

!0

Z!0

!0

!!, Z!+

!"

!!, Z!++

!""

Z, !!

W

100 120 140 160 180 200

1.00

0.50

2.00

0.20

0.10

0.05

0.02

M! !TeV"

"!pb"

LHC @ 7 TeV

solid=LO

dashed=NLO

K-factor =1.3

red = assoc.

blue=pair.GeV

Decay Phase Diagram

Decays

a) Leptonic

b) Gauge boson

c) Cascade

D0: pair-production only, CMS degenerate mass

! ! !!

! ! V V

! ! !!V

Tiny

Large

Mass split

v!

v!

!!!!!V ! "m5/m4W

a) b) c)!!!V V !

m3!v!

2

v4

!!!!! !m!U"m"U †

v!

Decay Phase Diagram

Decays

a) Leptonic

b) Gauge boson

c) Cascade

D0: pair-production only, CMS degenerate mass

! ! !!

! ! V V

! ! !!V

Tiny

Large

Mass split

v!

v!

!!!!!V ! "m5/m4W

a) b) c)!!!V V !

m3!v!

2

v4

!!!!! !m!U"m"U †

v!

Cascade Decay

Leptonic DecayGauge

Boson Decay

10!10 10!8 10!6 10!4 0.01 1

0.51.0

5.010.0

50.0100.0

v" !GeV"

"M!GeV

"

c

Mass splits

c

The general potential

Splits components by ; there is a sum rule

V = ! m2H H†H + m2

!Tr!†! + (µHT i!2!!H + h.c.)+

"1(H†H)2 + "2(Tr!†!)2 + "3Tr(!†!)2+

# H†H Tr!†! + $ H†!!†H

v2

m2

!+ ! m2

!++ " m2

!0 ! m2

!+ " ! v2/4

mS " mA = m!0

Only two mass scales govern the spectrum up to O

!

v2

v!2

"

Electroweak Precision Tests

EWPT calculated for the first time

Oblique parameters suffice (Yukawa small by LFV)

100 200 300 400 500 600

!40

!20

0

20

40

60

80

100

mh!GeV"

#m "# !m"##$!GeV

"

m"##$200 GeV

68%95%

99%

T positive definite, controlled by mass splits

Heavy Higgs=negative T

T parameter

Bottom-line

O(10 GeV) splits allowed

Cascade region opens up...

Melfo, MN, Nesti, Senjanović, Zhang ’11

c

Type II Roadmap

Direct searchLHC 980 pb!1!v"#10!6GeV"

Sum Rule

Sum Rule &Z width

LEP

EWPTmh#300GeV

0 100 200 300 400 500 600 700

!100

!50

0

50

100

m"$$ #GeV$

m"$!m"$$#GeV

$ Direct searchLHC 980 pb!1!v"#10!6GeV"

Sum Rule

Sum Rule &Z width

LEP EWPTmh#130GeV

!

0 100 200 300 400 500 600 700

!100

!50

0

50

100

m"$$ #GeV$

m"$!m"$$#GeV

$ ! < 3

CMS data

Melfo, MN, Nesti, Senjanović, Zhang ’11

CMS-PAS-HIG-11-007

Light Higgs

cmh = 130 GeV

c

Type II Roadmap

Direct searchLHC 980 pb!1!v"#10!6GeV"

Sum Rule

Sum Rule &Z width

LEP

EWPTmh#300GeV

0 100 200 300 400 500 600 700

!100

!50

0

50

100

m"$$ #GeV$

m"$!m"$$#GeV

$ ! < 3

CMS data

Melfo, MN, Nesti, Senjanović, Zhang ’11

CMS-PAS-HIG-11-007

Heavy Higgs

cmh = 300 GeV

Conclusions

signal may require new physics at TeV

Left-Right symmetry @ LHC a natural example

no tension with cosmology, precision data or LFV

links oscillations, cosmology and the LHC

Exclusions with fairly low luminosity and 7 TeV

LHC may observe LNV and in turn connect it to low

energy rates, both LNV and LFV

0!2"

Thank you.

Higgs decay

Heavy Higgs decay: a way to probe !

500200 3001500.0

0.5

1.0

1.5

Mh !GeV"

!

10"

100"

Br(h ! WW )mh > 2m!

!h!!++!!! ! !2

!h!!+!! ! (! + "/2)2

Higgs Br’s change

Easy to search if

Hidden if

!++

!0

Akeroyd, Moretti ’11

Melfo, MN, Nesti, Senjanović, Zhang ’11

1.64`

23

4

1000 1500 2000 2500 30001

5

10

50

100

500

1000

MWR !GeV"

MN

!!GeV

"

CMS ! ! Missing Energy

! ! Displaced Vertex

! ! jet#EM activity"N#1 mm

"N#5 m

0$2%$HM%

D0:dijets

L&33.2pb'1

A global pictureMN, Nesti, Senjanović, Zhang ’11

Non-minimal case

1200 1300 1400 1500 1600 1700 1800

0.6

0.8

1.0

1.2

1.4

MWR !GeV"

gR#g L

Minimal case: gL = gR C : VLCKM

= VRCKM!

Maiezza, Nesti, MN, Senjanović ’10

mN = 500 GeV

95% CL

And the ?

Less important, loop suppressed

no log enhancement

flavor structure always

WR

Still, future useful

J-PARC and Fermilab

could probe the mediator

even CP phases if LR

µ N ! e N

Cirigliano, Kitano, Okada, Tuzon ’09

Bajc, MN, Senjanović ’09

VL mN/MWRVL

†

mN < MWR

Role of

Flavor structure in muon-electron transitions

!13

A(µ ! e) "!m2

N13

m2!++

!

!m2S

2!m2A

sin 2!12 cos !23 + ei! sin !13 sin !23

"

A(µ ! 3e) "!

#mN1+ expi! mN2

"

sin 2!12 cos !23!

mN1cos2 !12 + expi! mN2

sin2 !12

"

/m2

!++

conversion and depend a lotµ ! e µ ! e!

insensitive to µ ! 3e !13

Role of

Flavor structure in muon-electron transitions

!13

A(µ ! e) "!m2

N13

m2!++

!

!m2S

2!m2A

sin 2!12 cos !23 + ei! sin !13 sin !23

"

A(µ ! 3e) "!

#mN1+ expi! mN2

"

sin 2!12 cos !23!

mN1cos2 !12 + expi! mN2

sin2 !12

"

/m2

!++

conversion and depend a lotµ ! e µ ! e!

insensitive to µ ! 3e !13

0 !2 ! 3 !

22 !

0.200

0.100

0.050

0.020

0.010

0.005

0.002

0.001

"

#mS2

2#mA2!sin2$

12cos$23%ei"sin$ 13sin$ 23" Impact of non&zero $13

T2Ksin22$13'0.11

Minossin22$13'0.04

sin22$13'8x10&4

$13'0